Social Development Chapter 3 Biological Foundations: Roots in Neurons and Genes

Neurological Bases of Social Development: Brain Growth and Development Motor cortex – starting at birth Visual Cortex – 3 months Auditory Cortex – months Prefrontal Cortex – 3-5 years Limbic System (i.e., emotions) - Puberty Prefrontal Cortex - Puberty

Neurological Bases of Social Development: Brain Growth and Development Motor cortex  Birth to 2 months – shift from reflexes to voluntary control of movement  8 months – ability to crawl and search for hidden objects  12 months – walking

Neurological Bases of Social Development: Brain Growth and Development Visual cortex  3 months – look longer at facelike vs. non-facelike stimuli Auditory cortex  18 and 24 months – language development Prefrontal cortex  3-5 years – development of executive processes

Executive Processes: Developmental Trajectory

Neurological Bases of Social Development: Brain Growth and Development Limbic System / Amygdala  Puberty - changes in social and emotional processing Prefrontal Cortex  Puberty to early adulthood – improvements in executive function © Barbara Smaller/CondeNast Publications/

Neurological Bases of Social Development: Hemispheric Specialization Cerebral hemispheres - The two halves of the brain’s cerebrum, left and right  Anatomically different  Control different functions Hemispheric lateralization (frontal assyemtry) - The process by which each half of the brain becomes specialized for certain functions

Left Frontal Lobe Right Frontal Lobe Avoid! (Davidson 2002; Harmon-Jones & Allen, 1998 Zuckerman, 2005) Extraversion Approach! Visual Spatial Info: Nonspeech sounds Perception of faces Joy, interest, anger Language Processing Fear, disgust, distress Neuroticism

Hemispheric Lateralization Has a genetic component Begins early in life, but because not complete; younger children have greater brain plasticity Even adults have plasticity

Neurological Bases of Social Development: Mirror Neurons and the Social Brain Mirror neuron - A nerve cell that fires both when a person acts and when a person observes the same action performed by someone else, as if the observer himself or herself were acting  When observing another person’s behavior, our motor cortex activates  Important for observation learning (think Bandura!)  Important for empathy and perspective-taking Mirror Neuron Hypothesis of Autism

Focuses on the relative contributions of heredity and environment to individual differences in human behavior using statistical estimation

Common BG Designs Twin Design Are identical twins reared together more similar to each other on various attributes than pairs of fraternal twins reared together? Adoption design Are adopted children more similar to their adopted parents (whose environment they share) or their biological parents (whose genes they share)?

Heritability The amount of variability in a trait that is attributable to hereditary factors Population estimates (not individuals) Particular population and particular environmental influences

Shared Environment Experiences that individuals living in the same home environment share and that make them more similar to each other Parent’s modeling moral, religious, & political views Also called “common environment”

Nonshared Environment Experiences that are unique to the individual Not shared by other members of their family and make family members different from each other Also called “unique environment”

Measuring Heritability Heritability  h 2 = 2 (r MZ – r DZ ) Shared/Common Environmental Effects  c 2 = r MZ – h 2 Nonshared/Unique Environmental Effects  e 2 = 1 – r MZ To Check Answers: h 2 + c 2 + e 2 = 1

A researcher is interested in determining the contribution of genes and environment to Agreeableness (A). She obtains 500 pairs of identical twins and 500 pairs of fraternal twins. The twins complete self-report measures of the HEXACO scale. She determines that the personality similarity correlation between the identical twins is.98. The personality similarity correlation between the fraternal twins is.63. Calculate the following: 1.Heritability of Agreeableness 2.Shared Environmental Effect 3.Unique Environmental Effect

Genotype x Environment Correlations

Passive G/E Correlation  Rearing environments that biological parents provide are influenced by parents’ own genes

Parents’ Genotype Child’s rearing environment Child’s Genotype

Genotype x Environment Correlations Passive G/E Correlation  Rearing environments that biological parents provide are influenced by parents’ own genes Evocative G/E Correlation  Our heritable attributes affect others’ behavior toward us and thus influence the social environment

Child’s Genotype Behavior of others toward child Environ. Influence on child’s development

Genotype x Environment Correlations Passive G/E Correlation  Rearing environments that biological parents provide are influenced by parents’ own genes Evocative G/E Correlation  Our heritable attributes affect others’ behavior toward us and thus influence the social environment Active G/E Correlation  Genotypes influence the types of environments that we prefer and seek out

Child’s Genotype Preference and selection of environment Environ. Influence on child’s development

Identify the Correlation! Passive G/E Correlation Evocative G/E Correlation Active G/E Correlation 26

Genetics and Social Development: Models of Genetic Influence Percentage of individuals meeting diagnostic criteria for depression at age 26, as a function of depressive genotype and number of stressful life events between ages 21 and 26 Caspi, A., Sugden, K., Moffitt, T. E., Taylor, A., Craig, I. W., Harrington, H.,... Poulton, R. (2003). Influence of life stress on depression: Moderation by a polymorphism in the 5-HTT gene. Science, 301, 386–389. Reprinted with permission from AAAS

G/E Correlations across Development Active Passive

Figure 3.3 (p. 83) Relative influence of passive, evocative, and active (niche-picking) genotype/ environment interactions as a function of age.

Chapter 3 Overview Biologically preprogrammed behaviors (e.g., synchrony, senses) Importance of certain brain regions for development Measuring heritability for a sample 3 types of G-E correlations