WHAT WILL YOU KNOW?
How can the study of children, each one unique, be a science?
Does his or her ethnic group make any difference in a child’s development?
Is childhood today different from childhood fifty years ago?
How can we know what changes between one year of life and the next?
Is it unethical to study children scientifically?
Do scientists always investigate the crucial questions?

The science of human development
…seeks to understand how and why people of all ages and circumstances change or remain the same over time.

Three crucial elements in definition of science of development
• Science
• People
• Change

Scientific method
• Way to answer questions using empirical research and data-based conclusions.
Five basic steps of the scientific method
• Begin with curiosity and pose a question.
• Develop a hypothesis.
• Test the hypothesis.
• Draw conclusions.
• Report the results.

Built into the scientific method —in questions, hypotheses, tests, and replication —is a passion for possibilities, especially unexpected ones.

Replication: The final step
• Repeating a study, usually using different participants, perhaps of another age, SES, or culture

Nature
• Influence of genes we inherit
Nurture
• Environmental influences that affect development
Nature always affects nurture, and nurture always affects nature.

• Differential susceptibility: People differ in their susceptibility to environmental influence because of particular inherited genes.

Biosocial
Development
• Includes all the growth and change that occur in a person’s body and the genetic, nutritional, and health factors that affect that growth and change.
• Motor skills—everything from grasping a rattle to driving a car
—are also part of the biosocial domain.
• In this book, this domain is called biosocial, rather than physical or biological.
Cognitive Development
• Includes all the mental processes that a person uses to obtain knowledge or to think about the environment.
• Cognition encompasses perception, imagination, judgment, memory, and language
—the processes people use to think, decide, and learn.
• Education— not only the formal curriculum in schools but also informal learning —is part of this domain.
Psychosocial Development
• Includes development of emotions, temperament, and social skills.
• Family, friends, the community, the culture, and the larger society are particularly central to the psychosocial domain.
• For example, cultural differences in
“appropriate” sex roles or in family structures are part of this domain.

Are children more important than adults?
• Earlier research focused on child development; adulthood is now studied.
Is childhood more important, influential, and determinative than adulthood?
• The answer is complex and depends in part on the developmental domain being considered.
• All age groups need support; more scientific study is needed.

The challenge
• Identifying both universalities and differences and describing them in ways that simultaneously unify humanity and distinguish each individual
The danger
• Drawing conclusions based on a limited group or, worse, to consider one’s own group normal and every other group abnormal ( difference-equalsdeficit error )

Sexual orientation
• Illustrates a difference that was once assumed to be a deficit
• Led to bullying of LGBT classmates
• Is less likely to be perceived as deficit today due to activism, scientific data, and cultural change

Including All Kinds of
People
Important definitions
• Culture
• Ethnic group
• Race
• Socioeconomic status
(SES)

Widening Gap Between the Rich and the
Poor at Different Ages

In the science of human development
• Important to find the right balance between the universal and the particular
• Necessary to guard against simple conclusions across or within groups
• Key to remember that most categories are social constructions, not enduring divides

Critical period
• Time when a particular type of developmental growth (in body or behavior) must happen for normal development to occur.
Sensitive period
• Time when a certain type of development occurs more easily, although it may still happen later with more difficulty.

Ecological-systems approach
(Bronfenbrenner)
• Each person is affected by many social contexts and interpersonal interactions.
• Nested levels surround individuals and affect them.
• Approach later named bioecological theory.

Ecological Systems
• Microsystems
• Exosystems
• Macrosystems
• Mesosystem
• Chronosystem

Historical context: Cohort
• Born within the same historical period
• Move through life together
• Experience same events, new technologies, and cultural shifts at the same ages
• Influences attitudes and behaviors

Plasticity
• Suggests abilities, personality, and other human characteristics can change over time
• Simultaneous incorporates two facts
• People can change over time
• New behavior depends partly on what has already happened
• Is evident in dynamic-systems approach

This classroom scene reflects the eagerness for education felt by many immigrants, the reticence of some boys in an academic context, and a global perspective (as demonstrated by the world map).
These facets emerge from various systems —family, gender, and culture—and they have interacted to produce this moment.

Statistical measures often used to analyze research results
• Effect size
• Significance
• Cost-benefit analysis
• Odds ratio
• Factor analysis
• Meta-analysis

Three basic types of research designs
• Observation
• The experiment
• The survey

Scientific observation
• Requires researcher to record behavior systematically and objectively
• May be conducted in a naturalistic setting or a laboratory
• Is crucial to development of hypotheses

Experiment
• Establishes causal relationships among variables
Variables
• Independent variable
• Dependent variable
Groups
• Experimental group
• Comparison group

1.
Divide participants into two groups that are matched on important characteristics, especially the behavior that is the dependent variable on which this study is focused.
2.
Give special treatment, or intervention (the independent variable), to one group (the experimental group).
3.
Compare the groups on the dependent variable. If they now differ, the cause of the difference was probably the independent variable.
4.
Publish the results.

Survey
• Includes information collected from a large number of people by interview, questionnaire, or some other means
Challenges
• Acquiring valid survey data is not easy.
• Some people lie, some change their minds.
• Survey answers are influenced by the wording and the sequence of the questions.

Did You Have Sexual
Intercourse Before Age
Thirteen?
I Forgot?
If this were the only data available, you might conclude that ninthgraders have suddenly become more sexually active than twelfthgraders.
But we have 20 years of data —those who are ninth-graders now will answer differently by twelfth grade.

Basic research designs
• Cross-sectional research
• Longitudinal research
• Cross-sequential research

Which approach is best?
• Cross-sectional research: Most convenient, quickest, and least expensive way to study developmental change over time; does not always indicate processes of development
• Longitudinal research: Useful in studying development over many years; uncovers links that cross-sectional research does not; more time and resource intensive
• Cohort-sequential research: Allows disentanglement of age and historical context

Correlation and causation
• A correlation exists between two variables if one variable is more (or less) likely to occur when the other does
• Positive correlation
• Negative correlation
• Zero correlation
• Correlation is not causation!

Quantitative research
• Provides data that is numerical, and is best to compare children in different contexts and cultures
• Is easier to replicate, interpret, and verify
Qualitative research
• Best captures the nuance of individual lives
• Reports information without being quantified

Vaccination and
Autism
• Suspicion of science and federal government has led some parents not to vaccinate their child.
• Some parents believe that that certain childhood vaccinations cause autism spectrum disorder.
What would you say to a parent who asked you if this is true?
What advice would you give regarding childhood vaccination?

Each academic discipline and professional society involved in the study of human development has a code of ethics.
• In U.S., most educational and medical institutions have an Institutional Review Board

Protection of research participants
• Most important safeguard ensures no harm occurs.
• Participants must understand and agree to research procedures (informed consent).
Integrity of scientific study
• Methods and conclusions must promote accuracy, honesty, and truthfulness.

The ultimate purpose of the science of human development is to help “all kinds of people, everywhere, of every age” live satisfying and productive lives.