Chapter 1: Introduction
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The first chapter introduces the study of human development.
The first section defines development, briefly describing the
how, why, and who of this definition. The second section
identifies five characteristics of the life-span perspective on
human development and explains different aspects of the
overlapping contexts in which people develop. The story of
David illustrates the importance of human plasticity. The
ecological-systems approach is Bronfenbrenner’s description of
how the individual is affected by, and affects, many other
individuals, groups of individuals, and larger systems in the
environment.
The next section discusses the strategies developmentalists
use in their research, including scientific observation,
experiments, and surveys. To study people over time,
developmentalists have created several research designs: crosssectional, longitudinal, and cross-sequential.
The final section discusses several common mistakes that
can be made in interpreting research, including the mistake of
confusing correlation with causation and the ethics of research
with humans. In addition to ensuring confidentiality and safety,
developmentalists who study children are especially concerned
that the benefits of research outweigh the risks.
Chapter Guide
I.
Defining Development
1. The science of human development seeks to understand how
and why people—all people, everywhere, of every age—
change over time, and how and why they remain the same.
2. Development is multidirectional, multicontextual,
multicultural, multidisciplinary, and plastic.
3. The science of human development is empirical, meaning
that it focuses on data, facts, observation, and
experimentation.
4. The scientific method consists of five basic steps: (1)
formulate a research question, (2) develop a hypothesis, (3)
test the hypothesis, (4) draw conclusions, and (5) make the
findings available.
5. Replication of research findings verifies the findings and
leads researchers to more definitive and extensive
conclusions. In replicating research, scientists use different
participants.
6. The nature–nurture debate is the question of how much of
any characteristic is the result of genes (nature) and how
much is the result of experience (nurture). Genes and
environment affect every aspect of development.
7. The fact that nature and nurture interact helps clarify another
question: whether or not timing is crucial. Research has
shown that there are both critical periods and sensitive
periods in development.
8. The value of understanding that nature and nurture interact
also can be seen in research on the origins of violence in
young people. One study found that mistreated boys were
more likely to be overly aggressive if they had a particular
variation in the MAOA gene (the low-MAOA gene).
However, even if they inherited the gene that produces low
levels of the enzyme monoamine oxidase A, boys who had
not been mistreated tended to become peaceable adults.
9. The emphasis on the interaction between people and within
each person is highlighted by the dynamic-systems theory,
which stresses fluctuations and transitions.
II.
The Life-Span Perspective
1. The life-span perspective views human development as
multidirectional, multicontextual, multicultural,
multidisciplinary, and plastic.
2. Change is apparent in each aspect of life and in every
direction. Research shows that some shifts are stage-like and
other shifts are gradual.
3. The approach that emphasizes the influence of the systems,
or contexts, that support the developing person is Urie
Bronfenbrenner’s ecological-systems approach. According
to this model, human development is supported by systems
at four nested levels: the microsystem (immediate social
setting), the exosystem (local, such as school and church),
the macrosystem (cultural values, political processes,
economic policies, and social conditions), and the
chronosystem, which emphasizes the importance of
historical time on development. A fifth system, the
mesosystem, connects systems, for example, the interface
between home and school. As a reflection of the impact of
biology on development, Bronfenbrenner renamed his theory
bioecological theory.
4. Developmentalists take a broad view of development,
recognizing the influence on development of external forces,
that is, the context of development. This larger perspective
makes it imperative that development be understood in its
social context, including its historical and socioeconomic
contexts.
5. A cohort is a group of people born within a few years of
each other who tend to share certain historical events and
cultural shifts.
6. Socioeconomic status (SES) is determined by several
overlapping variables, including income, wealth, education,
place of residence, and occupation. Although low income
obviously limits a person, other SES factors (such as
education) can make poverty better or worse.
7. Culture affects development in a multitude of interrelated
ways, from whether to cover your mouth when laughing to
what to eat for breakfast.
8. An ethnic group is a collection of people who share certain
attributes, such as ancestry, national origin, religion, and
language.
9. Although race was once defined as a biological category, it
is actually a social construction, an idea that is built on
shared perceptions, not on objective reality, and, unlike
genetic differences, social constructions can change.
10. The value of an interdisciplinary approach to understanding
human development can be seen in research on mirror
neurons, which are brain cells that respond to the observed
actions of others. These neurons, which in the human brain
reflect not only the movements but also the intentions,
sensations, and emotions of those around us, may help
explain some autism, language learning, empathy for other
people, and how culture is transmitted.
11. One of the most encouraging aspects of the science of
development is that development is characterized by
plasticity, or the capability of change.
III.
Using the Scientific Method
1. There are many ways to test hypotheses. One method is
scientific observation of people in their natural environment,
in a laboratory setting, or in searches of archival data.
Observation is limited in that it does not tell us what causes
people to do what they do.
2. Experiments can reveal cause-and-effect relationships by
allowing experimenters to observe whether a change in an
independent variable affects some specific behavior, or
dependent variable. In an experiment, the participants who
receive a particular treatment constitute the experimental
group; the participants who do not receive the treatment
constitute the comparison group (control group).
3. The survey is a quick and direct way to obtain data.
However, it is especially difficult to get valid data from a
survey: Some people may refuse to answer, and others may
give answers to make themselves look better. Survey
answers also are influenced by the wording and the sequence
of the questions.
4. In cross-sectional research, groups of people who are
different in age but similar in all other important ways are
compared on the characteristic that is of interest to the
researcher(s). One limitation of cross-sectional research is
that it is always possible that some variable other than age
differentiates the groups.
5. In longitudinal research, the same people are studied over a
period of time. Longitudinal research is particularly useful in
studying developmental trends that occur over a long age
span.
6. Both longitudinal and cross-sectional researchers must bear
in mind that research on a cohort may not be valid for people
developing in an earlier or later cohort.
7. In cross-sequential research, several groups of people at
different ages (crosssectional component) are followed over time (longitudinal
component).
IV.
Cautions from Science
1. Correlation is a number indicating the degree of relationship
between two variables. A correlation is positive if both
variables tend to increase together or decrease
together, negative if one variable tends to increase when the
other decreases, and zero if no connection is evident.
Correlation does not prove causality.
2. Because numbers can be easily summarized and compared,
scientists often rely on data produced by quantitative
research. This method may be particularly limiting when
researchers describe child development. Also, many
developmental researchers use qualitative research that asks
open-ended questions.
3. When studying people, scientists take special care to ensure
that participation is voluntary and harmless and that the
study’s benefits outweigh its costs. They do this by
establishing a code of ethics for researchers to follow, which
is enforced by the Institutional Review Board (IRB) at most
educational and medical institutions.