The Psychology of Human Development David F. Bjorklund
Why Study Development? • “The child is the father of man (and the mother of woman)” - to understand adults, including ourselves • To understand human nature • To foster development and well-being (optimization)
Goals of Studying Life-Span Development • Description • Normal development, individual differences • Explanation • Typical and individually different development • Optimization • Positive development, enhancing human capacities • Prevention and overcoming difficulties
What is Development? • Systematic changes and continuities • In the individual • Between conception and death • “Womb to Tomb” • Three broad domains • Physical, Cognitive, Psychosocial
Types of “change over time” • Ontogeny: changes in the individual over the course of his or her lifetime • Phylogeny: development of the species (i.e., evolution) • Maturation: a biological unfolding of the individual according to a genetic plan. • Learning:relatively permanent changes in thoughts, feelings, or behaviors as a result of experience, that usually occur over brief periods • Growth: Physical changes that occur from birth to maturity • Aging: Positive and negative changes in the mature organism
Development: Changes in structure or function over time • Structure refers to some substrate of the organism, such as nervous tissue, muscle, or limbs, or—in cognitive psychology—the mental knowledge that underlies intelligence. • Function denotes actions related to a structure and can include actions external to the structure being studied, such as neurochemical or hormonal secretions, and other exogenous factors that can best be described as “experience”—that is, external sources of stimulation.
Development is characteristic of the species and has its basis in biology. Its general course, therefore, is relatively predictable. Development progresses as a result of bidirectional, or reciprocal, relationship between structure and function, and can be expressed as: • structure function.
A Brief History of Childhood • Childhood as a sociological concept • Infanticide legal in much of ancient world and common in Europe through middle ages (abandonment outlawed in Europe in 1600s) • Oblation: leaving infants with religious organizations • Children incorporated into daily lives of adults • 50% of children died before age 5 until 1800s • Enlightenment: Jean Jacques Rousseau: children are important in their own right, and are not merely a means to an end (that is, adulthood).
Literacy and Education • Postman: invention of moveable type changed definition of adulthood (being literate); necessitated schooling and “the invention” of childhood
Life Expectancy at Birth for Different Countries: 2000 • Andorra: 83.5 Brazil: 62.9 • San Marino: 81.1 Cambodia: 56.5 • Japan: 80.7 South Africa: 51.1 • Sweden: 79.6 Haiti: 49.2 • Italy: 79.0 Somalia: 46.2 • United States: 77.1 Afghanistan: 45.9 • China: 71.4 Uganda: 42.9 • Vietnam: 69.3 Botswana: 39.3 • Iraq: 66.5 Angola: 38.3 • Egypt: 63.3 Malawi: 37.6 • India: 62.5 Zambia: 37.2
Issues in Lifespan Development • The Stability and Plasticity of Human Behavior: The Effects of Early Experiences and the Changeability of Behavior • Continuity vs. Discontinuity: The “Stages Debate,” or Understanding How Development Progresses • Normative vs. Idiographic Approaches: Developmental Function and Individual Differences • Nature vs. Nurture: About the Role of Genetics and Environment in Human Development
The Stability and Plasticity of Human Behavior • Stability refers to the degree to which people maintain their same rank order in comparison to other children with respect to some characteristic • Plasticity refers to the ability to change as a result of experience.
Continuity vs. Discontinuity • Stages of Development • Qualitative versus Quantitative Differences • Continuity versus Discontinuity • Homogeneity of Cognitive Function
Some abilities, such as language, are more easily acquired during a critical, or sensitive, time in development
Framing the Nature/Nurture Issue • Nature: heredity(nativism) • Maturational processes guided by genes • Biologically based predispositions • Biological unfolding of genes • Genetic determinism • Nurture: environment (empiricism) • Learning: experiences cause changes is thoughts, feelings, and behaviors • Environmental determinism • Interactionist view: nature & nurture interact
Caspi et al., 2002 • monoamine oxidase A (MAOA) associated with antisocial behavior in rats and humans • Gene on X chromosome controls MAOA (high versus low levels) • Examined antisocial behavior in boys with high and low levels of MAOA as function of childhood maltreatment
Relationship between childhood maltreatment (none, probable, severe) and MAOA activity (low versus high) on antisocial behavior.
Methods of Studying Life-Span Development • Historical • Baby Biographies: Charles Darwin • Questionnaires: G. Stanley Hall • Key Assumptions of Modern Life-Span Perspectives • Lifelong, multidirectional process • Gain and loss and lifelong plasticity • Historical/cultural contexts, multiple influences • Multi-disciplinary studies
Conducting Developmental Research • Self-reports: interview, questionnaires, tests • Behavioral Observations • Naturalistic • Advantage: natural setting • Disadvantage: conditions not controlled • Structured (Lab) • Disadvantage: cannot generalize to natural settings • Advantage: conditions controlled
The Experimental Method • Three Critical Features • 1. Manipulation of independent variable • 2. Random assignment of individuals to treatment conditions • 3. Experimental control • Quasi-Experiment: No random assignment
The Correlational Method • Determine if 2 or more variables are related • Correlation: A measure of the relationship • Can range from +1.0 to –1.0 • Positive: variables move in same direction • Negative: variables move in opposite dir. • No relationship if correlation is 0 • Cannot establish a causal relationship
Developmental Research Designs • Cross-Sectional Designs • +1 cohorts or age-groups studied • 1 time of testing • Studying age differences at any one time • Longitudinal Designs • 1 cohort • +1 time of testing • Study changes across time in one cohort
Age, Cohort, and Time of Measurement Effects • Age effects: Changes which occur due to age • Cohort Effects: Born in one historical context • Changes due to differences in society • Disadvantage of cross-sectional design • Time of measurement effects: Historical • Takes place at time of data collection • Disadvantage of longitudinal design
Sequential Designs • A combination of cross-sectional and longitudinal designs • Advantages of both designs • Gives information about • Which age-related trends are age effects? • Which age-related trends are truly cohort effects? • Which age-related trends are a result of historical events?
Protecting the Rights of Participants • Risk to benefit balance of the research • Researcher responsibilities • Informed consent • Debriefing • Protection from harm • Confidentiality
Ethical Standards for Research with Children • Doing research with children involves all the same ethical considerations when one does research with adults, plus some additional ones. The principles listed below were published in the 1990-91 Directory of the Society for Research in Child Development (SRCD), except for Principles 15 and 16, first published in the Fall 1991 Newsletter. • Principle 1. Non-harmful procedures: The investigator should use no research operation that may harm the child either physically or psychologically. The investigator is also obligated at all times to use the least stressful research operation whenever possible. . . When the investigator is in doubt about the possible harmful effects of the research operations, consultation should be sought from others. .
Principle 2.Informed Consent: Before seeking consent or assent from the child, the investigator should inform the child of all features of the research that may affect his or her willingness to participate and should answer the child’s questions in terms appropriate to the child’s comprehension. The investigator should respect the child’s freedom to choose to participate in the research or not by giving the child the opportunity to give or not give assent to participation as well as to choose to discontinue participation at any time. . . Investigators working with infants should take special effort to explain the research procedures to the parents and be especially sensitive to any indicators of discomfort in the infant. . .
Principle 3.Parental consent: The informed consent of parents, legal guardians or those who act in loco parentis (e.g., teachers, superintendents of institutions) similarly should be obtained, preferably in writing. Informed consent requires that parents or other responsible adults be informed of all the features of the research that may affect their willingness to allow the child to participate. This information should include the profession and institution affiliation of the investigator. Not only should the right of the responsible adults to refuse consent be respected, but they should be informed that they may refuse to participate without incurring any penalty to them or to the child.
Principle 4. Additional consent: The informed consent of any persons, such as school teachers for example, whose interaction with the child is the subject of the study should also be obtained. . • Principle 5.Incentives: Incentives to participate in a research project must be fair and must not unduly exceed the range of incentives that the child normally experiences. . . . • Principle 6.Deception: Although full disclosure of information during the procedure of obtaining consent is the ethical ideal, a particular study may necessitate withholding certain information or deception. Whenever withholding information or deception is judged to be essential to the conduct of the study, the investigator should satisfy research colleagues that such judgment is correct. . . • Principle 7.Anonymity: To gain access to institutional records, the investigator should obtain permission from responsible authorities in charge of records. Anonymity of the information should be preserved and no information used other than that for which permission was obtained.
Principle 8.Mutual responsibilities: From the beginning of each research investigation, there should be clear agreement between the investigator and the parents, guardians or those who act in loco parentis, and the child, when appropriate, that defines the responsibilities of each. The investigator has the obligation to honor all promises and commitments of the agreement. • Principle 9.Jeopardy: When, in the course of research, information comes to the investigator’s attention that may jeopardize the child’s well-being, the investigator has a responsibility to discuss the information with the parents or guardians and with those expert in the field in order that they may arrange the necessary assistance for the child. • Principle 10.Unforeseen consequences: When research procedures result in undesirable consequences for the participant that were previously unforeseen, the investigator should immediately employ appropriate measures to correct these consequences, and should redesign the procedures if they are to be included in subsequent studies.
Principle 11. Confidentiality: The investigator should keep in confidence all information obtained about research participants. The participants’ identity should be concealed in written and verbal reports of the results, as well as in informal discussion with students and colleagues. . • Principle 12. Informing participants: Immediately after the data are collected, the investigator should clarify for the research participant any misconceptions that may have arisen. . . • Principle 13.Reporting results: Because the investigator’s words may carry unintended weight with parents and children, caution should be exercised in reporting results, making evaluative statements, or giving advice. • Principle 14.Implications of findings: Investigators should be mindful of the social, political and human implications of their research and should be especially careful in the presentation of findings from the research. This principle, however, in no way denies investigators the right to pursue any area of research or the right to observe proper standards of scientific reporting.
Principle 15. Scientific misconduct: Misconduct is defined as the fabrication or falsification of data, plagiarism, misrepresentation, or other practices that seriously deviate from those that are commonly accepted within the scientific community for proposing, conducting, analyzing, or reporting research. It does not include unintentional errors or honest differences in interpretation of data. The Society . . . will not tolerate the presence of scientific misconduct among its members. It shall be the responsibility of the voting members of Governing Council to reach a decision about the possible expulsion of members found guilty of scientific misconduct. • Principle 16.Personal misconduct: Personal misconduct that results in a criminal conviction of a felony may be sufficient grounds for a member’s expulsion from the Society. . . • Source: As followed by members of the Society for Research in Child Development. Adapted from Winter 1990 SRCD Newsletter. Reprinted by permission.
Theories of Development • Mechanistic theories liken people to machines, such as the mind-as-a-computer model of information-processing approaches. • Learning theories (operant & classical conditioning; social learning theory) • Information-processing theory • Organismic theories take a more “biologic” (nature) view of development, seeing people as whole beings who cannot be understood by decomposing them into their constituent parts. • Piaget’s theory of cognitive development • Psychoanalytic theories of Freud and Erikson
Learning Theories: Classical Conditioning • Behaviorism: Conclusions should be based on observable behavior • Tabula Rasa: Environmental view • Association learning • UCS: built-in, unlearned stimulus • UCR: automatic, unlearned response • CS: causes learned response • CR: learned response
Learning Theories: Operant Conditioning • Probability of behavior based on environmental consequences • Reinforcement • Pleasant consequence • Increases probability • Punishment • Decreases probability • Unpleasant, aversive
Bandura: Social Cognitive Theory • Formerly called social learning theory • Humans think, anticipate, believe, etc. • Cognitive emphasis: observational learning • BoBo doll studies • Model praised or punished • Child learned to imitate rewarded model • Vicarious reinforcement • Reciprocal determinism
Learning Theory: Strengths & Weaknesses • Strengths • Precise and testable theory • Carefully controlled experiments • Practical applications across lifespan • Weaknesses • Inadequate account of lifespan changes • Ignored genetic and maturational processes
Piaget: Cognitive Developmental Theory • Intelligence: Ability to adapt to environment • Constructivism: Understanding based on experience • Interactionist • Both biological maturation and experience required for progress • At each new stage, children think in a qualitatively different way
Cognitive Developmental Theory • Strengths • Well-accepted by developmentalists • Well-researched, mostly supported • Influenced education and parenting • Weaknesses • Ignores motivation and emotion • Stages not universal – esp. last one