three page essay

follow the request, three pages 

79

3

CHAPTER 1

4

The Bioecological Model of
Human Development

URI E BRONFENBRENNER and PAM ELA A. MORRIS

OVERVIEW 79

5

DEFINING PROPERTIES OF TH E

BIOECOLOGICAL MODEL 79

6

Proposition I 79

7

Proposition II 79

8

FROM TH EORY TO RESEARCH DESIGN:

OPERATIONALIZING TH E
BIOECOLOGICAL MODEL 799

Developmental Science in the Discovery Mode 801
Dif ferent Paths to Dif ferent Outcomes: Dysfunction

versus Competence 803
The Role of Experiments in the Bioecological Model 808
HOW DO PERSON CHARACTERISTICS INFLUENCE

LATER DEVELOPMENT? 81

0

Force Characteristics as Shapers of Development 8

10

Resource Characteristics of the Person as Shaper

s

of Development 81

2

Demand Characteristics of the Person as

Developmental Inf luences 8

12

TH E ROLE OF FOCUS OF ATTENTION IN

PROXIMAL PROCESSES 813

PROXIMAL PROCESSES IN SOLO ACTI VITIES
WITH OBJECTS AND SYMBOLS 814

TH E MICROSYSTEM MAGNIFIED: ACTI VITIES,
RELATIONSH IPS, AND ROLES 814

Ef fects of the Physical Environment on
Psychological Development 814

The Mother-Infant Dyad as a Context of Development 815
BEYOND TH E MICROSYSTEM 817
The Expanding Ecological Universe 818
Nature-Nurture Reconceptualized:

A Bioecological Interpretation 819
TIME IN TH E BIOECOLOGICAL MODEL:

MICRO-, MESO-, AND
MACROCHRONOLOGICAL SYSTEMS 8

20

FROM RESEARCH TO REALITY 822
TH E BIOECOLOGICAL MODEL: A

DEVELOPMENTAL ASSESSMENT 824
REFERENCES 825

The bioecological model, together with its correspon-
ding research designs, is an evolving theoretical system
for the scientific study of human development over tim

e

(Bronfenbrenner, 2005). In the bioecological model, de-
velopment is defined as the phenomenon of continuity
and change in the biopsychological characteristics of
human beings, both as individuals and as groups. The
phenomenon extends over the life course, across succes-

We are especially grateful for the thoughtful criticisms of
earlier drafts of the manuscript generously provided by the
following colleagues: Jay Belsky, Rick Canf ield, Nancy Dar-
ling, Glen H. Elder Jr., Steven F. Hamilton, Melvin L. Kohn,
Kurt Lüscher, Phyllis Moen, Donna Dempster-McLain, Lau-
rence Steinberg, and Sheldon H. White. We owe particular
thanks to Professor Susan Crockenberg and her students at
the University of Vermont who, in the course of a graduate

sive generations, and through historical time, both past
and future. The term future raises a question: How is it
possible to scientifically investigate phenomena that
have not yet taken place? This question is hardly new;
indeed, it pervades every field of scientific endeavor.
However, we are the only species that, over historical
time, has developed the capacity to engage successfully
in scientific inquiry, and thereby, in many respects, has

seminar, carefully reviewed a draft of this chapter, and made
many constructive suggestions. We have done our best to
meet the high standards that they commendably set. We wish
to express gratitude to Richard M. Lerner and William
Damon, the editors of the 1998 Volume and of that series as a
whole, for their wise advice, encouragement , and patience.
Finally, a special thanks goes to our most severe and most
constructive critic, Liese Bronfenbrenner.

794 The Bioecological Model of Human Development

been able to change the nature of the world in which we
live. As a result, within certain limits, we humans have
altered the nature and course of our own development as
a species (Bronfenbrenner & Evans 2000; Bronfenbren-
ner & Morris 1998).

To place bioecological theory of human development
into a larger context, it is important to recognize that
many of the general perspectives advanced and elabo-
rated in this theory are also parts of other related lines
of theoretical and empirical inquiry into human devel-
opment. Examples include life-span psychology (Baltes,
Lindenberger, & Staudinger, Chapter 11, this Handbook,
this volume), cultural psychology (Cole, 1995; Shweder
et al., Chapter 13, this Handbook, this volume), Magnus-
son’s developmental theory of contextual-interactive
holism (Magnusson & Stattin, Chapter 8, this Hand-
book, this volume), and, especially, the work of Robert
Cairns (Chapter 3, this Handbook, this volume), who
through communications and publications extending
over 3 decades, has played a major role in the evolution
of the four defining properties of the bioecological
model: (1) Process, (2) Person, (3) Context, and (4)
Time. Cairns is best known as the founder and principal
protagonist of developmental science, and there are sev-
eral excellent examples of his books and articles that
have been most relevant to the evolution of the bioeco-
logical model (Bergman, Cairns, Nilsson, & Nysted,
2000; Cairns, 1970; Cairns & Cairns, 1994). The spe-
cific profile of the bioecological model of human devel-
opment is its interdisciplinary and integrative focus on
the age periods of childhood and adolescence and its ex-
plicit interest in applications to policies and programs
pertinent to enhancing youth and family development.

In this chapter, we undertake to present the ecologi-
cal model of human development that has been intro-
duced over the course of the prior two editions of this
Handbook (Bronfenbrenner & Crouter, 1983; Bronfen-
brenner & Morris, 1998). The main focus of the 1983
chapter was on the empirical and theoretical roots of a
model already in use, which centered on the role of the
environment in shaping development. In contrast, this
chapter is oriented toward the future. The present model
introduces major theoretical innovations from the 1983
chapter in both form and content. The present formula-
tion makes no claim as a paradigm shift (if there be such
a phenomenon); rather, it continues a marked shift in the
center of gravity of the model, in which features of ear-
lier versions are first called into question but then re-

combined, along with new elements, into a more com-
plex and more dynamic structure.

The transition in the form and content of the model
actually took place over an extended period of time, an
expression that will become all too familiar to the reader
(Bronfenbrenner, 2005). The transition from a focus on
the environment to a focus on processes was first intro-
duced in the context of Bronfenbrenner’s unpublished
lectures, colloquium presentations, and contributions
to symposia. Not until 1986, did reference to an emer-
gent new model first appear in print (Bronfenbrenner,
1986b). The following extended excerpt conveys both its
spirit and intended substance. Because both of these at-
tributes are relevant to the gradual evolution of the
model to its present form, we quote from the 1986 state-
ment at some length:

It is now more than a decade ago that , being somewhat
younger, I presumed to challenge the then-prevailing con-
ventions of our f ield by describing the developmental re-
search of the day as “ the study of the strange behavior of
children in strange situations for the briefest possible pe-
riod of time” ( Bronfenbrenner, 1974). Instead, I argued (as
if it were simply a matter of choice), we should be studying
development in its ecological context; that is, in the actual
environments in which human beings lived their lives. I
then proceeded to outline, in a series of publications, a con-
ceptual framework for analyzing development in context ,
and to offer concrete examples of how various elements of
the schema might be applied both to past studies and to
studies yet-to-come. I also emphasized the scientif ic and
practical benef its of a closer linkage, in both directions, be-
tween developmental research and public policy ( Bronfen-
brenner, 1974, 1975, 1977a , 1977b, 1979a , 1979b, 1981).
Now, a dozen years later, one might think that I have good
reason to rest content. Studies of children and adults in
real-life settings, with real-life implications, are now com-
monplace in the research literature on human development ,
both in the United States and, as this volume testif ies, in
Europe as well. This scientif ic development is taking place,
I believe, not so much because of my writings, but rather
because the notions I have been promulgating are ideas
whose time has come. . . .

Clearly, if one regards such scientif ic developments as
desirable, there are grounds for satisfaction. Yet , along
with feelings of gratif ication, I must confess to some dis-
content. My disquiet derives from two complementary
concerns. The f irst pertains to one of the main roads that
contemporary research has taken; the second, to some
more promising pathways that are being neglected.

Overview 795

Alas, I may have to accept some responsibility for what
I regard as the wayward course. It is an instance of what
might be called “ the failure of success.” For some years, I
harangued my colleagues for avoiding the study of devel-
opment in real-life settings. No longer able to complain on
that score, I have found a new bête noir. In place of too
much research on development “out of context ,” we now
have a surfeit of studies on “context without development.”

One cannot presume to make so brass an allegation
without being prepared to document one’s case. I am pre-
pared. ( Bronfenbrenner 1986a , pp. 286 –288)

What followed was an early version of the newly evolv-
ing theoretical framework, but the purpose of the pres-
ent chapter is better served by presenting the model in
its current, albeit still-evolving, form now called the
bioecological model. The term evolving highlights that
the model, along with its corresponding research de-
signs, has undergone a process of development during its
life course (Bronfenbrenner, 2005). The bioecological
model addresses two closely related but fundamentally
different developmental processes, each taking place
over time. The first process defines the phenomenon
under investigation—continuity and change in the
biopsychological characteristics of human beings. The
second focuses on the development of the scientific
tools—theoretical models and corresponding research
designs required for assessing continuity and change.

These two tasks cannot be carried out independently,
for they are the joint product of emerging and converg-
ing ideas, based on both theoretical and empirical
grounds—a process called developmental science in the
discovery mode (Bronfenbrenner & Evans 2000,
pp. 999–1000). In the more familiar verification mode,
the aim is to replicate previous findings in other settings
to make sure that the findings still apply. By contrast, in
the discovery mode, the aim is to fulfill two broader but
interrelated objectives:

1. Devising new alternative hypotheses and correspon-
ding research designs that not only question existing
results but also yield new, more differentiated, more
precise, replicable research findings and, thereby,
produce more valid scientific knowledge.

2. Providing scientific bases for the design of effective
social policies and programs that counteract newly
emerging developmentally disruptive inf luences.
This has been an explicit objective of the bioecologi-
cal model from its earliest beginnings. To orient the

reader to the present formulation of the biological
model, a preview follows.

OVERVIEW

We begin with an exposition of the defining properties
of the model, which involves four principal components
and the dynamic, interactive relationships among them.
The first of these, which constitutes the core of the
model, is Process. More specifically, this construct en-
compasses particular forms of interaction between or-
ganism and environment, called proximal processes, that
operate over time and are posited as the primary mech-
anisms producing human development. However, the
power of such processes to inf luence development is
presumed, and shown, to vary substantially as a func-
tion of the characteristics of the developing Person, of
the immediate and more remote environmental Contexts,
and the Time periods, in which the proximal processes
take place.

The sections that follow examine in greater detail each
of the three remaining defining properties of the model,
beginning with the biopsychological characteristics of
the Person. This domain was given sequential priority to
fill a recognized gap in earlier prototypes of the ecologi-
cal model. Thus, at midstage in the development of the
present model, Bronfenbrenner criticized its theoretical
predecessors and acknowledged his share of responsibil-
ity for failing to deliver on an empirical promise:

Existing developmental studies subscribing to an ecologi-
cal model have provided far more knowledge about the na-
ture of developmentally relevant environments, near
and far, than about the characteristics of developing indi-
viduals, then and now. . . . The criticism I just made also
applies to my own writings. . . . Nowhere in the 1979
monograph, nor elsewhere until today, does one f ind a
parallel set of structures for conceptualizing the charac-
teristics of the developing person. ( Bronfenbrenner,
1989a , p. 188)

Three types of Person characteristics are distin-
guished as most inf luential in shaping the course of
future development through their capacity to affect
the direction and power of proximal processes through
the life course. First, dispositions can set proximal
processes in motion in a particular developmental
domain and continue to sustain their operation. Next,

796 The Bioecological Model of Human Development

bioecological resources of ability, experience, knowl-
edge, and skill are required for the effective function-
ing of proximal processes at a given stage of
development. Finally, demand characteristics invite or
discourage reactions from the social environment
that can foster or disrupt the operation of proximal
processes. The differentiation of these three forms
leads to their combination in patterns of Person struc-
ture that can further account for differences in the di-
rection and power of resultant proximal processes and
their developmental effects.

These new formulations of qualities of the person
that shape his or her future development have had the
unanticipated effect of further differentiating, expand-
ing, and integrating the original 1979 conceptualiza-
tion of the environment in terms of nested systems
ranging from micro to macro (Bronfenbrenner, 1979b).
For example, the three types of Person characteristics
previously outlined are also incorporated into the defi-
nition of the microsystem as characteristics of parents,
relatives, close friends, teachers, mentors, coworkers,
spouses, or others who participate in the life of the de-
veloping person on a fairly regular basis over extended
periods of time.

The bioecological model also introduces an even
more consequential domain into the structure of the mi-
crosystem that emphasizes the distinctive contribution
to development of proximal processes involving inter-
action not with people but with objects and symbols.
Even more broadly, concepts and criteria are introduced
that differentiate between those features of the environ-
ment that foster versus interfere with the development of
proximal processes. Particularly significant in the latter
sphere is the growing hecticness, instability, and chaos
in the principal settings in which human competence
and character are shaped—in the family, child-care
arrangements, schools, peer groups, and neighborhoods.

The latter theme speaks to the fourth and final defin-
ing property of the bioecological model and the one that
moves it farthest beyond its predecessor—the dimension
of Time. The 1979 Volume scarcely mentions the term,
whereas in the current formulation, it has a prominent
place at three successive levels: (1) micro-, (2) meso-,
and (3) macro-. Microtime refers to continuity versus
discontinuity in ongoing episodes of proximal process.
Mesotime is the periodicity of theses episodes across
broader time intervals, such as days and weeks. Finally,
Macrotime focuses on the changing expectations and
events in the larger society, both within and across gen-

erations, as they affect and are affected by, processes
and outcomes of human development over the life
course. The treatment of this last topic draws on Elder
and Shanahan, Chapter 12, this Handbook, this volume.
Our primary emphasis, however, is on the role of devel-
opmental processes and outcomes in producing large-
scale changes over time in the state and structure of the
broader society over time, and the implications of those
changes for the society’s future.

Before turning to the task at hand, it is important to
make explicit three overarching orientations that define
the content and the structure of the chapter as a whole.
First, we use the term development to refer to stability
and change in the biopsychological characteristics of
human beings over the life course and across genera-
tions. There are no restrictive assumptions of change
for the better or of continuity in the characteristics of
the same person over time. Rather, these are issues to
be investigated.

Second, from the perspective of the bioecological
model, the forces producing stability and change in the
characteristics of human beings across successive gen-
erations are no less important than stability and change
in the characteristics of the same person over his or
her lifetime.

The third orientation is perhaps the most essential,
and the most difficult to achieve. It was Kurt Lewin
(cited in Marrow, 1977) who said that there is nothing so
practical as a good theory. But to be “good,” a theory
must also be “practical.” In science, a good theory is one
that can be translated into corresponding research de-
signs that match the defining properties of the theory. In
the absence of such research designs—or worse yet, in
the application of research designs that fail to match or
even violate the defining properties of the theory—sci-
ence cannot move forward. Hence, we have sought, as we
proceed through successive stages of theoretical formula-
tion, to specify, and, wherever possible, to illustrate the
properties of a research design that corresponds with, or
at least approximates, the proposed theoretical structure.

DEFINING PROPERTIES OF TH E
BIOECOLOGICAL MODEL

An early critical element in the definition of the bioeco-
logical model is experience, which indicates that the
scientifically relevant features of an environment for
human development not only include its objective prop-

Def ining Properties of the Bioecological Model 797

erties but also the way in which the properties are sub-
jectively experienced by the person living in that envi-
ronment. This equal emphasis on an experiential as well
as an objective view springs neither from an antipathy to
behaviorist concept nor from a predilection for existen-
tial philosophic foundations but is dictated simply by the
fact that very few of the external inf luences signifi-
cantly affecting human behavior and development can
be described solely in objective physical conditions and
events (Bronfenbrenner & Evans 2000; Bronfenbrenner
& Morris 1998).

Critical to the foregoing formulation is the word
solely. In the bioecological model, both objective and
subjective elements are posited as driving the course of
human development; neither alone is presumed suffi-
cient. Moreover, these elements do not always operate in
the same direction. It is therefore important to under-
stand the nature of each of these two dynamic forces,
beginning on the phenomenological or experiential side.
Both of the terms are relevant because, while related to
each other, they are typically applied to somewhat dif-
ferent spheres. Experiential is more often used in rela-
tion to cognitive development and pertains mainly to
changes in how the environment is perceived at succes-
sive stages of the life course, beginning in early infancy
and proceeding through childhood, adolescence, adult-
hood, and, ultimately, old age.

By contrast, experience pertains more to the realm of
feelings—anticipations, forebodings, hopes, doubts, or
personal beliefs. Feelings, emerging in early childhood
and continuing through life, are characterized by both
stability and change: They can relate to self or to others,
especially to family, friends, and other close associates.
They can also apply to the activities in which we engage;
for example, those that we most or least like to do. But the
most distinctive feature of such experiential equalities is
that they are emotionally and motivationally loaded, en-
compassing both love and hate, joy and sorrow, curiosity
and boredom, desire and revulsion, often with both polar-
ities existing at the same time but usually in differing de-
grees. A significant body of research evidence indicates
that such positive and negative subjective forces, evolving
in the past, can also contribute in powerful ways to shap-
ing the course of development in the future (Bronfen-
brenner & Evans 2000; Bronfenbrenner & Morris 1998).

But these forces are not the only powerful ones at
work, other forces are more objective in nature. This
presence does not mean, however, that the forces are
necessarily either more or less inf luential, mainly be-

cause the two sets of forces are interdependent and af-
fect each other. Like their subjective counterparts, these
more objective factors also rely on their assessment of
corresponding theoretical models and associated re-
search designs, which evolved over time. These more
objective relationships are documented propositions
presented later (see too Bronfenbrenner & Evans 2000;
Bronfenbrenner & Morris 1998). The first proposition
specifies the theoretical model, and provides concrete
examples; the second foreshadows a corresponding re-
search design for their assessment.

However, before proceeding with formal definitions,
it may be useful to point out that traditionally such phe-
nomena as parent-child interaction—or, more generally,
the behavior of others toward the developing person—
have been treated under the more inclusive category of
the environment. In the bioecological model, a critical
distinction is made between the concepts of environ-
ment and process, with the latter not only occupying a
central position, but also having a meaning that is quite
specific. The construct appears in Proposition I stipulat-
ing the defining properties of the model. To place its
meaning in context, we cite Proposition II as well.

Proposition I

Especially in its early phases, but also throughout the life
course, human development takes place through processes
of progressively more complex reciprocal interaction be-
tween an active, evolving biopsychological human organism
and the persons, objects, and symbols in its immediate ex-
ternal environment. To be effective, the interaction must
occur on a fairly regular basis over extended periods of
time. Such enduring forms of interaction in the immediate
environment are referred to as proximal processes. Exam-
ples of enduring patterns of proximal process are found in
feeding or comforting a baby, playing with a young child,
child-child activities, group or solitary play, reading, learn-
ing new skills, athletic activities, problem solving, caring
for others in distress, making plans, performing complex
tasks, and acquiring new knowledge and know-how.

For the younger generation, participation in such in-
teractive processes over time generates the ability, moti-
vation, knowledge, and skill to engage in such activities
both with others and on your own. For example, through
progressively more complex interaction with their par-
ents, children increasingly become agents of their own
development, to be sure only in part.

798 The Bioecological Model of Human Development

Proximal processes are posited as the primary en-
gines of development (see Gottlieb, Wahlsten, & Lick-
liter, Chapter 5, this Handbook, this volume; Tobach,
1981; Tobach & Schneirla, 1968). A second defining
property, the fourfold source of these dynamic forces is
identified in Proposition II.

Proposition II

The form, power, content , and direction of the proximal
processes effecting development vary systematically as a
joint function of the characteristics of the developing per-
son, the environment—both immediate and more remote—
in which the processes are taking place, the nature of the
developmental outcomes under consideration, and the so-
cial continuities and changes occurring over time through
the life course and the historical period during which the
person has lived.

Propositions I and II are theoretically interdepend-
ent and subject to empirical test. An operational
research design that permits their simultaneous inves-
tigation is referred to as the Process-Person-Context-
Time (PPCT) model.

Characteristics of the person actually appear twice
in the bioecological model—first as one of the four ele-
ments inf luencing the form, power, content, and direction
of the proximal process, and then again as developmental
outcomes—qualities of the developing person that
emerge at a later point in time as the result of the joint,
interactive, mutually reinforcing effects of the four prin-
cipal antecedent components of the model. In sum, in the
bioecological model, the characteristics of the person
function both as an indirect producer and as a product of
development (see Lerner, 1982, 2002; Lerner & Busch-
Rossnagel, 1981).

Finally, because in the bioecological model the con-
cept of proximal process has a specific meaning, it is
important that its distinctive properties be made ex-
plicit. For present purposes, the following features of
the construct are especially noteworthy:

1. For development to occur, the person must engage in
an activity.

2. To be effective, the activity must take place “on a
fairly regular basis, over an extended period of
time.” For example, this means that with young chil-
dren, a weekend of doing things with Mom or Dad

does not do the job, nor do activities that are often
interrupted.

3. Why not? One reason is that, to be developmentally
effective, activities must continue long enough to
become “increasingly more complex.” Mere repeti-
tion does not work.

4. Developmentally effective proximal processes are
not unidirectional; there must be inf luence in
both directions. For interpersonal interaction, this
means that initiatives do not come from one side
only; there must be some degree of reciprocity in
the exchange.

5. Proximal processes are not limited to interactions
with people; they also can involve interaction with
objects and symbols. In the latter circumstance, for
reciprocal interaction to occur, the objects and sym-
bols in the immediate environment must be of a
kind that invites attention, exploration, manipulation,
elaboration, and imagination.

6. The powerful moderating factors specified in Propo-
sition II produce substantial changes in the content,
timing, and effectiveness of proximal processes. In
particular:

a. As children grow older, their developmental
capacities increase both in level and range;
therefore, to continue to be effective, the corre-
sponding proximal processes must also become
more extensive and complex to provide for the
future realization of evolving potentials. At the
same time, in view of the ongoing developmental
advance, the intervals between periods of “pro-
gressively more complex” activity can be in-
creasingly longer, although they must still occur
on a “ fairly regular basis.” Otherwise, the pace
of development slows, or its course may even
reverse direction.

b. The principal persons with whom young children
interact “on a fairly regular basis over extended
periods of time” are parents, but especially as
children get older, other persons—such as care-
givers, relatives, siblings, and peers—also func-
tion in this role. These are soon followed by
teachers or mentors in other activities, and then
by close friends of the same or opposite sex,
spouses or their equivalents, and coworkers, supe-
riors and subordinates at work. As the examples
indicate, the involvement of persons functioning

From Theory to Research Design: Operationalizing the Bioecological Model 799

in this role is not limited to the formative years.
Borrowing a term from G. H. Mead (1934), we
refer to such persons as significant others.

The foregoing constitute the principal elements of the
emergent theoretical model. If so, the question arises in
what sense is the model bioecological? Where and how
does biology come into the picture? We present three an-
swers to that question in an order of decreasing cer-
tainty about their validity. The first is an unqualified
disclaimer. Little in the pages that follow speaks to the
operation of biological systems within the organism.
By contrast, considerable scientific attention is ac-
corded to characteristics of the person generally re-
garded as biologically based that inf luence proximal
processes and their developmental outcomes. Finally,
the present model rests on the assumption that biologi-
cal factors and evolutionary processes not only set limits
on human development but also impose imperatives re-
garding the environmental conditions and experiences
required for the realization of human potentials. The po-
sition is taken that, to the extent that the necessary con-
ditions and experiences are not provided, such potentials
will remain unactualized (Bronfenbrenner & Ceci,
1993, 1994a, 1994b).

It is our belief that, when applied, the bioecological
paradigm is scientifically productive. At the present
time, however, its most distinguishing characteristic is
not its proven scientific power, but its rarity. To be sure,
the rarity is hardly surprising, given the fact that suc-
cessive revisions of the emerging model began to be
published only in the past several years ( Bronfenbren-
ner, 1989a, 1990, 1993, 1994, 1995; Bronfenbrenner &
Morris, 1998; Bronfenbrenner & Ceci, 1994a). Paradox-
ically, some concrete examples nevertheless existed
much earlier. They were the product of what Bronfen-
brenner and Crouter referred to in the 1983 edition of
this Handbook as “latent paradigms”; that is, theoretical
models that were not explicitly stated, but were implicit
in the research designs used in analyzing the data
(Bronfenbrenner & Crouter, 1983, pp. 373–376). In-
deed, a partial precursor of the bioecological model ap-
peared in the 1983 Handbook chapter under the rubric of
a “person-process-context model.” In that chapter, how-
ever, what is meant by process is never specified, and
the overwhelming majority of the examples cited do not
include a proximal process component as defined in
Proposition I. The same holds true for developmentally

relevant characteristics of the Person. The 1983 chapter
also made no reference to Time as a defining property of
the theoretical model. In these and other respects to fol-
low, today’s bioecological model goes far beyond its
predecessors both with respect to basic constructs and
their bidirectional, synergistic interrelationships.

FROM TH EORY TO RESEARCH DESIGN:
OPERATIONALIZING TH E
BIOECOLOGICAL MODEL

We have come to the point where it is both possible and
necessary to examine the requirements imposed by the
bioecological model for corresponding research designs.
We begin with a concrete example of the latter.

In the 1950s and 1960s, Cecil Mary Drillien (1957,
1964), a physician and professor of child life and health
at the University of Edinburgh, carried out a 7-year lon-
gitudinal investigation of psychological development in
two groups: 360 children of low birthweight and a con-
trol group selected “ by taking the next mature birth
from the hospital admission list ” (1957, p. 29). In her
follow-up assessments, the investigator found that chil-
dren of low birthweight were more likely to exhibit
problems in physical growth, susceptibility to illness,
impaired intellectual development, and poorer class-
room performance, with all of these tendencies being
more pronounced in boys (1964). In a comparison of
children’s school performance with what would have
been expected on the basis of their scores on an intelli-
gence test, Drillien found that those of low birthweight
were especially likely to be working below their mental
capacity. In relation to this finding, the author com-
ments as follows: “In most cases, failure to attain a stan-
dard commensurate with ability was associated with
problems of behavior, which were found to increase with
decreasing birthweight [and] to be more common in
males” (1964, p. 209).

Figure 14.1 depicts the results. The figure does not ap-
pear in Drillien’s monograph, but was constructed from
data presented in tables in that volume. It shows the im-
pact of the quality of mother-infant interaction at age 2
on the number of observed problem behaviors at age 4 as
a joint function of social class and three levels of low
birthweight—those underweight by a pound or more, not
more than one pound, and those of normal birthweight.
Measures of maternal responsiveness were based on

800 The Bioecological Model of Human Development

observations in the home and interviews with the mother.
The investigator’s measure of social class was a compos-
ite index that took into account not only parental income
and education but also the socioeconomic level of the
neighborhood in which the family lived. The quality of
interaction was assessed by extent to which the mother
was responsive to changes in the state and behavior of the
infant. The measure of the developmental outcome was
the frequency of reported behavior disturbances such as
hyperactivity, overdependence, timidity, and negativism.

Our primary interest is not in the research findings,
but in the extent to which the structure of the research de-
sign corresponds with the defining properties of the bioe-
cological theoretical model. The first point to be noted in
this regard is that Proposition I defines Proximal
Processes as bidirectional. Drillien’s measure of process,
however, was based only on the mother’s responsiveness
to changes in the state and behavior of the infant, and no
data are reported that would permit calculating a comple-
mentary measure of the infant’s responsiveness to
changes in the state and behavior of the mother. This
means that the operational measure available in Drillien’s
research taps only one side of the theoretical definition of
proximal process. For that reason, it appears likely that,
to the extent the infant’s contribution to reciprocal inter-
action carries any weight, the obtained results may un-
derestimate the true magnitude of the observed effects.

Nevertheless, as revealed in Figure 14.1, maternal re-
sponsiveness across time, a one-sided measure of proxi-

1 Synergism refers to “cooperative action of discrete agencies
such that the total effect is greater than the sum of the two or
more effects—taken independently ” (Webster’s Third New
International Dictionary).

mal process, still emerges as the most powerful predictor
of developmental outcome. In all instances, responsive
maternal treatment reduces substantially the degree of
behavioral disturbance exhibited by the child.

Herein lies the main justification for distinguishing
between proximal process on the one hand, and, on
the other, the environments in which the processes
occur; namely, in accord with Proposition I, proximal
processes turn out to be the most potent force inf luenc-
ing the developmental outcome (in this case, the fre-
quency of problem behaviors at 4 years of age).
Furthermore, as stipulated in Proposition II, the power
of the Process varies systematically as a function of the
environmental Context (i.e., social class) and of the
characteristics of the Person ( i.e., weight at birth). The
process appears to have made its greatest impact on
young children growing up in the most disadvantaged
environment (i.e., the lowest socioeconomic level), but
in that environment, it is those who at birth were of nor-
mal weight who benefited most. Moreover, it was in this
same disadvantaged Context that, under high levels of
maternal responsiveness, birthweight showed its most
consistent effect, with the number of behavior problems
steadily rising as birthweight fell. Finally, across the
board, maternal responsiveness had the general result of
decreasing or buffering against environmental differ-
ences in developmental outcome. Thus, at high levels of
mother-child interaction, social class differences in
problem behavior became much smaller.

From the perspective of developmental science, what
is most noteworthy about these findings is not their spe-
cific content but that their simultaneous discovery was
made possible by a research design based on a theoretical
model that allowed for the emergence of patterns of this
form. Not only are the four key components of Process,
Person, Context, and Time all represented but the design
also provides for the detection of the kinds of synergis-
tic1 interdependencies among these components that are
posited in the bioecological model as a dynamic theoret-
ical system. Two specific examples of such interdepen-
dencies are revealed in the analysis of Drillien’s data:

1. Proposition II stipulates that the developmental ef-
fects of proximal processes vary as a joint function of

Figure 14.1 Effect of mother’s responsiveness on problem
behavior of child at age 4 by birthweight and social class.

High SES Middle SES Low SES
Nrm Low Vlow Nrm Low Vlow Nrm Low Vlow

A
ve

ra
ge

S
co

re
o

n
B

eh
av

io
r

P
ro

bl
em

s
0
2
4
6
8
10
12

Nrm = Normal Birthweight
Low = Between Normal and 5.5 lbs.
Vlow = 5.5 lbs. or Less

Poor Process
Good Process

From Theory to Research Design: Operationalizing the Bioecological Model 801

Figure 14.2 Effect of mother’s responsiveness on problem
behavior of child at ages 2 and 4 by social class.

0
2
4
6
8
10

Age 2
High SES Mid SES Low SES

A
ve
ra
ge
S
co
re
o
n
B
eh
av
io
r
P
ro
bl
em
s

Age 4
High SES Mid SES Low SES

Poor Process—Unresponsive Mothers
Good Process—Responsive Mothers

Person and Context; that is, the indirect effects of
Person and Context on the relation of Process to out-
come are not to be conceived as simply additive.
Consistent with this expectation is the finding that
proximal processes had their greatest impact in the
most disadvantaged environment but on the healthiest
infant. The combination of Person and Context ex-
hibit a mutually reinforcing, multiplicative, indirect
effect on the power of proximal processes as the “en-
gines of development.”

2. In Drillien’s research, the frequency of problem be-
haviors was assessed at two points in time—first
when the infants were 2-years-old, and then again at
4-years-old. If one makes the not unreasonable as-
sumption that mothers continued to interact with
their children over the intervening period, then the
results shown in Figure 14.2 provide evidence for the
effect of proximal processes that have taken place
over an extended period of time. Youngsters experi-
encing low levels of interaction with their mothers
exhibited an accelerating increase in the number of
problem behaviors from 2 to 4 years of age, whereas
those exposed to substantially higher levels of this
proximal process showed only a modest rise.

Developmental Science in the Discovery Mode

What about the possibility that the preceding results are
chance findings? Some of them are statistically signifi-
cant, yet others could not be tested because the variances
needed for calculating error estimates were not reported.
But that is not the principal issue at stake. With concrete

examples of the relation between theoretical and opera-
tional models now before us, we can address what turns
out to be a complex and consequential question: What is
the function of research design in the bioecological
model? The first point to be made in this regard is that the
main function is not the usual one of testing for statistical
significance. Rather, the research design must provide for
carrying out an equally essential and necessarily prior
stage of the scientific process: that of developing hypothe-
ses of suf ficient explanatory power and precision to war-
rant being subjected to empirical test. We are dealing with
science in the discovery mode rather than in the mode of
verification. In this earlier phase, theory plays an even
more critical role. From its very beginnings, the bioeco-
logical model, through its successive reformulations, rep-
resents a sustained effort to meet this scientific need.

What are the appropriate characteristics of research
designs for developmental science in the discovery
mode? Finding an answer to this question is complicated
by the fact that, compared with the physical and natural
sciences, developmental science is admittedly still in an
earlier stage of development. Furthermore, because its
scope falls between the natural and the social sciences,
the discovery process must to some extent be adapted to
the requirements of both. Perhaps in part for these rea-
sons, we were unable to find any discussion of the issue
in the developmental literature. Under these circum-
stances, we concluded that the best we could do was to
try to make explicit the characteristics of the research
designs that had been employed over the past several
years to arrive at successively more differentiated for-
mulations of the bioecological model.

These design characteristics depend on the con-
structs, and the possible relations between them, that
are posited in the theoretical model at its present stage
of development. Both the constructs, and the possible in-
terrelationships, have been indicated in Propositions I
and II, but as yet they appear in a relatively undifferen-
tiated form. For example, the directions of the expected
effects of Person and Context on proximal processes for
different types of outcomes are not specified. The rea-
son for such lack of specificity is that a more precise
formulation could not be deduced either from the theory
in its present, still evolving state, or induced from any
already available data (at least, to our knowledge).
Given these limitations, we concluded that an appropri-
ate design strategy at this point in the discovery process
could be one that involves a series of progressively more
differentiated formulations and corresponding data

802 The Bioecological Model of Human Development

analyses, with the results at each successive step setting
the stage for the next round. The research designs em-
ployed must be primarily generative rather than confir-
matory versus disconfirming.

In this generative process, implications derived from
the theoretical model play a more prominent role than
those drawn from research findings, but the latter are
also critical. Their importance is best conveyed by spec-
ifying a key feature of the corresponding research de-
sign: It must provide a structured framework for
displaying the emergent research findings in a way that
reveals more precisely the pattern of the interdependen-
cies that are obtained in the data available. Of primary
scientific interest are not those aspects of the observed
pattern already anticipated in the existing theoretical
model, but those features that point to more differenti-
ated and precise theoretical formulations. These can
then be evaluated in the light of new evidence, and, if
deemed scientifically promising, can be incorporated in
the research design for a next step. The proposed strat-
egy for developmental investigations in the discovery
mode involves an iterative process of successive con-
frontations between theory and data leading toward the
ultimate goal of being able to formulate hypotheses that
both merit and are susceptible to scientific assessment
in the verification mode.

In presenting this definition of the discovery mode,
we acknowledge that, in actual scientific practice, it is
hardly likely to be a discovery. The process we have de-
scribed, or something like it, is what scientists have al-
ways done. Our primary reason for seeking to make that
process explicit was the belief that doing so could fur-
ther the discovery process. But we also hope that the ex-
plication and examples of the discovery mode presented
in this chapter will have broader utility in developmen-
tal research.

To return to the task at hand, the proposed criteria
have more specific implications for the critical role in
research design played by statistical analysis. First, in
the discovery phase, Type I errors can entail an even
greater risk than errors of Type II. To state the issue
more broadly, dismissing as invalid a finding that points
the way to a fuller and more precise explanation for the
phenomenon under investigation may result in a greater
loss than that produced by accepting a finding that is
highly significant because of as yet undifferentiated and
thereby confounded factors producing the phenomenon
in question (e.g., the failure to distinguish Process from
Context). The greater risk in the discovery process of

dismissing findings as Type I errors is further com-
pounded by the phenomenon of magnification of early
environmental differences over time. Thus, as illus-
trated by the escalating effects of proximal processes
shown in Figure 14.2, changes in outcome associated
with a proximal process at Time 1 can be quite small and
nonsignificant statistically. Yet, as shown, they can be
powerful predictors of a marked increase in develop-
mental outcome several years later (in the likely event
that the process continued to be maintained over the in-
tervening period).

At this point, a methodological note is in order. Sta-
tistical models widely used for the purpose of hypothe-
sis testing are often ill-suited as operational models for
developmental investigations in the discovery mode.
This is particularly true for models that control statis-
tically solely for linear relationships among the factors
in the research design to obtain an estimate of the inde-
pendent contribution of each factor in the statistical
model to the outcome under investigation. The validity
of such analyses rests on what in mathematical statis-
tics is referred to as “ the assumption of homogeneity of
regression.” To illustrate the assumption in its simplest
general case: given a dependent variable y and two in-
dependent variables x

1
and x

2
, then the relation be-

tween x
1

and y must be the same at all levels of x
2
. This

assumption is often not met in developmental data. For
example, when applied to the analysis shown in Figure
14.2, it would require that the relation between proxi-
mal process and frequency of problem behaviors be the
same at every social class level, which is not the case.
Nor is this requirement likely to hold with respect to
any combination of the four defining properties of the
bioecological model. As Bronfenbrenner stated in his
1979 monograph, “In ecological research, the principal
main ef fects are likely to be interactions” (p. 38, italics
in original).

Any research design based on a bioecological model
must allow for the possibility of such interactions. How-
ever, it is also essential, especially in the discovery
phase, that the particular interactions to be examined be
theoretically based, and that—if possible—their antici-
pated direction and form be specified in advance so that
discrepancies between theoretical expectation and ob-
served reality can be readily recognized and thus pro-
vide the basis for a next step in the typically slow,
iterative process of seeking more differentiated formu-
lations that merit further exploration both on theoretical
and empirical grounds. In each case, the new formula-

From Theory to Research Design: Operationalizing the Bioecological Model 803

tion should be consistent with the existing theoretical
specifications of the bioecological model, but it also
must take into account any old or new research findings
bearing on the issue.

The foregoing criteria for research in the discovery
mode do not imply neglect of the traditional issues of re-
liability and validity. These are honored in a somewhat
different, theoretically guided way. Essentially, the pro-
cess is one of cross-validation at two levels. First, in a
given study, the results at each successive stage of analy-
sis are validated in the next, more differentiated formula-
tion. Second, the generalizations emerging from a given
investigation are cross-validated against findings from
other studies of theoretically related phenomena but with
a specific focus on the defining components of the bioe-
cological model.

Before we proceed with concrete examples, it is im-
portant to emphasize that the criteria we have proposed
and applied for conducting developmental science in the
discovery mode represent a first attempt to construct a
working model. Moreover, the working model is subject
to the curious qualification that it is itself the product of
the same sequential design that it proposes. The criteria
were developed by examining the changes introduced at
each successive stage in the evolution of the bioecological
model to identify the theoretical and operational proper-
ties leading to improvement in the model’s predictive
power. The example that follows illustrates these concur-
rent processes.

Dif ferent Paths to Dif ferent Outcomes:
Dysfunction versus Competence

In this instance, our exploratory effort took as its point of
departure the stipulation in Proposition II that the effects
of proximal processes vary systematically depending on
the developmental outcome. Once again, rather than tak-
ing time to retrace our steps, we begin with where we
ended up; namely, with the following initial formulation:

The greater developmental impact of proximal processes
on children growing up in disadvantaged or disorganized
environments is to be expected to occur mainly for out-
comes ref lecting developmental dysfunction. By contrast ,
for outcomes indicating developmental competence, proxi-
mal processes are posited as likely to have greater impact
in more advantaged and stable environments.

The term dysfunction refers to the recurrent manifes-
tation of difficulties on the part of the developing per-
son in maintaining control and integration of behavior

across situations, whereas competence is defined as the
demonstrated acquisition and further development of
knowledge and skills—whether intellectual, physical,
socioemotional, or a combination of them (e.g., learning
how to care for a young infant involves all three).

The preceding emergent formulation is based on the
following considerations. Most parents have the capac-
ity and the motivation to respond to manifestations
of physical or psychological distress on the part of
their children. In deprived or disorganized environ-
ments, such manifestations of dysfunction have been
shown to be both more frequent and more severe (e.g.,
in Drillien’s research), thus drawing on more of par-
ents’ available time and energy. Accordingly, to the
extent that , in disadvantaged settings, parents are able
to engage in proximal processes, these are likely to
have greater impact in reducing dysfunction rather
than in enhancing their children’s knowledge about
and skill in dealing with the external environment.
With respect to problems of dysfunction, in deprived
environments there is usually a match between young
children’s needs and their parents’ capacity to meet
those needs. This does not mean, however, that chil-
dren in such environments will end up functioning as
well as their age-mates growing up in more favorable
circumstance, but rather that , over similar periods of
time, they will show greater improvement in control
over their own problem behaviors as a function of
parental responsiveness.

The situation in advantaged and stable environments
is rather different. Manifestations of dysfunction are
likely to occur less often and to be less intense. Under
these circumstances, parents are more apt to be at-
tracted by and respond to the more frequent and more
gratifying signs of their children’s growing competence,
with the result that proximal processes may to be fo-
cused mainly in this latter sphere. In addition, parents
living in a middle-class world are themselves more apt
to possess and exhibit the knowledge and skills they
wish their children to acquire. They also have greater
access to resources and opportunities outside the family
that can provide needed experiences for their children.
Taken together, the foregoing considerations led to the
formulation of the previously stated “proto-hypothesis.”

Because Drillien’s study of the inf luence of mother-in-
fant interaction dealt with only one developmental out-
come, one has to look elsewhere for evidence that effects
of such processes vary depending on the nature of the out-
come under consideration. A rich data archive generously

804 The Bioecological Model of Human Development

Figure 14.3 Effect of parental monitoring on grades in
high school by family structure and mother’s level of educa-
tion. Analyses and graph based on data archives generously
provided by Professors Stephen A. Small ( University of Wis-
consin) and Tom Luster ( Michigan State University).

Levels of Parental Monitoring Ranging from 0–12

20 4 6 8 10 12
31 5 7 9 11

M 20 4 6 8 10 12
31 5 7 9 11

M 20 4 6 8 10 12
31 5 7 9 11

M
2.9

3.9

4.9

5.9

6.9

G
ra

de
P

oi
nt

A
ve

ra
ge

(
G

PA
)

Mother and
Father

Single–Parent Mother

Mother and
Stepfather

Mothers with some education beyond high school
Mothers with no education beyond high school

GPA Scale:
2 = Mostly D’s or less 6 = Mostly B’s
3 = 1/2 C’s, 1/2 D’s 7 = 1/2 A’s, 1/2 B’s
4 = Mostly C’s 8 = Mostly A’s
5 = 1/2 B’s, 1/2 C’s

Mean

Mean
Mean

into a closely corresponding research design can produce reli-
able f indings even when there are relatively few cases in
some, or even all, the cells of the model. This comes about be-
cause, in effect , the bioecological model requires, in its dis-
covery phase, advance specif ication primarily not only of
main effects but also in the form and direction of their most
plausible interactions in the light of both the evolving theoret-
ical model and the then available research evidence. This is
especially true for well-designed experiments. For examples,
see pp. 808–809.

made available by Small and Luster (1990) from their
statewide studies of youth at risk in Wisconsin met this
need.2 Figure 14.3 depicts the results from an analysis of
the differential effects of parental monitoring on the aca-
demic achievement of high school students living in one of
the three most common family structures found in the
total sample of over 2,500 cases.3 The students were be-
tween 14 and 16 years of age. It was also possible to strat-
ify the sample by two levels of mother’s education, with
completion of high school as the dividing line. Parental
monitoring refers to the effort by parents to keep in-

formed about and set limits on their children’s activities
outside the home. In the present study, it was assessed by
a series of items in a questionnaire administered to ado-
lescents in their school classes. All items referred to par-
ents in the plural, with no distinction as to whether the
mother or the father was doing the monitoring. Levels of
parental monitoring, ranging from 0 to 12, are shown on
the horizontal axis, and grade point average (GPA) is
shown on the vertical. The markers to the right of each
curve record the mean GPA for each of the six groups.

Once again, the results reveal that the effects of prox-
imal processes are more powerful than those of the
environmental Contexts in which they occur. In this in-
stance, however, the impact of the Process was greatest
in what emerges as the most advantaged ecological
niche—families with two biological parents in which the
mother had some education beyond high school. More-
over, the developmental effect of the proximal process on
school grades—a measure of competence—was stronger
for families living in more advantaged socioeconomic
circumstances. This finding is directly opposite to that
revealed by the analysis of Drillien’s data, where the out-
come was one of psychological dysfunction (i.e., the fre-
quency of problem behaviors). At the same time, the
principal finding from both studies documents the power-
ful effect of proximal processes on human development,
a result consistent with the first defining property of the
bioecological model stipulated in Proposition I.

The reader may well ask why the data in each scatter-
gram were fitted to a curve with a declining slope rather
than simply with a straight line. In accord with the crite-
ria for research in the discovery mode, the introduction of
the quadratic term was based on theoretical considera-
tions. Higher levels of academic performance require
mastery of more complex tasks, and hence are more diffi-
cult to achieve. As a result, at each successive step, the
same degree of active effort would be expected to yield a
somewhat smaller result. More specifically, for pupils
who are not doing so well in school, parental monitoring

2 The analyses of data from the Wisconsin archive reported in
this chapter were carried out in collaboration with Stephen A.
Small ( University of Wisconsin) and Tom Luster ( Michigan
State University) who designed and conducted the survey
from which the data are drawn. We are deeply indebted to
them for the theoretical thinking that underlies the construc-
tion of the survey. It is an excellent example of developmental
science in the discovery mode. We are also grateful to Regina
Cannon (then a graduate student at Cornell University) who
carried out the statistical analyses with care and dispatch.
3 The large number of cases in this study should not be taken
to imply that the bioecological model can be applied only in
samples with a large N. As illustrated here, precision in the
formulation of the theoretical model and in its translation

From Theory to Research Design: Operationalizing the Bioecological Model 805

can have a substantial effect by ensuring more stability of
Time and place so that some learning can occur. But for
superior school achievement, students would require in
addition high levels of motivation, focused attention,
prior knowledge, and—especially—actually working
with the material to be learned. These are all qualities
that stability of Time and place by itself cannot provide.

As can be seen in Figure 14.3, the relation between
parental monitoring and school grades shows a curvilin-
ear trend. Moreover, in accord with criteria for research
in the discovery mode (see pp. 801–803), both in its di-
rection and form the trend corresponds with theoretical
expectations in being more pronounced when the mother
has some education beyond high school, especially in a
two-parent family structure. A test for heterogeneity of
regression confirms visual inspection. The differences in
slopes between the two educational levels are highly sig-
nificant (p ≤ .01), with the quadratic component emerg-
ing as reliable only in the higher educational group.4 Also
statistically significant are differences in school achieve-
ment by family structure in each level of mother’s educa-
tion, with students growing up in two-parent families
getting the highest grades, and those from single-parent
families the lowest, a rank order corresponding to the
power of the proximal process in each group as measured
by the slopes of the associated regression coefficients.

Finally, a result not shown on the graph provides addi-
tional evidence pointing to another tentative generaliza-
tion. The first indication appeared in the analysis of
Drillien’s data, which, among other findings, revealed
that maternal responsiveness had the general effect of de-
creasing or buffering against environmental differences in
developmental outcome. Thus, at high levels of mother-
child interaction, social class differences in problem be-
havior became smaller. A similar pattern emerges for the
effects of parental monitoring on school grades. Across
the six groups shown in Figure 14.3, stronger parental
monitoring was associated not only with a higher mean
on school performance but also with a lower standard de-
viation. These differences, too, were statistically reliable.
Hence the following working hypothesis:

For outcomes of competence, proximal processes not only
lead to higher levels of developmental functioning but also

serve to reduce and act as a buffer against effects of dis-
advantaged and disruptive environments.

To turn from substance to method, the foregoing
findings also demonstrate that tests of significance have
a place in research in the discovery mode, but, as with
hypothesis verification, only after a specific theoretical
expectation has been formulated in advance.

In a discovery context, however, the aim is not to
claim empirical validity for a particular theoretical for-
mulation but to indicate its plausibility for inclusion in
the research design at subsequent stages of exploratory
work. To be sure, doing so may result in a failure of
replication. But not doing so risks missing potentially
important, theoretically guided research opportunities
not yet recognized. Garmezy and Rutter (1983), in their
landmark studies of stress and coping in children’s
development, did not differentiate between those protec-
tive or disruptive forces emanating from the environ-
ment, and those inherent in the biopsychological
characteristics of the person. As evidenced from the
analysis of Drillien’s data shown in Figure 14.1, these
vectors do not always operate in the same direction.
Nevertheless, Garmezy and Rutter’s formulations and
findings played a significant role in the early stages of
the process through which the bioecological model
reached its present, still-evolving form.

The still-evolving form imposes the obligation to take
advantage of existing opportunities for continued explo-
ration. With respect to the present inquiry, the next step in
that process was once again to pose the question about the
extent to which the research design meets the defining
properties of the bioecological model. At first glance, we
appear to be confronted with the same problem that we en-
countered with Drillien’s study. Proposition I defines
proximal processes as bidirectional. As previously noted,
Small and Luster (1990) defined parental monitoring as
the effort by parents to keep informed about and set limits
on their children’s activities outside the home. As stated,
such behavior implies inf luence from one side only—that
of the parents. An examination of the actual items used in
their questionnaire, however, revealed that they were of
two kinds. Some were cast in the language of parental ex-
pectation and prescription (e.g., “If I am going to be home
late, I am expected to call my parent(s) to let them know”;
“ When I go out, my parent(s) ask me where I’m going”).
By contrast, other items implied that the desired expecta-
tions or prescriptions were being met (e.g., “My parent(s)
know where I am after school”; “I tell my parent(s) who

4 The degree of curvilinearity is measured by the correspon-
ding regression coeff icients and not by difference in the
length of each curve from top to bottom. The latter is deter-
mined by empty cells in the scatter plot below or above which
entries for both monitoring level and GPA were available.

806 The Bioecological Model of Human Development

Figure 14.4 Parental monitoring and high school grades by
gender : mothers with more than a high school education.
Analyses and graph based on data archives generously pro-
vided by Professors Stephen A. Small ( University of Wiscon-
sin) and Tom Luster ( Michigan State University).

2-Parent
Family

MeanMean

2
3
4
5
6
7
A
ve
ra
ge

G
ra

de
i

n
H

ig
h

S
ch

oo
l

S
ub

je
ct

s

Boys

Mean

Mean
Mean
Mother and
Stepfather

Single-Parent
Mother

Girls

2
0 4

6

8
10

12
2

0 4
6

8
10
12
2
0 4
6
8
10
12
2
0 4
6
8
10

122
0 4

6
8
10

12
2
0 4
6
8
10

12
Level of Parental Monitoring

Mean
Girls
Boys

Boys Girls

Mean
Mean

High school students are between 14 and 16 years old.

5 Within each pair, both means and regression coeff icients
were statistically signif icant , the latter conf irming reliable
differences in slope.

I’m going to be with before I go out ”). Although the first
type of item is unidirectional, the second entails some de-
gree of reciprocity to the extent that the adolescent is
providing the information desired by the parents. Accord-
ingly, we hypothesized that items of the second type
would show stronger relationships to developmental out-
comes than those that described only the parents’ expecta-
tions of how they wished their children to behave.

Separate analyses of scales based on each type of
item provided substantial support for our working hy-
pothesis. Although responses to both types of questions
showed reliable effects on school performance, the rela-
tionships for the reciprocity scale were significantly
stronger and were much more likely to show curvilinear
effects. Accordingly, the latter was the scale used in an-
alyzing the results presented in Figure 14.3.

From the perspective of the biological model, the re-
search design producing the results shown in that figure is
missing an important Person component. It is a general
finding in educational research that at the high school
level female students score higher on measures of aca-
demic performance than do males. The question therefore
arises: To what extent is this gender difference attributa-
ble to variations in proximal process? Figure 14.4 pro-
vides a tentative answer to this question for students
whose mothers had more than a high school education. In
each family structure, parental monitoring exerted a more
powerful effect on the school achievement of girls than of

boys, a result that is paralleled by corresponding differ-
ences in average GPA for the two sexes.5 In each of the
three family structures, girls received higher grades than
boys, with the difference being most pronounced in two-
parent households and lowest in single-mother families.

As seen in Figure 14.4, however, a distinctive feature
of the pattern for girls is a marked f lattening
of the curve, especially for daughters of single-parent
mothers. This result suggests that, in each of the
three family structures, mothers may be pushing their
already successful daughters to the point where con-
formity to maternal control no longer brings educational
returns, particularly when the mother is the only parent.

An analysis of data on students whose mothers had
no more than a high school education showed a similar
general pattern, but the effects were less pronounced.
The inf luence of monitoring was appreciably weaker,
and its greater benefit to girls was also reduced. Never-
theless, girls with less-educated mothers both in single-
parent and in stepfamilies still had higher GPA scores
than boys. This means that some other factor not yet
identified must account for this difference.

Although a number of possibilities come to mind re-
garding this unknown, regrettably the Wisconsin archive
does not contain any data on the principal suspects. What
is available is information about another trail of discovery
that we have already begun to explore. Our successively
more differentiated working models, both conceptual and
operational, for assessing the effects of parental monitor-
ing on school achievement have provided increasing sup-
port for the tentative hypothesis that, for outcomes
ref lecting developmental competence, proximal processes
are likely to have greatest impact in the most advantaged
environments. But what about the other half of the original
formulation: the complementary postulate that the greater
developmental impact of proximal processes growing up
in poor environments is to be expected to occur mainly for
outcomes ref lecting developmental dysfunction?

Data from Small and Luster’s archive also provide
the opportunity for cross-validating this provisional
claim. In addition to measures of academic achievement,
the Wisconsin study also included information on
teenagers’ sexual activity. The decision to analyze this
outcome in the context of a bioecological model was
prompted by Small and Luster’s (1990) finding that such

From Theory to Research Design: Operationalizing the Bioecological Model 807

Figure 14.5 Effect of monitoring on girls’ sexual activity
( high school students between 14 and 16 years of age).

21 3 4

Mother Completed
High School Only

Mother Had Some Education
Beyond High School

21 3 4
20

40

60

80

Mean
Mean

P
er

ce
nt

S
ex

ua
ll

y
A

ct
iv

e
0

Daughter with Own Mother and Father

Daughter with Mother and Stepfather
Daughter with a Single-Parent Mother

6 We are also indebted to Kristen Jacobson, now a doctoral
student at Pennsylvania State University, for her ingenuity
and accuracy in translating into a common format data
archives recorded on different computing systems.

behavior varied systematically by family structure. Sex-
ual activity was measured by a single question: “Have
you ever had sexual relations with another person?”

This documentation of variations in sexual activity
by family structure takes on special significance in the
light of broader social changes taking place in the lives
of children, youth, and families in contemporary U.S.
society. Today, the United States has the highest rate of
teenage pregnancy of any developed nation, almost
twice as high as that of its nearest competitors (Bron-
fenbrenner, McClelland, Wethington, Moen, & Ceci,
1996, p. 117). Adolescent sexual activity is also one of
the prominent elements in the so-called teenage syn-
drome, an escalating pattern of co-occurring behaviors
including smoking, drinking, early and frequent sexual
experience, adolescent pregnancy, a cynical attitude to-
ward education and work, and, in the more extreme
cases, drugs, suicide, vandalism, violence, and criminal
acts (for references and successive summaries of the ev-
idence, see Bronfenbrenner, 1970, 1975, 1986a, 1989c,
1990, 1992; Bronfenbrenner et al., 1996; Bronfenbren-
ner & Neville, 1994).

In anticipating the effects of parental monitoring on
teenagers’ sexual activity, we were again confronted
with the issue of the possible direction of inf luence. In
relation to sexual activity as an outcome, however, some
leverage for the resolution of the issue was provided be-
cause each direction could be expected to produce oppo-
site effects. On the one hand, if parental monitoring
functions to defer sexual activity, then the more moni-
toring the less sexual activity. On the other hand, if the
parents begin to monitor only after the fact, the associa-
tion would be reversed, with monitoring occurring in re-
action to the adolescent’s behavior; hence, sexually
active adolescents would be monitored more.

The results of the analysis are shown in Figures 14.5
and 14.6.6 The most salient finding for both sexes is that
parental monitoring does substantially reduce adoles-
cents’ sexual activity. In many other respects, however,
the patterns for female and male adolescents are quite
different. The results for girls in Figure 14.5 show that
the effect of parental monitoring is stronger for daugh-
ters of mothers with no education beyond high school—
a finding consistent with the working hypothesis

that, for outcomes ref lecting lack of control, proximal
processes have greater impact in poorer environments.
Tests for heterogeneity of regression confirm that this
finding holds for each of the three family forms.

Yet, as shown in Figure 14.6, the corresponding analy-
sis of the data for boys reveals the very opposite result.
Parental monitoring has a more powerful effect on boys
whose mothers have had more education rather than less.
Once again, the finding holds in each family structure
and is confirmed by tests for heterogeneity of regression.

Figure 14.6 Effect of parental monitoring on boys’ sexual
activity ( high school students between 14 and 16 years of age).

21 3 4 21 3 4

20
40
60
80
P
er
ce
nt
S
ex
ua
ll
y
A
ct
iv
e
0
Mother Completed
High School Only
Mother Had Some Education
Beyond High School

Group %

Sons in Biological Families

Sons in Stepfamilies
Sons of Single-Parent Mother

Group %

808 The Bioecological Model of Human Development

This is not the only departure from the expecta-
tions generated by the most recent working model. For
example, there was not always correspondence between
the developmental power of proximal processes in a
given family structure and the percentage of sexually
active adolescents in that structure: In stepfamilies in
which the mother has only a high school education, ma-
ternal monitoring of daughters is as high as it is in two-
parent families, but the percentage of sexually active
girls is even greater than that for single-parent mothers
at the same educational level. The finding is consistent
with research indicating that living in a family with a
stepfather entails a special developmental risk for girls
(Hetherington & Clingempeel, 1992).

And so, we find ourselves engaged in a next stage of the
discovery process in which we are seeking to develop a
more differentiated formulation that, through a corre-
sponding research design, will be most effective in reduc-
ing the observed empirical departures from expectations
based on the existing working model. The first step is to
ask an obvious question: What is most likely to account
for such discrepancies? Restating the question from the
perspective of the bioecological model, which of the four
components is a likely suspect? It has to be somebody who
is already on the scene. Parents are already there. Who
else is around who could exert some inf luence on the sex-
ual activity of high school students? The question answers
itself—the peer group. And if it is indeed true that proxi-
mal processes are at least as powerful determinants of de-
velopment as either the characteristics of the person or of
the environment, what might that process be?

A tentative first nomination is progressively more in-
tense interaction with peers who are already sexually ac-
tive. Among other considerations, this suggestion is guided
by the possibility that peer pressure to engage in sexual ac-
tivity and the prestige that such activity brings are likely to
be higher for boys from less educated families with the re-
sult that parental monitoring is not as effective. With re-
spect to the other components in the model, given the
findings just reported, gender would still be a Person char-
acteristic of major importance. The choice of an appropri-
ate environmental Context depends on the precise research
question being asked. Family structure would also still be
appropriate. But from the perspective of the bioecological
model, an option to consider would be the parents’ beliefs
about the activities they wanted their adolescent son or
daughter to engage in or refrain from, as well as the close-
ness of the parent-child relationship.

We offer these suggestions not for their relevance to
this particular issue but to illustrate two additional emer-
gent corollaries of the bioecological model:

1. The specific components of Process, Person, Con-
text, and Time to be included in a given investigation
should be those that, from a theoretical perspective,
are maximally relevant to the research question under
investigation and complementary to each other in re-
lation to the given developmental outcome.

2. From a theoretical perspective, the power of a PPCT
design is most effectively enhanced by including more
than one proximal process in the model.

The next section leads to yet another corollary.

The Role of Experiments in the
Bioecological Model

The examples considered thus far are essentially
experiments of nature: They show how development is
inf luenced by variations in the components of the bioe-
cological model occurring in already existing societies.
They tell us nothing about whether, to what extent, or
how these elements and their combinations can be
changed. This limitation applies particularly to the most
consequential component of the bioecological model—
proximal processes. We know of no research bearing
specifically on this question, but some indirect evidence
does exist. In research findings already presented, im-
proving the quality of the environment has been shown to
increase the developmental power of proximal processes.
The indirect evidence comes from experiments in which
researchers have systematically introduced conditions
into the environment in which people lived that were hy-
pothesized to enhance their psychological functioning
beyond existing levels.

Here are two examples at contrasting ages.

Environmental Dynamics in Old Age

The first example is Langer and Rodin’s oft-cited exper-
imental intervention conducted with residents of a New
Haven nursing home for the aged (Langer & Rodin, 1976;
Rodin & Langer, 1977). The contextual manipulation
employed in this study is well summarized in the au-
thors’ words:

From Theory to Research Design: Operationalizing the Bioecological Model 809

The hospital administrator gave a talk to residents in the
experimental group emphasizing their responsibility for
themselves, whereas the communication to a second, com-
parison group stressed the staff ’s responsibility for them
as patients. To bolster the communication, residents in the
experimental group were offered plants to care for,
whereas residents in the comparison group were given
plants that were watered by the staff. ( Rodin & Langer,
1977, p. 897 )

Residents were assigned at random to either the exper-
imental or the control group. Data on psychological and
health characteristics were collected at three time points:
(1) just prior to the introduction of the experiment; (2) 3
weeks later, when the experiment was formally ended;
and (3) in a follow-up study conducted 18 months later.

The substantial effects of intervention found at the
end of the experiment (Langer & Rodin, 1976) were still
in evidence in the follow-up assessment. To be sure, be-
cause the residents were almost a year-and-a-half older,
the added age had taken some toll, but, nevertheless,
those in the “induced responsibility” group not only sig-
nificantly surpassed their controls, but were appreciably
better off, both psychologically and physically, than
they had been months earlier before the intervention had
begun. In ratings by observers blind to the experimental
conditions, they were judged to be more alert, sociable,
and vigorous. The most striking results were seen in the
comparison of death rates between the two treatment
groups. Taking the 18 months prior to the original inter-
vention as an arbitrary comparison period, in the subse-
quent 18 months following the intervention, 15% in the
“responsibility-induced” group died, compared with
30% in the control group.

Environmental Dynamics in Infancy

A remarkable, independent cross-validation of Langer and
Rodin’s principal hypothesis appears in the findings of
another intervention experiment—this one almost un-
known—that was carried out at about the same time with a
sample of 100 9-month-old infants and their mothers in
the Dutch city of Nijmegen (Riksen-Walraven, 1978). Al-
though this author, Marianne Riksen-Walraven, appears
not to have been aware of Langer and Rodin’s work con-
ducted during the same period, one of the two interven-
tion strategies she employed with her sample of infants
was similar to that used in the New Haven study of elderly
patients. Mothers, randomly assigned to what Riksen-
Walraven called the “responsiveness” group, were given a

“ workbook for parents” stressing the idea that “ the infant
learns most from the effects of its own behavior ” (p. 113):

Caregivers were advised not to direct the child’s activities
too much, but to give the child opportunity to f ind out
things for himself, to praise him for his efforts, and to re-
spond to his initiations of interaction. ( p. 113)

By contrast, mothers of infants in the “stimulation”
group received a workbook that emphasized the impor-
tance of providing the infant with a great variety of per-
ceptual experiences of all kinds, “ to point to and name
objects and persons,” and “ to speak a lot to their in-
fants” (p. 112).

In the follow-up assessment conducted 3 months later,
infants of mothers who had been encouraged to be re-
sponsive to their babies’ initiatives exhibited higher lev-
els of exploratory behavior and were more likely to prefer
a novel object to one that was already familiar. The babies
also learned more quickly in a learning contingency task.

Neither of the preceding investigations included
any systematic assessment of the activities in which the
participants in the experiment subsequently engaged, of
the balance between unidirectional and bidirectional be-
havior in the two groups, or of any other specific feature
that could provide a measure of the extent to which prox-
imal processes were operating in each of the two con-
trasting experimental conditions.

In both of the preceding experimental studies,
elegant as they are, the keystone of the bioecological
model—a measure of proximal process—was not in-
cluded in the research design. In addition, the demonstra-
tion (in Figure 14.3) of the joint, indirect effects of
family structure and parents’ education on the relation of
proximal processes to school grades does only half the
job, for it provides no information on whether differences
in students’ personal characteristics (such as gender)
exert a similar indirect effect. Nevertheless, viewed from
the theoretical perspective of a bioecological model, all
these findings are impressively consistent with expecta-
tions derived from the model; the findings illustrate the
model’s practicability, and—perhaps most promising for
the future of developmental science—generate questions
that, when answered, provide ways for enhancing the
model’s scientific power. It is these questions and an-
swers that are addressed in the following sections.

Up to this point, our exposition has given primary at-
tention to the core concept of proximal process and its

810 The Bioecological Model of Human Development

key position in the bioecological model as a whole. We
now proceed to a more detailed examination of each of
the other three defining properties of the model—Per-
son, Context, and Time.

HOW DO PERSON CHARACTERISTICS
INFLUENCE LATER DEVELOPMENT?

As already indicated, at midstage in the development of
the bioecological model, an effort was begun to arrive at
some answers to this question, and it has continued up to
the present day. As before, rather than describe the suc-
cessive stages in this emergent reconception, we present
it in its most recent, still-evolving form.

Most developmental research treats the cognitive and
socioemotional characteristics of the person as dependent
variables; that is, as measures of developmental outcomes.
Far less often are such characteristics examined as pre-
cursors and producers of later development From the per-
spective of the bioecological model, their effectiveness in
the latter role derives from their capacity to inf luence the
emergence and operation of proximal processes.

Accordingly, in an effort to identify such process-rel-
evant Person characteristics, we applied the sequential
design strategy described in the preceding section. Be-
ginning with implications derived from the theoretical
model, which are then related to existing research find-
ings, successive applications of this strategy have re-
sulted in the conceptualization of three kinds of
process-relevant Person characteristics, which, for con-
venience of brevity, we have labeled as Person forces, re-
sources, and demands.7

Force Characteristics as Shapers
of Development

In the bioecological model, the characteristics of the
Person most likely to inf luence future development
would be active behavioral dispositions that can set
proximal processes in motion and sustain their opera-
tion, or—conversely—actively interfere with, retard, or
even prevent their occurrence. It is therefore useful to

distinguish between these two propensities. We refer to
the former as developmentally generative characteristics;
to the latter as developmentally disruptive.

Examples of developmentally disruptive dispositions
come more readily to mind. At one pole, they include
such characteristics as impulsiveness, explosiveness, dis-
tractibility, inability to defer gratification, or, in a more
extreme form, ready resort to aggression and violence; in
short, difficulties in maintaining control over emotions
and behavior. At the opposite pole are such Person attri-
butes as apathy, inattentiveness, unresponsiveness, lack
of interest in the surroundings, feelings of insecurity,
shyness, or a general tendency to avoid or withdraw from
activity.8 Persons exhibiting either of the preceding
propensities would find it difficult to engage in proximal
processes requiring progressively more complex patterns
of reciprocal interaction over extended periods of time.

By contrast, developmentally generative characteris-
tics involve such active orientations as curiosity, tendency
to initiate and engage in activity alone or with others, re-
sponsiveness to initiatives by others, and readiness to
defer immediate gratification to pursue long-term goals.

We have found few investigations that shed light on the
developmental effects of either type of dynamic character-
istics on proximal processes and their outcomes. A major
reason for this shortcoming is the absence of theoretical
constructs for conceptualizing their changing nature over
the course of development from early infancy, through
adolescence, into and beyond early adulthood. The follow-
ing framework is offered as an initial basis for meeting this
requirement beginning in the Person domain in greater
need of conceptual definition—that of developmentally
generative characteristics. The corresponding structure
for developmentally disruptive Person qualities can then
be derived as an inverted mirror image of the former.9

Developmentally Generative Dispositions in
Life-Course Perspective

The first and earliest manifestation of generative dispo-
sitions takes the form of what we call selective respon-
siveness. It involves differentiated response to, attraction
by, and exploration of aspects of the physical and social
environment.

7 As is documented later in this chapter ( p. 819), the recently
renewed, and far stronger, claims by behavior geneticists for
the predominant role of genetic factors in determining both
individual and group differences in all forms of human char-
acteristics are directly challenged by alternative explanations
and research f indings derived from the bioecological model.

8 Depending on the available alternatives, withdrawal may be
the only course left for dealing with an unbearable situation.
9 The material that follows represents a further development
by the present authors of ideas f irst introduced in Bronfen-
brenner (1989).

How Do Person Characteristics Inf luence Later Development? 811

The next generative characteristic to evolve goes be-
yond selective responsiveness to include the tendency to
engage and persist in progressively more complex activ-
ities; for example, to elaborate, restructure, and even to
create new features in our environment—not only physi-
cal and social but also symbolic. We refer to propensi-
ties of this kind as structuring proclivities.

The transition from one to the other of these dynamic
forms of orientation during early childhood is illustrated
in successive publications from a longitudinal study of in-
fants being carried out by Leila Beckwith, Sarale Cohen,
Claire Kopp, and Arthur Parmelee at UCLA (Beckwith &
Cohen, 1984; Beckwith, Rodning, & Cohen, 1992; Cohen
& Beckwith, 1979; Cohen, Beckwith, & Parmelee, 1978;
Cohen & Parmelee, 1983; Cohen, Parmelee, Beckwith, &
Sigman, 1986). Their imaginative and careful work re-
veals a progressive sequence of such environmentally ori-
ented dispositions from birth through 7 years of age.
Thus, immediately after birth, infants are especially re-
sponsive to vestibular stimulation ( being picked up and
held in a vertical position close to the body), which has
the effect of soothing babies so that they begin to engage
in mutual gazing; by 3 months, visual exploration extends
beyond proximal objects, and the mother’s voice is most
likely to elicit responses especially in the form of recipro-
cal vocalizations.

From about 6 months on, the infant begins actively to
manipulate objects spontaneously in a purposeful way
and to rearrange the physical environment. By now, both
vocalization and gesture are being used to attract the
parents’ attention and to inf luence their behavior. In ad-
dition, there is a growing readiness, across modalities,
to initiate and sustain reciprocal interaction with a
widening circle of persons in the child’s immediate en-
vironment. This is the emergence of what we call struc-
turing proclivities.

A number of other investigations have yielded com-
parable findings, and have extended them to still other
activity domains; for example: individual differences in
children’s creativity in play and fantasy behavior (Con-
nolly & Doyle, 1984; MacDonald & Parke, 1984) or
Jean and Jack Block’s longitudinal studies of “ego re-
siliency” and “ego control” (J. H. Block & Block, 1980;
J. Block, Block, & Keyes, 1988).

The nature of the third and final class of develop-
mentally generative Person characteristics ref lects the
increasing capacity and active propensity of children
as they grow older to conceptualize their experience. It
deals with what we call directive belief systems about

oneself as an active agent both in relation to the self
and environment, or, for short, directive beliefs. The
oldest concept of this kind is Rotter’s construct and
measure of “locus of control” (Rotter, 1966). Subse-
quently, a more sophisticated formulation of the con-
cept was introduced by Bandura (1977, 1982) under the
rubric of self-efficacy. The principal distinction be-
tween these earlier constructs and their counterparts in
the bioecological model is that the latter are conceptu-
alized primarily not as characteristics of the person
sufficient unto themselves but as directional disposi-
tions interacting synergistically with particular fea-
tures of the environment to generate successive levels
of developmental advance.

The closest approximation to an operationalized
bioecological model in which directive beliefs function
as Person characteristics appears in a series of findings
arising from a doctoral dissertation by Tulkin (1973,
1977; Tulkin & Cohler, 1973; Tulkin & Kagan, 1972).
The investigator studied social class differences both in
the behaviors and the beliefs of mothers of 10-month-
old girls. The research was conducted in the home, em-
ploying both interviews and observations. Middle-class
mothers were distinguished from their working-class
counterparts not only by higher levels of reciprocal in-
teraction with their infants, but also in their views about
what a 10-month-old could do, and about their own abil-
ities to inf luence their baby’s development; the more ad-
vantaged mothers attributed greater potentials both to
their infants and themselves. In addition, the correla-
tions between maternal behavior and attitudes were sub-
stantially greater in middle-class than in lower-class
families. Several years later, Tulkin and a colleague
(Tulkin & Covitz, 1975) reassessed the same youngsters
after they had entered school. The children’s perfor-
mance on tests of mental ability and language skill
showed significant relationships to the prior measures of
reciprocal mother-infant interaction.

Perceptive readers may have detected a sleight of
hand in our analysis of Tulkin’s research when exam-
ined from the perspective of the bioecological model. In
that framework, we have been discussing characteristics
of the developing Person that inf luence proximal
processes and their outcomes. In Tulkin’s work, the de-
veloping Person is the infant. But the directive beliefs
we have been discussing are those of the mother. The
reason for the substitution is the following. Although, in
the line of work stimulated by Rotter and Bandura there
are many investigations of the relation between personal

812 The Bioecological Model of Human Development

beliefs and development, to our knowledge there have
been no studies of the effect of personal beliefs on the
proximal processes in which the developing person her-
self or himself becomes engaged. To provide an example,
we resorted to a substitution of roles.

The substitution also provides an opportunity to intro-
duce a corollary formulation, the evidence for which ap-
pears later in this and subsequent sections of this chapter:

In proximal processes involving interpersonal inter-
action, the personal characteristics that inf luence the
power of the process and its effects are the same for all
parties involved.

To return to the task at hand, we present a second
form of Person characteristic posited as affecting future
psychological growth—what we have called develop-
mental resources.

Resource Characteristics of the Person as
Shapers of Development

These are Person characteristics that in themselves in-
volve no selective disposition to action, but constitute
biopsychological liabilities and assets that inf luence the
capacity of the organism to engage effectively in proxi-
mal processes. In the first category are conditions that
limit or disrupt the functional integrity of the organism.
Some obvious examples include genetic defects, low
birthweight, physical handicaps, severe and persistent
illness, or damage to brain function through accident or
degenerative processes. By contrast, developmental as-
sets take the form of ability, knowledge, skill, and ex-
perience that, as they evolve over most of the life
course, extend the domains in which proximal processes
can do their constructive work—thereby becoming an-
other source of the progressively more complex patterns
of interaction constituting a defining property of proxi-
mal processes.

The similarity between the definitions for the two
types of developmental resources, and for the earlier
distinction between developmental outcomes ref lecting
dysfunction versus competence, derives from the fact
already noted that characteristics of the Person appear
on both sides of the bioecological equation. Develop-
mental outcomes at Time 1 indirectly inf luence develop-
mental outcomes at Time 2 through their effect on
proximal processes during the intervening period. The
difference, therefore, lies not in the concepts themselves
but in their place in the bioecological model.

A concrete example of a deficiency in developmen-
tal resources has already been documented in the
analysis of Drillien’s results depicted in Figure 14.1.
Proximal processes exerted their most powerful effect
on children growing up in the most disadvantaged envi-
ronment, but in that environment youngsters who at
birth were of normal weight benefited most. Weight at
birth does not imply a directed propensity to engage in
or refrain from a particular kind of behavior. What it
does represent is variation in the biological resources
available to engage in any activity requiring directed
activity or response over extended periods of time.
Thus, in the present instance, one plausible explanation
for the observed asymmetric pattern is that, among
families living in stressful environments, infants who
are physically healthy from birth are more able to en-
gage in reciprocal interaction than those who are bio-
logically impaired.

This interpretation is called into question, however,
by the corresponding results, shown in the same graph,
for infants raised under the most favorable socioeco-
nomic circumstances. Infants of normal birthweight
profited least from interaction with their mothers. How
might this paradox be resolved?

Even though the corresponding interaction term is
statistically significant, under normal circumstances
the preceding result would—and properly should—be
called into question as a post hoc finding. But, in the
present instance, that is not quite the case. To be sure,
there was no a priori hypothesis predicting the precise
pattern of the obtained results. The pattern is consis-
tent, however, with several possibilities envisioned for a
third Person attribute posited as inf luencing proximal
processes and their developmental effects. And for sci-
ence in the discovery mode, post hoc findings that are
theoretically relevant are not to be lightly dismissed.

Demand Characteristics of the Person
as Developmental Inf luences

The distinguishing feature of this last set of Person char-
acteristics affecting development is their capacity to in-
vite or discourage reactions from the social environment
that can disrupt or foster processes of psychological
growth: for example, a fussy versus a happy baby, attrac-
tive versus unattractive physical appearance, or hyperac-
tivity versus passivity. Half a century ago, Gordon
Allport (1937), borrowing a term originally introduced
by Mark A. May (1932), spoke of such characteristics as

The Role of Focus of Attention in Proximal Processes 813

constituting “personality” defined in terms of its “social
stimulus value.” Rephrasing this concept in terms of its
analog in contemporary theories of perception, we refer
to such Person qualities as demand characteristics.

A striking example of the developmental effect of
such a feature emerges as a major finding in one of the
follow-up studies of children of the Great Depression
carried out by Elder and his colleagues (Elder, Van
Nguyen, & Caspi, 1985). The investigators found that
economic hardship adversely inf luenced the psychoso-
cial well-being of girls ( but not boys) through its ten-
dency to increase the rejecting behavior of fathers. The
effects of rejection, however, varied inversely as a func-
tion of the daughter’s physical attractiveness. In the au-
thors’ words, “Attractive daughters were not likely to be
maltreated by their fathers, no matter how severe the
economic pressure. [The results] underscore the impor-
tance of viewing economic decline in relation to both the
child’s characteristics and parenting behavior ” (p. 361).
Here is a classic instance of the power of a PPCT model
in revealing the complex interactions between organism
and environment that drive the process of development.

The concept of demand characteristics also intro-
duces a new perspective for interpreting the contrasting
developmental effects of birthweight by social class
shown in Figure 14.1. As noted earlier, at the lowest
socioeconomic level it was the children of normal birth-
weight who benefited most from maternal responsive-
ness. But does that mean they were also the ones who got
the most attention from their mothers? Paradoxically,
the picture turns out to be just the reverse. Only 14% of
these lower-class mothers were judged to be responsive
to changes in their infants’ state or behavior, whereas
the percentage for mothers of low-birthweight babies
was more than twice as high (averaging 37%). In short,
lower-class mothers were responding mainly to those in-
fants who most needed their attention, albeit with a
lower return on their investment.

But what characteristics of these babies were captur-
ing the mothers’ attention? It appears likely that in this
instance, the mothers were responding mainly to their in-
fants’ expressions of distress—behavior less apt to occur
among those of normal birthweight. If we look at the cor-
responding data for families at the highest socioeconomic
level, we discover a rather different picture. Mothers are
more responsive to the healthiest infants than to those of
lowest birthweight, but as shown in Figure 14.1, they get
the least return for their pains. Once again a key question
becomes “ What is capturing the mother’s attention?” A

plausible answer for children of normal birthweight living
in the most favored circumstances is that their mothers
would be responding primarily not to manifestations of
problem behavior, but of growing competence.

TH E ROLE OF FOCUS OF ATTENTION IN
PROXIMAL PROCESSES

The preceding considerations, generated by a confronta-
tion of data with theory, call for more differentiated for-
mulations in the existing bioecological model. Here is
the first of two tentative responses to the call:

When a proximal process involves interaction with another
person, the power of the bioecological model is substan-
tially enhanced by including in the research design a mea-
sure of the other person’s focus of attention on the
particular aspects of the behavior of the subject that are
presumed, on theoretical and empirical grounds, to be most
closely related to the developmental outcome.

For Drillien’s study, the measure of proximal process
is the mother’s responsiveness, but we do not know to
what particular behaviors of her baby she was respond-
ing. As already suggested, the aspect most relevant for
reducing future problem behaviors might be expressions
of distress. If so, a more precise conceptual and opera-
tional definition of the proximal process in this study
would be the proportion of manifestations of distress
that were responded to by successful efforts to reduce
that distress.

However, even though in the Drillien study the moth-
ers’ focus of attention was not known, the extent of her
responsiveness was still a strong predictor of the out-
come. Even when the theoretical and operational re-
quirements of the bioecological model are not met in
full, the results can still contribute to understanding the
forces that shape human development.

A second, complementary tentative formulation de-
rives from the definition of proximal processes as bidi-
rectional. Stated succinctly, it posits that the preceding
formulation also holds in reverse:

When a proximal process involves interaction with another
person, the power of the bioecological model is substan-
tially enhanced by including in the research design a mea-
sure of the developing person’s focus of attention on the
particular aspects of the behavior of the other person that

814 The Bioecological Model of Human Development

are presumed, on theoretical and empirical grounds, to be
most closely related to the developmental outcome.10

PROXIMAL PROCESSES IN SOLO
ACTIVITIES WITH OBJECTS AND SYMBOLS

The foregoing considerations and complexities give
added importance to those proximal processes that do
not involve interpersonal interaction but instead focus on
progressively more complex reciprocal interaction with
objects and symbols. These are activities that can be car-
ried on in the absence of other persons, and therefore the
magnitude and effectiveness of the proximal process are
not inf luenced by another participant’s behaviors. One
would therefore expect that the person’s own disposition
and resources would play a far stronger role in affecting
the direction and power of the proximal process than in
the case of interpersonal interaction. Furthermore, such
solo activities significantly change the processes in-
volved, their outcomes, and the features of the environ-
ment that become most relevant. The contrast in all three
domains involves a focus on human relationships, on the
one hand, and tasks, on the other. To understand the de-
velopmental importance of this contrast requires a fuller
exposition of the features of the environment that inf lu-
ence proximal processes and their effects.

But before turning to this topic, we must give due
recognition to three other Person characteristics that
push us in the same direction. They are so pervasive in
affecting future development that their possible inf lu-
ence routinely needs to be considered in relation to the
particular phenomenon under investigation. These are
the familiar demographic factors of age, gender, and eth-
nicity. Another reason for this recommendation is that
all three of these factors, although based on differing
physical characteristics of the Person, also place that
person in a particular environmental niche that defines
his or her position and role in society. Recognition of
that ambiguity moves us to a change in focus from the
developmentally relevant characteristics of the Person to
their counterparts in the structure and substance of

environmental Contexts as they affect developmental
processes and outcomes.

TH E MICROSYSTEM MAGNIFIED:
ACTIVITIES, RELATIONSHIPS, AND ROLES

In addressing this topic, we return to the earliest formu-
lation of the ecological model. Today, as then, “ the
ecological environment is conceived as a set of nested
structures, each inside the other like a set of Russian
dolls” (Bronfenbrenner, 1979b, p. 3). The contemporary
definition of the innermost of these structures is similar,
but contains additional elements that link it to the “cen-
ter of gravity” of the bioecological paradigm:

A microsystem is a pattern of activities, social roles, and
interpersonal relations experienced by the developing per-
son in a given face-to-face setting with particular physi-
cal, social, and symbolic features that invite, permit , or
inhibit , engagement in sustained, progressively more com-
plex interaction with, and activity in, the immediate envi-
ronment. ( Bronfenbrenner, 1994, p. 1645)11

We begin with consideration of the first feature of the
environment introduced in the foregoing definition.

Ef fects of the Physical Environment on
Psychological Development

The pioneering work in this sphere has been done by
Theodore Wachs. In 1979, he published a seminal paper
in which he showed a consistent pattern of relationships
between certain features in the physical environment of
infants during the first 2 years of life and their cognitive
development over this same period. To permit examining
effects over time, data were grouped into successive 3-
month blocks. The results are reported in the form of
correlations between characteristics of the environment
at an earlier time and the developmental status of the in-
fants at a later time.

From the complex results of the study, we focus on
those physical features in the environment that were
most frequently and strongly associated with cognitive
functioning. These included a physically responsive en-

10 In terms of research design, both of the stated formulations
are best assessed through direct observation, but , given the
clarity and contrasting nature of the predicted relationship,
valid measures can be obtained for older children and adults
through well-designed interviews, and even for young chil-
dren from information provided by parents and other family
members.

11 The 1979 def inition reads as follows: “A microsystem is a
pattern of activities, roles, and interpersonal relationships
experienced by the developing person in a given setting with
particular physical and material characteristics.”

The Microsystem Magnif ied: Activities, Relationships, and Roles 815

vironment, presence of sheltered areas, “ The degree to
which the physical set-up of the home permits explo-
ration,” low level of noise and confusion, and “ the de-
gree of temporal regularity” (Wachs, 1979, p. 30).

Regrettably, few researchers have followed the ex-
citing scientific path that Wachs has been the first to
chart. Taken as a whole, his original and subsequent
work (Wachs, 1987a, 1987b, 1989, 1990, 1991; Wachs
& Chan, 1986) suggests two areas especially worthy of
further systematic investigation, in both conceptualiza-
tion and measurement. The first remains strictly in the
realm of the physical environment. The second raises
the issue of proximal processes as they relate to that
environment.

In the first domain, Wachs’s findings point to two
general aspects of the physical environment that can af-
fect the course of cognitive development—one for bet-
ter, the other for worse. On the constructive side are
objects and areas that invite manipulation and explo-
ration, whereas instability, lack of clear structure, and
unpredictability of events undermine the developmental
process. From an ecological perspective, the existence
of these countervailing forces in the physical environ-
ment leads to a new working hypothesis:

Not only do developmentally generative features of the
surroundings have greater impact in more stable settings,
but they also function as a buffer against the disruptive in-
f luences of disorganizing environments.

The second issue introduces an additional compo-
nent into the research design. As stipulated in Proposi-
tion I, proximal processes involve progressively more
complex interactions not only with persons but also
with objects and symbols. The question therefore again
arises as to what extent solitary activities involving ob-
jects and symbols—such as playing with toys, working
at hobbies, reading, or fantasy play—can also foster
psychological development? And to what degree does
involvement in both objects and symbols produce syner-
gistic developmental effects in each domain? The an-
swers to these questions are as yet unknown but are
readily discoverable through the use of appropriate de-
signs that differentiate between measures of process
and of environmental structure.

However, the most promising terra incognita for re-
search on the role of the physical environment in human
development may well lie beyond the realm of childhood
in the world of adults. A preview of this promise appears

in the successive publications of the sociologist Melvin
Kohn and his colleagues (for an integrative summary,
see Kohn & Slomczynski, 1990) demonstrating the pow-
erful effect of work environments on intellectual devel-
opment in adulthood. Of particular importance in this
regard turns out to be the complexity of the task that a
given job entails.

At the conclusion of the preceding section, we called
attention to a contrast that cuts across all four domains
of Process, Person, Context, and Developmental Out-
come. The contrast in all four domains involves a pri-
mary focus on relationships versus tasks. The findings
of both Wachs and Kohn fall mainly in the latter cate-
gory, but Drillien’s data on mother-infant interaction
and infants’ problem behavior in lower-class families
fall mainly in the former (i.e., an increase in maternal
responsiveness functions as a buffer against problems in
this sphere of emotional and behavioral control).

But that is not the only effect of rising levels of prox-
imal process.

The Mother-Infant Dyad as a Context
of Development

A substantial body of research indicates that such
processes also foster the development of a strong emo-
tional attachment between mother and child, which
increases the quality of future interaction between the
two parties (Ainsworth, Blehar, Waters, & Wall, 1978;
Bowlby, 1969, 1973). In addition, the more recent work
in this sphere strongly suggests that, as a result of con-
tinuing reciprocity in the context of a close relationship,
the infant begins to develop a definition of self that mir-
rors the form and content conveyed through the evolving
patterns of interchange between mother and child
(Sroufe, 1990). Thus, proximal processes become the
measurable mechanisms for bringing about what in an
earlier era of developmental theory and research was
called internalization.12 Moreover, this sequential pro-
cess does double duty. Though operating primarily on
the relationship side, it also furthers task performance.

According to attachment theory, the emotionally
loaded patterns of interchange processes between the
infant and the primary caregiver become internalized
in the form of “internal working models” (Bowlby,

12 A resurgence of theoretical and research interest in this
sphere has been stimulated by the elegant studies of Kochan-
ska and her colleagues.

816 The Bioecological Model of Human Development

1969, 1973). Such working models are representations
of the infant in relation to others and become the basis
for the development of the self (Sroufe, 1990). Through
interactions between the infant and the primary care-
giver, the infant develops expectations of the care-
giver’s behavior and complementary beliefs about him-
or herself. For example, an infant who has experienced
a history of contingent responsiveness from a primary
caregiver will develop a model of that caregiver as
available, and expect such behavior. That child will
also develop a complementary sense of self that he or
she is worthy of responsive care. On the other hand, an
infant who has experienced unresponsive care will de-
velop a very different model of the relationship, ex-
pecting the caregiver to be unavailable. Such an infant
is expected to develop a sense of self as unworthy of re-
sponsive care.

More generally, these internalized working models
are seen as providing a framework for future interac-
tions, resulting in a repetition of the early attachment
relationship (Bowlby, 1973; Sroufe, 1990). The child
seeks, responds, and interprets events based on the
model that he or she has developed during infancy, and
that model is adapted based on new experiences with the
environment. A child who has developed a secure at-
tachment relationship is likely to expect positive inter-
actions with teachers, and thus elicit responsive care
reminiscent of his or her caregiver’s behavior. An inse-
cure child, expecting rejection, will approach relation-
ships with increased hostility, ultimately resulting in
further experiences with rejection.

Support for these theoretical expectations comes
from a number of studies. For example, the quality of
the child’s early attachment relationship with the
mother has been found to affect the child’s later func-
tioning in social interactions with teachers and peers.
Thus, early proximal processes produce proximal
processes throughout development. Children judged as
securely attached in infancy have been shown to ap-
proach unfamiliar peers and adults more positively
and with greater acceptance ( Booth, Rose-Krasnor,
McKinnon, & Rubin, 1994; Main & Weston, 1981;
Pastor, 1981). Furthermore, they have more positive
relationships with peers and teachers in preschool
(Sroufe, Fox, & Pancake, 1983; Turner, 1991). Be-
cause secure children have developed a positive inter-
nal working model in the context of a secure
attachment relationship with a primary caregiver,

these children expect and elicit positive interactions
with other social partners.

This body of attachment theory and research has im-
portant implications for the bioecological model. Its rel-
evance is most succinctly conveyed in operational
terms, by assessing quality of attachment in different
positions in the research design; for example, as an out-
come at Time 2 of proximal processes at Time 1, or, al-
ternatively, in the form of strong versus weak contextual
dyads at Time 1 moderating the power of a proximal pro-
cess to inf luence developmental outcomes at Time 2. The
latter design fits a long-standing proposition derived
from the bioecological model, which reads as follows:

In order to develop—intellectually, emotionally, socially,
and morally—a child requires, for all of them, the same
thing: participation in progressively more complex recip-
rocal activity, on a regular basis over extended periods of
time with one or more other persons with whom the child
develops a strong, mutual, irrational attachment ,13 and
who are committed to that child’s development , preferably
for life. ( Bronfenbrenner, 1989c, p. 5)

A second proposition goes a step further:

The establishment and maintenance of patterns of progres-
sively more complex interaction and emotional attachment
between caregiver and child depend in substantial degree
on the availability and active involvement of another adult
who assists, encourages, spells off, gives status to, and ex-
presses admiration and affection for the person caring for
and engaging in joint activity with the child. ( Bronfen-
brenner, 1989c, p. 11)

Taken together, the foregoing propositions present an
important qualifier to the general finding that children
growing up in single-parent families are at greater de-
velopmental risk than those in two-parent structures.
What counts most is the quality of the relationships and
activities that take place in the family, and situations
can occur in which, from this perspective, quality over-
rides quantity (Hetherington & Clingempeel, 1992).

Both propositions take on added importance because
their relevance may extend beyond parental ties to close
relationships with other caregivers, relatives, peers,
teachers, mentors, coworkers, and supervisors. The
propositions may also apply beyond childhood and ado-

13 What is meant by the term “ irrational attachment ”? One
answer : This is the f irst child you try to save in a f ire.

Beyond the Microsystem 817

lescence to relationships in adulthood and old age. So
far as we have been able to discover, these possibilities
still await systematic investigation in correspondingly
appropriate research designs.

BEYOND TH E MICROSYSTEM

It is a basic premise of ecological systems theory that
development is a function of forces emanating from
multiple settings and from the relations among these
settings. How can such multiple forces and their interre-
lations be conceptualized, and what kinds of research
designs can be employed to measure their combined ef-
fects? The first stage in such an expanded model of the
environment involves what in ecological systems theory
is called a mesosystem, defined as comprising the rela-
tionships existing between two or more settings; in
short, it is a system of two or more microsystems.
Mesosystems and their operationalization in a research
design are best conveyed through a concrete example.

Steinberg, Darling, and Fletcher (1995) reported on
what they described as “an ecological journey,” which
was the consequence of a deliberate decision made at
the outset of their research. The initial focus of inves-
tigation was on the impact of authoritative parenting
on adolescents’ academic achievement. They had at
their disposal a range of data collected from a large
multiethnic, multiclass sample encompassing several
family structures. Under these circumstances, they
concluded:

[I]t made no sense at all to control for ethnicity, social
class, or household composition in an attempt to isolate
“ pure” process. No process occurs outside of a context.
And if we want to understand context , we need to take it
into account , not pretend to control it away. (Steinberg
et al., 1995, p. 424)

No sooner had the investigators embarked on this
unconventional course than they encountered some un-
expected f indings. The f irst of these occurred not in
the realm of environmental context but of developmen-
tal outcome. When they analyzed adolescents’ school
performance, they found that , in contrast to youth
from European family backgrounds, Hispanic,
African, or Asian American youth did not benef it from
authoritative parenting. A f irst clue to this puzzle
emerged when the investigators identif ied the values

held by the different “ peer crowds” (e.g., “ jocks,
brains, nerds, preppies, or druggies”) in the nine high
schools included in their sample. Their subsequent
analysis revealed that “European-American young-
sters from authoritative homes are more likely to be-
long to peer crowds that encourage academic
achievement ” (Steinberg et al., 1995, p. 445).

On the basis of these and related findings, Steinberg
et al. (1995) formulated the following, new working
hypothesis:

There is a strong but indirect path between parenting prac-
tices and adolescent peer group aff iliations . . . by foster-
ing certain traits in their children, parents direct a child
toward a particular peer group. Thus to the extent that par-
ents can inf luence characteristics by which adolescents
are associated by peers with a crowd, parents can “con-
trol” the type of peer group inf luences to which their child
is exposed. . . . In essence, parents have a direct and pri-
mary impact on adolescent behavior patterns—prosocial
as well as antisocial. Peer groups serve primarily to rein-
force established behavior patterns or dispositions.
( pp. 446 – 447 )

But when the investigators put their new hypothesis
to the test, they were confronted by yet another unex-
pected result:

When we attempted to apply this model to youngsters
from minority backgrounds, we were in for a shock. We
found that among Black and Asian students, there was no
relation between parenting practices and peer crowd mem-
bership. ( p 447 )

Once again, the researchers’ “multiple context model”
paved the way to solving the puzzle:

Why was there not signif icant relation between parenting
and peer group selection among minority youth? The an-
swer, we discovered, is that models of peer group selection
that assume an open system, in which adolescents can se-
lect into any number of groups as easily as ordering food
off a restaurant menu, fail to take into account the tremen-
dous level of ethnic segregation that characterizes the so-
cial structure of most ethnically mixed high schools in the
United States. ( pp. 447– 448)

The authors’ findings with respect to specific minor-
ity groups are of considerable interest:

818 The Bioecological Model of Human Development

Although [African American] parents score highest on our
measure of parental involvement in schooling, [Black ado-
lescents] f ind it much more diff icult to join a peer group
that encourages the same goal. ( p. 449)

By contrast:

More often then not , Asian American students have no
choice but to belong to a peer group that encourages and
rewards academic excellence. . . . Asian Americans report
the highest level of peer support for academic achieve-
ment. Interestingly, and in contrast to popular belief,
[their] parents are the least involved in their youngsters’
schooling. ( p. 448)

The Expanding Ecological Universe

As if disappointed at not being confronted with yet an-
other unexpected finding, Steinberg and his colleagues
moved on to extend the ecological model to its next higher
systems level—that of the exosystem. The formal defini-
tion of this environmental structure reads as follows:

The exosystem comprises the linkages and processes tak-
ing place between two or more settings, at least one of
which does not contain the developing person, but in
which events occur that indirectly inf luence processes
within the immediate setting in which the developing per-
son lives. ( Bronfenbrenner, 1993, p. 24)

The particular exosystem that Steinberg et al. (1995)
undertook to investigate was “ the network of families
that develops through the child’s peer relationships,”
more specifically, “ the parenting practices of their
peers’ parents” (p. 450). The investigators’ analyses led
to a series of interrelated findings as shown in these
two examples:

Adolescents whose friends’ parents are authoritative earn
higher grades in school, spend more time on home-
work . . . have more positive perceptions of their academic
competence, and report lower levels of delinquency and
substance use.

Adolescents whose parents are already more authorita-
tive appear to benef it more from membership in a peer
network with other authoritatively reared youngsters than
do adolescents in similar networks, but from less authori-
tative homes. It appears that adolescents need certain
“ home advantages” in order to be able to take advantage of
the social capital in their social networks. (Steinberg
et al., 1995, pp. 452– 453)

Presumably, even an ecological model can only be
taken so far, but Steinberg and his colleagues appear to
be trying to push it to its limits—their next analysis
moves from the parental network of the adolescent’s
peers to the neighborhood’s level of social integration.
The measure of integration was based on a series of
questions about parents’ contact with their children’s
friends, participation in community and social activi-
ties, and ties to other families in the neighborhood. An
analysis of the data revealed a modest effect of neigh-
borhood integration on ado-lescent development. How-
ever, this finding was qualified in an important way that
refocused attention on the key role played by family
processes. In the author’s words:

When we reran these analyses separately in neighbor-
hoods characterized by a high proportion of effective ver-
sus noneffective parents, we f ind that . . . social
integration only benef its adolescents whose families live
in neighborhoods characterized by good parenting. Social
integration into a neighborhood characterized by a high
proportion of bad parents has a harmful effect on adoles-
cents’ school performance and behavior. (Steinberg et al.,
1995, p. 457 )

A subsequent analysis revealed a second, equally
critical but not surprising qualifier: “Living in a neigh-
borhood characterized by a high degree of social inte-
gration is only beneficial to an individual
adolescent if the child’s family is also socially inte-
grated” (p. 457).

Steinberg et al.’s final analysis adds psychological
substance to social structure. By aggregating informa-
tion on parenting practices and attitudes in a neighbor-
hood, he and his associates were able to calculate a
measure of the degree of consensus among parents in a
given neighborhood. Once again, the principal finding
emerging from the analysis was conditioned by a
psychological reality:

High neighborhood consensus augments the association
between parenting and adolescent outcomes only when
the consensus is around good parenting. . . . In other
words, it is what parents agree about , not merely whether
they agree, that makes the difference. (Steinberg et al.,
1995, p. 458)

In this particular study, the investigators did not ex-
amine the extent to which the biopsychological charac-
teristics of adolescents, or of their parents, inf luenced

Beyond the Microsystem 819

developmental processes and outcomes. Today, a grow-
ing body of researchers (e.g., Plomin, Reiss, Hethering-
ton, & Howe, 1994) claims strong evidence for the view
that individual and group differences in a wide range of
developmental outcomes are mainly driven by differ-
ences in genetic endowment (“Ability Testing,” 1992;
Plomin, 1993; Plomin & Bergeman, 1991; Plomin &
McClearn, 1993; Scarr, 1992). This claim is called into
question, however, by alternative explanations and evi-
dence based on the bioecological model (see also
Lerner, 1995, 2002, 2004a).

Nature-Nurture Reconceptualized:
A Bioecological Interpretation

The theoretical argument is set forth in a series of hy-
potheses, each accompanied by a corresponding re-
search design (Bronfenbrenner & Ceci, 1994b).

Hypothesis 1: Proximal processes raise levels of ef-
fective developmental functioning, and thereby in-
crease the proportion of individual differences
attributable to actualized genetic potential for such
outcomes. This means that heritability ( h2) will be
higher when proximal processes are strong and lower
when such processes are weak.

Hypothesis 2: Proximal processes actualize genetic
potentials both for enhancing functional competence
and for reducing degrees of dysfunction. Opera-
tionally, this means that as the level of proximal pro-
cess is increased, indexes of competence will rise,
those of dysfunction will fall, and the value of h2 will
become greater in both instances.

1. The power of proximal processes to actualize ge-
netic potentials for developmental competence (as
assessed by an increase in h2) will be greater in
advantaged and stable environments than in those
that are disadvantaged and disorganized.

2. The power of proximal processes to buffer genetic
potentials for developmental dysfunction will be
greater in disadvantaged and disorganized environ-
ments than in those that are advantaged and stable.

Hypothesis 3. If persons are exposed over extended
periods of time to settings that provide developmental
resources and encourage engagement in proximal
processes to a degree not experienced in the other
settings in their lives, then the power of proximal
processes to actualize genetic potentials for develop-

14 Sundet ( personal communication, March 17, 1993) re-
ported that , in response to a preliminary version of the article
by Bronfenbrenner and Ceci (1994), he and his colleagues un-
dertook a preliminary analysis that yielded the following re-
sults: “For twins with mothers having the least education, the
correlation between identical twins is .80, whereas the corre-
lation for fraternal twins is .47. For the twins having mothers
with more education, these correlations are .82 and .39, re-
spectively. As you will see, this yields a heritability estimate
of .66 for the f irst group, whereas it is .86 for the second
group. If I understand your [Hypothesis 2] correctly, this is in
accordance with your predictions. However, the difference
between the two DZ [dizygotic] correlations does not seem to
reach statistical signif icance, although it is quite near.”

mental competence will be greater for those living in
more disadvantaged and disorganized environments.

To test the preceding hypotheses, Bronfenbrenner and
Ceci (1994b) reviewed literature on genetic inheritance:

We have been able to f ind no studies of genetic inheritance
in contrasting environments that also contained data on
proximal processes and hence would permit a direct test
of the previous hypotheses. Hence, most of the available
evidence is indirect.

An indirect test can be carried out only when estimates
of heritability are reported for the same developmental
outcome in different environments. It is fortunate that
there are several studies that meet this criterion. To begin
with, both Scarr-Salapatek (1971) and Fischbein (1980)
found support for the prediction that values of h2 for IQ
would be greater in higher than in lower social class
groups. Subsequently, a group of Nor wegian investigators
(Sundet , Tambs, Magnus, & Berg, 1988) undertook to
clarify a series of earlier f indings regarding secular trends
over recent decades in heritability for measures of cogni-
tive functioning. Using IQ scores as outcome data , the in-
vestigators found some support for results of a previous
study of educational attainment ( Heath et al., 1985) that
had shown an increase in h2 for twins born after 1940. The
trend for their mental test data , however, was considerably
weaker. The authors offered the following interpretation
of the observed similarity and contrast:

This is probably due at least partly to the fact that the
Nor wegian government in the postwar period has of-
fered loans to young people seeking education, thus en-
abling youngsters with poor parents to attend higher
education. Such factors, together with a more positive
attitude toward education among poor people, would
tend to decrease the effect of familial environments and
maximize genetic potential. (Sundet et al., 1988, p. 58)14

820 The Bioecological Model of Human Development

There are also a number of investigations that permit
an indirect test of the hypothesized reverse pattern when
the outcome is one of developmental dysfunction. For ex-
ample, Jenkins and Smith (1990) found that the positive
effect of a good mother-child relationship on children’s
problem behavior was stronger in a troubled marriage than
in a harmonious one. More generally, in a recent review,
Rutter and Rutter (1992) concluded that the impact of pro-
tective factors in buffering developmental disorders is
greater in “circumstances of risk.” ( p. 56 )

This concludes Process, Person, and Context as
shapers of development, it is time to turn to Time.

TIME IN TH E BIOECOLOGICAL MODEL:
MICRO-, MESO-, AND
MACROCHRONOLOGICAL SYSTEMS

Time, a defining property of the bioecological paradigm,
appears more than once in the model’s multidimensional
structure. Indeed, its first appearance, in the second
sentence of Proposition I, may have well gone unnoticed.
Following the definition of proximal processes as in-
volving progressively more complex reciprocal inter-
action, the Proposition stipulates that to be effective,
the interaction must occur on a fairly regular basis.

Why this proviso? A first indication appears in the
findings from Wachs’s research (1979) on the features
of the environment most frequently and strongly associ-
ated with individual differences in cognitive compe-
tence. Prominent among them were a physically
responsive environment, presence of sheltered areas, in-
stability and unpredictability of events, the “degree to
which the physical set-up of the home permits explo-
ration,” low level of noise and confusion, and “ the de-
gree of temporal regularity” (p. 30). As noted earlier, it
follows from such findings that proximal processes can-
not function effectively in environments that are unsta-
ble and unpredictable across space and time.

It also follows that the cumulative effects at this
mesosystem level are likely to jeopardize the course of
human development. One reason for expecting such an
escalating effect is that, at this next higher level of en-
vironmental structure, similarly disruptive characteris-
tics of interconnected microsystems tend to reinforce
each other.

The most informative research evidence bearing on
this issue comes from a longitudinal study conducted by
the Finnish psychologist, Lea Pulkkinen (1983). Begin-
ning when participating children were 8 years of age, she

investigated the effect of environmental stability and
change on the development of children through adoles-
cence and young adulthood, The “steadiness” versus “ un-
steadiness” of family living conditions was measured by
the frequency of such events as the following: the number
of family moves, changes in day care or school arrange-
ments, extent of family absence, incidence of divorce and
remarriage, and altered conditions of maternal employ-
ment. Greater instability in the family environment was
associated with greater submissiveness, aggressiveness,
anxiety, and social problems among children in later
childhood and adolescence, leading to higher risks of vio-
lence and criminal behavior in early adulthood (Pulkki-
nen, 1983; Pulkkinen & Saastamoinen, 1986). Moreover,
the factor of stability of family living conditions ap-
peared to be a stronger determinant of subsequent devel-
opment than was the family’s socioeconomic status.

Analogous findings for the contemporary U.S. scene
were obtained by Moorehouse (1986) in a study of how
stability versus change over time in the mother’s work
status during the child’s preschool years affected pat-
terns of mother-child communication, and how these
patterns in turn inf luenced the child’s achievement and
social behavior in the 1st year of school. A key analysis
involved a comparison between mothers who had main-
tained the same employment status over the period of
the study, and those who had changed in either direc-
tion: that is, to working more hours, fewer hours, or none
at all. The results revealed that significant effects of
work status were pronounced only in the group that had
changed their working status. Although the disruptive
impact was greatest among those mothers who had
moved into full-time employment, it was still present
even for those who had reduced their working hours or
had left the labor force. Moorehouse concluded that “in-
stability, on the whole, is associated with less favorable
school outcomes than stability” (p. 103).

In the framework of the discovery mode, we are once
again at a point where a series of findings from different
studies suggests yet another tentative formulation. The
corollary follows:

The degree of stability, consistency, and predictability
over time in any element of the systems constituting the
ecology of human development is critical for the effective
operation of the system in question. Extremes either of
disorganization or rigidity in structure or function repre-
sent danger signs for potential psychological growth, with
some intermediate degree of system f lexibility constitut-
ing the optimal condition for human development. In re-

Time in the Bioecological Model: Micro-, Meso-, and Macrochronological Systems 821

15 For an earlier, but more comprehensive account , see Elder’s
Chapter 16, this Handbook, this volume.

search design, this proposition points to the importance of
assessing the degree of stability versus instability, with
respect to characteristics of Process, Person, and Context ,
at each level of the ecological system.

This formulation also applies at the macrolevel to the
dimension of Time, both during the individual’s life
course, and through the historical period in which the
person has lived (see Proposition II ). It was this observa-
tion that gave rise to the first systematic formulation of
what was to become the ecological model of human devel-
opment. The formulation appeared almost 4 decades ago
in an article entitled “Socialization and Social Class
through Time and Space” (Bronfenbrenner, 1958). In that
article, Bronfenbrenner reanalyzed what appeared to be
contradictory findings on social class differences in pat-
terns and outcomes of child rearing. The analysis reveals
that when the obtained results were reorganized by the
years in which the data were collected, the contradictory
findings disappeared. Instead, there was a systematic
gradual change over the period just after World War II
until the late 1950s, with middle-class parents moving
away from originally more authoritarian patterns toward
greater permissiveness and lower-class families going in
the opposite direction. Changes in patterns of child rear-
ing over historical time and their effects on development
have been recurring themes in Bronfenbrenner’s work be-
ginning in the late 1950s (1958) and continuing up to the
present (Bronfenbrenner, 1970, 1975, 1990, 1994; Bron-
fenbrenner & Crouter 1982; Bronfenbrenner et al., 1996);
but in terms of theoretical and empirical contributions
this work pales in comparison with that of Elder, begin-
ning with his classic study, Children of the Great Depres-
sion (Elder, 1974; see also Elder & Shanahan, Chapter
12, this Handbook, this volume).

As Bronfenbrenner has noted, Elder’s work on life-
course development played a significant role in the formu-
lation of the original ecological model (Bronfenbrenner,
1979a, see especially pp. 266–285 and 273–285), and has
exerted even greater inf luence on the model’s subsequent
evolution in this same domain (Bronfenbrenner, 1986a,
1986b, 1989, 1993, 1995).

Because Elder’s contributions deservedly receive ex-
tended coverage in Chapter 12, this Handbook, this vol-
ume, we confine ourselves to the four defining principles
of life-course theory as presented in a recent formulation
(Elder, 1998),15 along with implications for correspon-

ding research designs, and examples of relevant research
findings.

The first principle is that of historical time and place,
defined by Elder as follows: The life course of individu-
als is embedded in and shaped by the historical times and
events they experience over their life time.

History is exploited as an experiment of nature.
The corresponding research design compares groups
similar in other respects who have been exposed, ver-
sus not exposed, to a particular historical event; for
example, Elder’s studies of the Great Depression
( Elder, 1974; also see Elder, 1998; Elder & Shanahan,
Chapter 12, this Handbook, this volume); military
service and actual combat in World War II and Korea
( Elder, 1986; Elder, Shanahan, & Clipp, 1994);
the Iowa farm crisis (Conger & Elder, 1994; Elder,
King, & Conger, 1996 ); urban inequality ( Elder,
Eccles, Ardelt , & Lord, 1995); and, Elder’s most re-
cent work, research on youth sent to the countryside
during China’s cultural revolution ( Elder, Wu, &
Jihui, 1993).

The second principle, called timing in lives, states that
the developmental impact of a succession of life transi-
tions or events is contingent on when they occur in a per-
son’s life.

Here an appropriate research design is one that com-
pares early versus late arrivals at a particular transition
with respect to their subsequent life course. For exam-
ple, Elder et al. (1994) reanalyzed follow-up data on
subjects from Terman’s 1925 classic Genetic Studies of
Genius (all subjects with very high IQs) and were able
to show marked differences in subsequent adult develop-
ment depending on early versus late entrance into mili-
tary service during wartime. Some of the costs of late
entry include:

• A higher risk of divorce and separation

• A work life of disappointment and loss of lifetime income

• An accelerated decline of physical health, most no-
tably after the age of 50

On the opposite side:

• For many men, and especially those who entered at
an early age, military service was a recasting expe-
rience. It provided a bridge to greater opportunity
and an impetus for developmental growth up to the
middle years.

822 The Bioecological Model of Human Development

One is reminded of Brutus’s fateful choice in re-
sponse to Cassius’s urgings:

There is a tide in the affairs of men
Which, taken at the f lood, leads on to fortune;
Omitted, all the voyage of their life
Is bound in shallows and in miseries.

—Shakespeare, Julius Caesar ( IV. iii. 218–221)

The third principle, linked lives, asserts that lives
are lived interdependently and social and historical in-
f luences are expressed through this network of shared
relationships.

The basic research design corresponding to this
principle involves examining the differential impact
of historical events and role transitions on different
members of the same family experiencing these
same events and transitions. In a study of mother-
daughter dyads in the broader historical context of
the societal changes in gender roles that have taken
place since World War II, Moen and Erickson (1995)
offered the following concluding comment , on the
basis of their statistical analysis of data across two
generations:

Conventional mothers embracing traditional gender roles
may f ind themselves with daughters who are in the van-
guard of the women’s movement. Some mothers may even
push their daughters to achieve what was impossible for
themselves. The fact that mothers and daughters experi-
ence historical events and social changes from different
vantage points means that their lives are differentially
touched by them and that their perspectives may well di-
verge. ( p. 180)

Environmental changes across historical time can
produce signif icant developmental changes in either
direction. On the one hand, they can disrupt the timing
and duration of normative transitions during the life
course, thus interrupting the sequence of learning ex-
periences that are essential for meeting societal ex-
pectations as one gets older. On the other hand, they
can offer to the person new, at once more stable
and more challenging opportunities that enhance psy-
chological growth or even reverse a previously down-
ward course (e.g., Elder’s 1974 studies of effects
of military enlistment on young men from poverty
backgrounds).

FROM RESEARCH TO REALITY

The fourth and last of Elder’s principles of life course
development he calls human agency. It states that “indi-
viduals construct their own life course through choices
and actions they take within the opportunities and con-
straints of history and social circumstances.” A striking
example is his finding that the young men most likely to
volunteer early for service in World War II were often
those who came from the most deprived circumstances,
but then benefited the most from the opportunities of
training and experience that the military provided. Nev-
ertheless, he cautions that “Not even great talent and in-
dustry can ensure life success over adversity without
opportunities” (Elder, 1997).

Finally, to Elder’s four principles, we add a fifth,
which in effect reverses the direction of his very first
principle regarding the importance of historical changes
in shaping the course of human development. Simply
stated, the fifth principle asserts that changes over time
in the four defining properties of the bioecological
model are not only products but also producers of histor-
ical change. To spell out the argument and evidence on
which the principle is based: Periodically, since the late
1950s, Bronfenbrenner, together with colleagues, has
been publishing articles documenting changes over time
in three domains: child-rearing practices, the relation of
these practices to child outcomes, and in family demo-
graphics reported annually in the U.S. Census and other
government publications.

One report of these analyses appears in a volume en-
titled: The State of Americans: This Generation and the
Next (Bronfenbrenner et al., 1996). The book consists of
almost 300 pages and 150 graphs, but, for present pur-
poses, the principal findings can be summarized in 10
points shown in Table 14.1. Considered as a whole, the
findings constitute the basis for our proposed addition
to Elder’s four principles.

To illustrate, although proximal processes function
as the engines of development, the energy that drives
them comes from deeper sources that take us back to
the experiential world of Proposition I (Bronfenbrenner
et al., 1996; Bronfenbrenner & Evans, 2000; Bronfen-
brenner & Morris, 1998). Both subjective and objective
forces exert an especially strong inf luence on develop-
ment during the formative years (from early infancy to
young adulthood). A substantial body of research over
the past century indicates that, 2 or 3 decades ago,

From Research to Reality 823

TABLE 14.1 Summary of Selected Findings

1. Annual surveys over the past two decades reveal growing
cynicism and disillusionment among American youth, ref lected
in a loss of faith in others, in their government , in the basic
institutions of their society, and in themselves.

2. In the United States far greater percentages of youth and
women are victims of homicide, with rates more than 10 times
as high as those for any other developed country.

3. The young are not only likely to be the victims of murder, they
are also more likely to commit it. Youth and young adults (ages
18–25) now account for the majority of those arrested for
homicide.

4. The percentage of Americans in prison is four times higher
than in other developed countries, and the number is rising
rapidly.

5. Despite recent gains made by youth from Black families.
American high school students are still far behind those from
other developed countries in academic achievement. This
includes the top 10% of students in each nation. The trend
already threatens our productivity and capacity to compete
economically in the future.

6. The United States stands in f irst place in the percentage of
children growing up in single-parent families, which now
includes over a quarter of all America’s children under 6 years
of age.

7. Families with children under 6, particularly single-parent
mothers, are those who most seek—and desperately need—
a job. But they also have the highest unemployment rates. The
proportion of Black mothers working full time is much higher
than for white mothers ( in 1994, 76% vs. 29%).

8. The percentage of U.S. children living in poverty today is
twice as high as that for any other developed nation.

9. Among developed nations, the incomes of rich versus poor
families are farthest apart in the United States. We are rapidly
becoming a two-class society.

10. Two-thirds of children in poverty live in families with working
adult. Less than one-third of poor families with a young child
rely solely on welfare.

We are indebted to our colleagues who, as coauthors of chapters of
the volume The State of Americans: This Generation and the Next,
provided the f indings summarized in Table 14.1. Besides ourselves,
they include the following: Steven J. Ceci, Helen Hembrooke, Peter
McClelland, Phyllis Moen, Elaine Wethington, and Tara L. White.
Source: From The State of Americans: This Generation and the Next,
by U. Bronfenbrenner, P. McClelland, E. Wethington, P. Moen, and
S. J. Ceci, 1996, New York: Free Press.

these forces lay mainly in the family, with parents act-
ing as the principal caregivers and sources of emo-
tional support for their children, and with other adult
family members living in the home being next in line.
To a lesser extent, other relatives, family friends, and
neighbors also functioned in this role.

However, there has been a marked change in this pat-
tern over the past 4 decades. Parents, and other adult
family members as well, have been spending increasing
amounts of time commuting to and working at full-time

jobs (in which overtime is increasingly required or ex-
pected). The nature of this trend and its relevance
for human development are conveyed in the idea that
to develop—intellectually, emotionally, socially, and
morally—a child requires, for all of these, the same
thing: participation in progressively more complex ac-
tivities, on a regular basis over an extended period of
time in the child’s life, with one or more persons with
whom the child develops a strong, mutual emotional
attachment, and who are committed to the child’s well-
being and development, preferably for life (Bronfen-
brenner & Evans, 2000; Bronfenbrenner & Morris,
1998; also see Lerner, 2004b). The establishment of a
strong mutual emotional attachment leads to internal-
ization of the parent’s activities and expressed feelings
of affection. Such mutual ties motivate the child’s inter-
est and engagement in related activities in the immediate
physical, social, and—in due course—symbolic environ-
ment that invite exploration, manipulation, elaboration,
and imagination.

The establishment and maintenance of patterns of
progressively more complex interaction and emotional
attachment between parent and child depend, to a sub-
stantial degree, on the availability and involvement of
another adult, a third party, who assists, encourages,
spells off, gives status to, and expresses admiration and
affection for the person caring for and engaging in joint
activity with the child. It also helps, but is not absolutely
essential, that the third party be of the opposite sex from
that of the other person caring for the child, because this
is likely to expose and involve the child in a greater vari-
ety of developmentally instigative activities and experi-
ences (Bronfenbrenner et al., 1996). Where this is an
attachment to two or more parent figures, each can serve
as a third party to the other.

The research evidence for this idea comes mainly by
default. It was produced by demographic data document-
ing a rapid rise in the proportion of single-parent house-
holds. The trend began in the 1980s, and then continued
at an even faster rate through most of the 1990s. The
overwhelming majority of such homes were those in
which the father was absent and the mother bore pri-
mary responsibility for the upbringing of the children.

A large number of investigations of developmental
processes and outcomes in families of this kind have
since been conducted across a range of cultural and so-
cial class groups. The findings lead to two complemen-
tary conclusions:

824 The Bioecological Model of Human Development

1. Even in families living in favorable socioeconomic
circumstances, children of single-parent mothers, or
of fathers, for whom no other person is acting reli-
ably in a third party role are at greater risk for expe-
riencing one or more of the following developmental
problems: hyperactivity or withdrawal, lack of atten-
tiveness, difficulty in deferring gratification, poor
academic achievement, school misbehavior, and fre-
quent absenteeism.

2. At a more serious level, there is the so-called teenage
syndrome of behaviors that tend to be associated to-
gether: dropping out of school; involvement in so-
cially alienated or destructive peer groups; smoking,
drinking, frequent sexual experience: adolescent
pregnancy; a cynical attitude toward work; and in the
more extreme cases—drugs, suicide, vandalism, vio-
lence, and criminal acts. Most of these effects are
more pronounced for boys than for girls (Bronfen-
brenner et al., 1996).

Not all single-parent families, however, exhibited
these disturbed relationships and their disruptive ef-
fects on children’s development. Systematic studies of
the exceptions have identified what may be described as
a general immunizing factor. For example, children of
single parents were less likely to experience develop-
mental problems especially in families in which the
mother (or father) received strong support from other
adults living in the home. Also helpful were nearby rela-
tives, friends, neighbors, members of religious groups,
and, when available, staff members of family support
and child care programs. What mattered most was not
only the attention given to the child—important as this
was—but also the assistance provided to the single par-
ent or by others serving in the supportive roles previ-
ously noted. It would seem that, in the family dance, it
takes three to tango.

But dancing is not the whole story. By the 1980s, the-
ory and research in the ecology of human development
had documented an accelerating trend toward greater
permissiveness in styles of child rearing in U.S. fami-
lies. At the same time, successive scientific investiga-
tions had revealed progressively greater developmental
advantage for strategies that placed increased emphasis
on parental discipline and demand. The interpretation
that emerged from analyses of the available data sug-
gested that widespread application of these research
findings would serve as an effective response to the de-

16 Once again we emphasize that the relationships and activi-
ties in which parent and child are involved can override the
inf luence of purely demographic factors such as mother’s age
and family structure ( p. 1015).

velopmentally disruptive changes taking place in con-
temporary society.

At a more general level, the research findings reveal
growing chaos in the lives of families, in child care set-
tings, schools, peer groups, youth programs, neighbor-
hoods, workplaces, and other everyday environments in
which human beings live their lives. Such chaos inter-
rupts and undermines the formation and stability of re-
lationships and activities that are essential for
psychological growth. Moreover, many of the conditions
leading to that chaos are the often unforeseen products
of policy decisions made both in the private and in the
public sector. Today, in both of these arenas, we are con-
sidering profound economic and social changes, some of
which threaten to raise the degree of chaos to even
higher and less psychologically (and biologically) tolera-
ble levels. The most likely and earliest observed conse-
quences of such a rise are still higher levels of youth
crime and violence, teenage pregnancy and single par-
enthood,16 as well as reduced school achievement, and,
ultimately, a decline in the quality of our nation’s
human capital (Bronfenbrenner et al., 1996).

Thus, we have arrived at a point where the concerns
of basic developmental science are converging with the
most critical problems we face as a nation. That conver-
gence confronts us, both as scientists and as citizens,
with new challenges and opportunities.

TH E BIOECOLOGICAL MODEL: A
DEVELOPMENTAL ASSESSMENT

In this chapter, we have undertaken two challenging
tasks, each an example of science in the discovery mode
with developmental science as its subject matter. The
first was to describe a next stage in the evolution of an
ecological theory of human development, first introduced
more than 20 years ago. The second task was unintended,
but nevertheless begun, for this chapter also documents
early steps in the design of a third-generation model.

As one of those early steps, we found it necessary to
spell out the requirements for conducting developmental
research in the discovery mode. To our knowledge, this
is a first effort to do so systematically, and may there-

References 825

fore receive—and deserve—more criticism than any
other section in the chapter. But at least readers will
know what criteria we were trying to meet and will have
a basis for assessing the validity of the proposed strat-
egy as ref lected in the more differentiated theoretical
and operational models emerging from the successive
confrontations between theory and data.

Among the more promising products of this effort is
the demonstration of the power of proximal processes as
the engines of development, and their systematic varia-
tion as a function of the characteristics of both Person
and Context. We have also presented evidence that, in
accord with specifications of the bioecological model,
different pathways through space and time lead to dif-
ferent outcomes. In this regard, distinctions between
two types of outcome appear especially relevant: (1) be-
tween outcomes of competence versus dysfunction and
(2) between activities focusing primarily on interper-
sonal relationships versus objects and symbols. A third
potentially productive contrast speaks to the question of
who develops and who doesn’t by identifying disposi-
tional characteristics of the Person that are developmen-
tally generative versus developmentally disruptive. Two
additional Person characteristics deemed consequential
for development are also distinguished and illustrated.
The first are resources in terms of ability and acquired
knowledge and skill. The second are demand character-
istics that attract or encourage progressively more com-
plex interaction. An analogous taxonomy is proposed for
the quality of environments, accompanied by illustra-
tions of their corresponding differential effects on prox-
imal processes and outcomes. In each instance, the
evolving tentative hypotheses derived from successively
more differentiated formulations based on the bioeco-
logical model are accompanied by their operational
analogs in terms of corresponding research designs and
the findings generated by them.

The discovery process points also to the scientific
need and benefit of including, in research designs for the
same subjects, two different developmental outcomes
that complement each other. For theoretical reasons de-
riving from the bioecological model, likely to be even
more productive would be the inclusion in the same re-
search design of two different, but theoretically comple-
mentary proximal processes.

Finally, in our view, the most scientifically promising
formulation emerging from the discovery process docu-
mented in this chapter is easily stated, but it is also one
that presents the greatest theoretical challenge:

The four def ining components of the bioecological model
should be theoretically related to each other and to the de-
velopmental outcomes under investigation. This means
that the choice of variables to represent each of the def in-
ing properties should be based on explicit assumptions
about their presumed interrelations.

This may seem a disappointing conclusion for so long
an exposition. Perhaps, even more in developmental sci-
ence than in other fields, the pathways to discovery are
not easy to find. The trails are not marked, there are
many dead ends, the journey is far longer than expected,
and at the end, little may be there. What counts is what
one learns along the way and passes on to future explor-
ers of the uncharted terrain. Here are some final ideas
for those of you whose work will fill the future land-
scape of developmental science. At this still early mo-
ment in the twenty-first century, we are left with a
troubling question: From the perspective of the bioeco-
logical model, what is the prospect for the future devel-
opment of our species? The answer to that question lies
with the willingness of the United States and other eco-
nomically developed countries to heed the emerging les-
sons of developmental science. At the moment, it is
difficult to know what the answer will be. The future
could go either way. Given this alternative, it becomes
the responsibility of developmental science to communi-
cate such knowledge as we possess, and to do so in
words that can still find an echo. Here is a first draft:

In the United States it is now possible for a youth, female
as well as male, to graduate from high school, or univer-
sity, without ever caring for a baby; without ever looking
after someone who was ill, old, or lonely; or without com-
forting or assisting another human being who really
needed help. The developmental consequences of such a
deprivation of human experience have not as yet been sci-
entif ically researched. But the possible social implications
are obvious, for—sooner or later, and usually sooner—all
of us suffer illness, loneliness, and the need for help, com-
fort , and companionship. No society can long sustain it-
self unless its members have learned the sensitivities,
motivations, and skills involved in assisting and caring for
other human beings.

REFERENCES

Ability test ing [Special sect ion]. (1992). Psychological Science,
3, 266 –278.

Ainsworth, M. D., Blehar, M. C., Waters, I., & Wall, S. (1978). Pat-
terns of attachment: A Psychological Study of the Strange Situa-
tion. Hillsdale, NJ: Erlbaum.

826 The Bioecological Model of Human Development

Allport , G. W. (1937 ). Personalit y: A psychosocial interpretation.
New York: Holt.

Bandura , A. (1977 ). Self-eff icacy: Toward a unifying theory of be-
havior change. Psychological Review, 84, 191–215.

Bandura , A. (1982). Self-eff icacy mechanism in human agency.
American Psychologist, 37, 122–147.

Beckwith, L., & Cohen, S. E. (1984). Home environment and
cognitive competence in preterm children during the f irst 5
years. In Allen W. Gottfried ( Ed.), Home environment and
early cognitive development ( pp. 235–271). New York: Aca-
demic Press.

Beckwith, L., Rodning, C., & Cohen, S. (1992). Preterm children
at early adolescence and continuity and discontinuity in mater-
nal responsiveness from infancy. Child Development, 63,
1198–1208.

Bergman, L. R., Cairns, R. B., Nilsson, L.-G., & Nysted, L. ( Eds.).
(2000). Developmental science and the holistic approach. Mah-
wah. NJ: Erlbaum.

Block, J., Block, J. H., & Keyes, S. (1988). Longitudinally foretelling
drug usage in adolescence: Early childhood personality and envi-
ronmental precursors. Child Development, 59, 336 –355.

Block, J. H., & Block, J. (1980). The role of ego-control and ego-re-
siliency in the organization of behavior. In W. A. Collins ( Ed.),
Minnesota Symposia on Child Psychology ( Vol. 13, pp. 39–101).
Hillsdale, NJ: Erlbaum.

Booth, C. L., Rose-Krasnor, L., McKinnon, J., & Rubin, K. H. (1994).
Predicting social adjustment in middle childhood: The role of pre-
school attachment security and maternal style. Social Develop-
ment, 3(3), 189–204.

Bowlby, J. (1969). Attachment and loss: Vol. 1. Attachment. New
York: Basic Books.

Bowlby, J. (1973). Attachment and loss: Vol. 2. Separation. New York:
Basic Books.

Bronfenbrenner, U. (1958). Socialization and social class through
time and space. In E. E. Maccoby, T. M. Newcomb, & E. L. Hart-
ley ( Eds.), Readings in social psychology ( pp. 400 – 425). New
York: Holt , Rinehart and Winston.

Bronfenbrenner, U. (1970). Children and parents ( Report of Forum
15, pp. 241–255). Washington, DC: U.S. Government Printing
Off ice.

Bronfenbrenner, U. (1974). Developmental research, public policy,
and the ecology of childhood. Child Development, 45, 1–5.

Bronfenbrenner, U. (1975). Reality and research in the ecology of
human development. Proceedings of the American Philosophical
Societ y, 119, 439– 469.

Bronfenbrenner, U. (1977a ). Lewian space and ecological substance.
Journal of Social Issues, 33, 199–212.

Bronfenbrenner, U. (1977b). Toward an experimental ecology of
human development. American Psychologist, 32, 513–531.

Bronfenbrenner, U. (1979a ). Contexts of child rearing. American
Psychologist, 34, 844 –858.

Bronfenbrenner, U. (1979b). The ecology of human development: Ex-
periments by nature and design. Cambridge, MA: Harvard Uni-
versity Press.

Bronfenbrenner, U. (1981). Die Oekologie der menschlichen Ent-
wicklung. Stuttgart , Germany: Klett-Cotta.

Bronfenbrenner, U. (1986a , July 23). A generation in jeopardy: Amer-
ica’s hidden family policy. Testimony presented to the committee
on Rules and Administration, Washington, DC.

Bronfenbrenner, U. (1986b). Recent advances in research on the ecol-
ogy of human development. In R. K. Silbereisen, K. Eyferth, & G.
Rudinger ( Eds.), Development as action in context: Problem be-
havior and normal youth development ( pp. 286 –309). New York:
Springer-Verlag.

Bronfenbrenner, U. (1989a ). Ecological systems theory. In R. Vasta
( Ed.), Annals of child development: Six theories of child develop-
ment-Revised formulations and current issues ( pp. 187–249). Lon-
don: JAI Press.

Bronfenbrenner, U. (1989b). The ecology of the family as a context
for human development: Research perspectives. Developmental
Psychology, 22, 723–742.

Bronfenbrenner, U. (1989c). Who cares for children? Paris: United
Nations Educational, Scientif ic and Cultural Organization.

Bronfenbrenner, U. (1990). Oekologische sozialisationsforschung.
In L. Kurse, C.-F. Graumann, & E.-D. Lantermann ( Eds.),
Oekologische psychologie: Ein handbuch in schlusselbegrif fen
( pp. 76 –79). Munich, Germany: Psychologie Verlags Union.

Bronfenbrenner, U. (1992). Child care in the Anglo-Saxon mode. In
M. E. Lamb, K. J. Sternberg, C. P. Hwang, & A. G. Broberg ( Eds.),
Child care in context ( pp. 281–291). Hillsdale, NJ: Erlbaum.

Bronfenbrenner, U. (1993). The ecology of cognitive development:
Research models and fugitive f indings. In R. H. Wozniak & K.
Fischer ( Eds.), Scientific environments ( pp. 3– 44). Hillsdale, NJ:
Erlbaum.

Bronfenbrenner, U. (1994). Ecological models of human develop-
ment. In T. Husen & T. N. Postlethwaite ( Eds.), International en-
cyclopedia of education (2nd ed., Vol. 3, pp. 1643–1647 ). Oxford,
England: Pergamon Press/ Elsevier Science.

Bronfenbrenner, U. (1995). Developmental ecology through space
and time: A future perspective. In P. Moen, G. H. Elder Jr., & K.
Lüscher ( Eds.), Examining lives in context: Perspectives on the
ecology of human development ( pp. 619– 648). Washington, DC:
American Psychological Association.

Bronfenbrenner, U. (2005). Making human beings human. Thousand
Oaks, CA: Sage.

Bronfenbrenner, U., & Ceci, S. J. (1993). Heredity, environment and
the question “ How?”: A new theoretical perspective for the
1990s. In R. Plomin & G. E. McClearn ( Eds.), Nature, nurture,
and psychology ( pp. 313–324). Washington, DC: American Psy-
chological Association.

Bronfenbrenner, U., & Ceci, S. J. (1994a ). Nature-nurture reconcep-
tualized: A bioecological model. Psychological Review, 101,
568–586.

Bronfenbrenner, U., & Ceci, S. J. (1994b). “The Bell Cur ve”: Are
today’s “New Interpreters” espousing yesterday’s science? Unpub-
lished manuscript , Cornell University, Department of Human De-
velopment and Family Studies, Ithaca , NY.

Bronfenbrenner, U., & Crouter, A. C. (1982). Work and family
through time and space. In S. Kamerman & C. D. Hayes ( Eds.),
Children in a changing world ( pp. 39–83). Washington, DC: Na-
tional Academy Press.

Bronfenbrenner, U., & Crouter, A. C. (1983). The evolution of en-
vironmental models in developmental research. In W. Kessen
(Series Ed.) & P. H. Mussen ( Vol. Ed.), Handbook of child psy-
chology: Vol. 1. History, theory, and methods (4th ed.,
pp. 357– 414). New York: Wiley.

Bronfenbrenner U., & Evans, G. W. (2000). Developmental science
in the 21st century: Emerging questions, theoretical models, re-

References 827

search designs, and empirical f indings. Social Development,
9(1), 15–25.

Bronfenbrenner, U., McClelland, P., Wethington, E., Moen, P., &
Ceci, S. J. (1996 ). The state of Americans: This generation and
the next. New York: Free Press.

Bronfenbrenner U., & Morris, P. A. (1998). The ecology of develop-
mental processes. In R. M. Lerner ( Ed.), Handbook of Child Psy-
chology (5th ed., Vol. 1, pp. 993–1028). New York: Wiley.

Bronfenbrenner, U., & Neville, P. R. (1994). America’s children and
families: An international perspective. In S. L. Kagan &
B. Weissbourd ( Eds.), Putting families first ( pp. 3–27 ). San Fran-
cisco: Jossey-Bass.

Cairns, R. B. (1970). Towards a unif ied science of development. Con-
temporary Psychology, 15, 214 –215.

Cairns, R. B., & Cairns, B. D. (1994). Lifelines and risks: Pathways
to youth in our time. Cambridge, England: Cambridge Univer-
sity Press.

Cohen, S. E., & Beckwith, L. (1979). Preterm infant interaction with
the caregiver in the f irst year of life and competence at age two.
Child Development, 50, 767–776.

Cohen, S. E., Beckwith, L., & Parmelee, A. H. (1978). Receptive lan-
guage development in preterm children as related to caregiver-
child interaction. Pediatrics, 61, 16 –20.

Cohen, S. E., & Parmelee, A. H. (1983). Prediction of 5-year Stanford-
Binet scores in preterm infants. Child Development, 54, 1242–1253.

Cohen, S. E., Parmelee, A. H., Beckwith, L., & Sigman, M. (1986 ).
Developmental and Behavioral Pediatrics, 7, 102–110.

Cole, M. (1995). Culture and cognitive development: From cross-cul-
tural research to creating systems of cultural mediation. Culture
and Psychology, 1, 25–54.

Conger, R. D., & Elder, G. H., Jr. (1994). Families in troubled times:
Adapting to change in rural America. Chicago: Aldine de Gruyter.

Connolly, J. A., & Doyle, A. (1984). Relation of social fantasy play to
social competence in preschoolers. Developmental Psychology,
20, 797–806.

Drillien, C. M. (1957 ). The social and economic factors af fecting the
incidence of premature birth. Journal of Obstetrical Gynecology,
British Empire, 64, 161–184.

Drillien, C. M. (1964). Growth and development of the prematurely
born infant. Edinburgh, Scotland: Livingstone.

Elder, G. H., Jr. (1974). Children of the great depression. Chicago:
University of Chicago Press.

Elder, G. H., Jr. (1986 ). Military times and turning points in men’s
lives. Developmental Psychology, 22, 233–245.

Elder, G. H., Jr. (1998). Life course and development. In W. Damon
( Editor-in-Chief ) & R. M. Lerner ( Vol. Ed.), Handbook of child
psychology: Vol. 1. Theoretical models of human development (5th
ed., pp. 1–24). New York: Wiley.

Elder, G. H., Jr., Eccles, J. S., Ardelt , M., & Lord, S. (1995). Inner city
parents under economic pressure: Perspectives on the strategies of
parenting. Journal of Marriage and the Family, 57, 771–784.

Elder, G. H., Jr., King, V., & Conger, R. D. (1996 ). Intergenera-
tional continuity and changes in rural lives: Historical and
developmental insights. International Journal of Behavioral
Development, 10, 439– 466.

Elder, G. H., Jr., Shanahan, M. J., & Clipp, E. C. (1994). When war
comes to men’s lives: Life course patterns in family, work, and
health. Psychology and Aging, 9, 5–16.

Elder, G. H., Jr., Van Nguyen, T. V., & Caspi, A. (1985). Linking fam-
ily hardship to children’s lives. Child Development, 56, 361–375.

Elder, G. H., Jr., Wu, W., & Jihui, Y. (1993). State-initiated change
and the life course in Shanghai, China ( Unpublished project re-
port ). Chapel Hill, NC: Carolina Population Center.

Fischbein, S. (1980). IQ and social class. Intelligence, 4, 51– 63.

Garmezy, N., & Rutter M. (1983). Stress, coping, and development in
children. New York: McGraw-Hill.

Heath, A. C., Berg, K., Eaves, L. J., Solaas, M. H., Corey, L. A., Sun-
det , J., et al. (1985). Educational policy and the heritability of ed-
ucational attainment. Nature, 314, 734 –736.

Hetherington, E. M., & Clingempeel, W. G. (1992). Coping with mar-
ital transitions. Monographs of the Societ y for Research in Child
Development, 57(2/3).

Jenkins, J. M., & Smith, M. A. (1990). Factors protecting children liv-
ing in disharmonious homes: Maternal reports. Journal of the
American Academy of Child and Adolescent Psychiatry, 29, 60 – 69.

Kohn, M. L., & Slomczynski, K. M. (1990). Social structure and self-
direction: A comparative analysis of the United States and Poland.
Oxford, England: Basil Blackwell.

Langer, E. J., & Rodin, J. (1976 ). The ef fects of choice and enhanced
personal responsibility for the aged: A f ield experiment in an in-
stitutional setting. Journal of Personalit y and Social Psychology,
34, 191–198.

Lerner, R. M. (1982). Children and adolescents as producers of their
own development. Developmental Review, 2, 342–370.

Lerner, R. M. (1995). The limits of biological inf luence: Behavioral
genetics as the emperor’s new clothes [Review of the book The
limits of family inf luence]. Psychological Inquiry, 6, 145–156.

Lerner, R. M. (2002). Concepts and theories of human development
(3rd ed.). Mahwah, NJ: Erlbaum.

Lerner, R. M. (2004a ). Genes and the promotion of positive human
development: Hereditarian versus developmental systems per-
spectives. In C. Garcia Coll, E. Bearer, & R. M. Lerner ( Eds.),
Nature and nurture: The complex interplay of genetic and environ-
mental inf luences on human behavior and development ( pp. 1–33).
Mahwah, NJ: Erlbaum.

Lerner, R. M. (2004b). Libert y: Thriving and civic engagement among
America’s youth. Thousand Oaks, CA: Sage.

Lerner, R. M., & Busch-Rossnagel, N. A. ( Eds.). (1981). Individual as
producers of their development: A life-span perspective. New York:
Academic Press.

MacDonald, K., & Parke, R. D. (1984). Bridging the gap: Parent-
child play interaction and peer interactive competence. Child De-
velopment, 55, 1265–1277.

Main, M., & Weston, D. R. (1981). The quality of the toddler’s rela-
tionship to mother and to father : Related to conf lict behavior and
the readiness to establish new relationships. Child Development,
52, 932–940.

Marrow, A. J. (1977 ). The practical theorist: The life and work of
Kurt Lewin. New York: Teachers College Press.

May, M. A. (1932). The foundations of personality. In P. S. Achilles
( Ed.), Psychology at work ( pp. 81–101). New York: McGraw-Hill.

Mead, G. H. (1934). Mind, self, and societ y. Chicago: University of
Chicago Press.

Moen, P., & Erickson, M. A. (1995). Linked lives: A transgenera-
tional approach to resilience. In P. Moen, G. H. Elder Jr., & K.
Luscher ( Eds.), Examining lives in context: Perspectives on the

828 The Bioecological Model of Human Development

ecology of human development ( pp. 169–210). Washington, DC:
American Psychological Association.

Moorehouse, M. (1986 ). The relationships among continuit y in mater-
nal employment, parent-child communicative activities, and the
child’s social competence. Unpublished doctoral dissertation, Cor-
nell University, Ithaca , NY.

Pastor, D. L. (1981). The quality of the mother-infant interaction and
its relationship to toddlers’ initial sociability with peers. Devel-
opmental Psychology, 17(3), 326 –335.

Plomin, R. (1993). Nature and nurture: Perspective and prospect. In
R. Plomin & G. E. McClearn ( Eds.), Nature, nurture, and psy-
chology ( pp. 459– 486 ). Washington, DC: American Psychological
Association.

Plomin, R., & Bergeman, C. S. (1991). The nature of nurture: Genetic
inf luence on “environmental” measures. Behavioral and Brain
Sciences, 4, 373– 427.

Plomin, R., & McClearn, G. E. ( Eds.). (1993). Nature, nurture, and
psychology. Washington, DC: American Psychological Association.

Plomin, R., Reiss, D., Hetherington, E. M., & Howe, G. W. (1994).
Nature and nurture: Genetic contributions to measures of the
family environment. Developmental Psychology, 30, 32– 43.

Pulkkinen, L. (1983). Finland: The search for alternatives to aggres-
sion. In A. P. Goldstein & M. Segall ( Eds.), Aggression in global
perspective ( pp. 104 –144). New York: Pergamon Press.

Pulkkinen, L., & Saastamoinen, M. (1986 ). Cross-cultural perspec-
tives on youth violence. In S. J. Apter & A. P. Goldstein ( Eds.),
Youth violence: Programs and prospects ( pp. 262–281). New York:
Pergamon Press.

Riksen-Walraven, J. M. (1978). Effects of caregiver behavior on ha-
bituation rate and self-eff icacy in infants. International Journal
of Behavioral Development, 1, 105–130.

Rodin, J., & Langer, E. J. (1977 ). Long-term effects of a control-rele-
vant intervention with the institutionalized aged. Journal of Per-
sonalit y and Social Psychology, 35, 897–902.

Rotter, J. (1966 ). Generalized expectancies for internal versus exter-
nal locus of control of reinforcement. Psychological Monographs:
General and Applied, 80, 1–28.

Rutter, M., & Rutter, M. (1992). Developing minds: Challenge and
continuit y across the life span. New York: Penguin Books.

Scarr, S. (1992). Developmental theories for the 1990s: Development
and individual differences. Child Development, 63, 1–19.

Scar r-Salapatek, S. (1971). Race, social class, and IQ. Science,
174, 1285–1295.

Small, S., & Luster, T. (1990, November). Youth at risk for parent-
hood. Paper presented at the Creating Caring Communities Con-
ference, Michigan State University, East Lansing.

Sroufe, L. A. (1990). An organizational perspective on the self. In D.
Cicchetti & M. Beeghly ( Eds.), The self in transition: Infancy to
childhood ( pp. 281–307 ). Chicago: University of Chicago Press.

Sroufe, L. A., Fox, N. E., & Pancake, V. R. (1983). Attachment and
dependency in developmental perspective. Child Development,
54, 1615–1627.

Steinberg, L., Darling, N. E., & Fletcher, A. C. (1995). Authorita-
tive parenting and adolescent adjustment: An ecological journey.
In P. Moen, G. H. Elder Jr., & K. Luscher ( Eds.), Examining
lives in context: Perspectives on the ecology of human develop-
ment ( pp. 423– 466 ). Washington, DC: American Psychological
Association.

Sundet , J. M., Tambs, K., Magnus, P., & Berg, K. (1988). On the
question of secular trends in the heritability of intelligence test
scores: A study of Nor wegian twins. Intelligence, 12, 47–59.

Terman, L. M. (1925). Genetic studies of genius: Vol. 1. Mental and
physical traits of a thousand gifted children. Stanford, CA: Stan-
ford University Press.

Tobach, E. (1981). Evolutionary aspects of the activity of the organ-
ism and its development. In R. M. Lerner & N. A. Busch-Ross-
nagel ( Eds.), Individuals as producers of their development: A
life-span perspective ( pp. 37– 68). New York: Academic Press.

Tobach, E., & Schneirla , T. C. (1968). The biopsychology of social
behavior of animals. In R. E. Cooke & S. Levin ( Eds.), Biologic
basis of pediatric practice ( pp. 68–82). New York: McGraw-
Hill.

Tulkin, S. R. (1973). Social class differences in infants’ reactions
to mothers’ and stranger’s voices. Developmental Psychology, 8(1),
137.

Tulkin, S. R. (1977 ). Social class differences in maternal and infant
behavior. In P. H. Leiderman, A. Rosenfeld, & S. R. Tulkin
( Eds.), Culture and infancy ( pp. 495–537 ). New York: Academic
Press.

Tulkin, S. R., & Cohler, B. J. (1973). Child-rearing attitudes and
mother-child interaction in the f irst year of life. Merrill-Palmer
Quarterly, 19, 95–106.

Tulkin, S. R., & Covit z, F. E. (1975, April). Mother-infant inter-
action and intellectual functioning at age six. Paper presented at
the meeting of the Society for Research in Child Development ,
Denver, CO.

Tulkin, S. R., & Kagan, J. (1972). Mother-child interaction in the
f irst year of life. Child Development, 43, 31– 41.

Turner, P. J. (1991). Relations between attachment , gender, and behav-
ior with peers in preschool. Child Development, 62, 1475–1488.

Wachs, T. D. (1979). Proximal experience and early cognitive intel-
lectual development: The physical environment. Merrill-Palmer
Quarterly, 25, 3– 42.

Wachs, T. D. (1987a ). The short-term stability of aggregated and
non-aggregated measures of infant behavior. Child Development,
58, 796 –797.

Wachs, T. D. (1987b). Specif icity of environmental action as mani-
fest in environmental correlates of infant’s mastery motivation.
Developmental Psychology, 23, 782–790.

Wachs, T. D. (1989). The nature of the physical microenvironment:
An expanded classif ication system. Merrill-Palmer Quarterly,
35, 399– 402.

Wachs, T. D. (1990). Must the physical environment be mediated by the
social environment in order to inf luence development: A further
test. Journal of Applied Developmental Psychology, 11, 163–170.

Wachs, T. D. (1991). Environmental considerations in studies with
non-extreme groups. In T. D. Wachs & R. Plomin ( Eds.), Con-
ceptualization and measurement of organism-environment inter-
action ( pp. 44 – 67 ). Washington, DC: American Psychological
Association.

Wachs, T. D., & Chan, A. (1986 ). Specif icity of environmental ac-
tions as seen in physical and social environment correlates of
three aspects of 12-month infants’ communication performance.
Child Development, 57, 1464 –1475.

By now, you should have been able to identify that it all goes back to day 1—Self-Definition.  You are who you are based upon the events that have happened in your life, and how you chose to define.  Without further ado, for this assignment, you are to examine how the personal characteristics (i.e., force, resource, demands, etc. ) described by Bronfenbrenner and Morris are pertinent to your existence (e.g., who you are, how you identify, what is your purpose in life, what legacy do you want to leave for forthcoming generations etc.).  In doing so, you will also need to integrate at least one construct from each of the previous sections (please highlight and bold where you have done so).

Please refer to Section 6 (
PREPARING ASSIGNMENTS FOR SUBMISSION
) of the syllabus prior to starting your assignment.  This includes using sections that have well-defined paragraphs.  I will be more critical of your writing, format, and presentation as this is your final writing assignment for this course. 

You will not need references for this assignment, but you must be thorough.  To that end, this assignment should be a minimum of 4 pages (the cover page is page 1).   Please upload a Word doc