Development and Nature vs. Nurture Genes vs. the Environment

Studying Development – Developmental psychology is the study of age-related changes in behavior and mental processes from conception to death. – Philosopher John Locke argued that our minds are a “blank slate” when we are born and that development occurs through learning and personal experience. – Others emphasize the role of a sequence of genetically programmed processes of growth and development that occur over time. Also there are important critical periods that occur. (A specific time of great sensitivity to age-related learning that shapes the capacity for future cognitive development.)

Con’t. – Psychologists use either a continuity or discontinuity approach when studying development. The continuity approach argues that development is a continuous process, at a gradual pace. Discontinuity argues that there are distinct stages or critical periods where development occurs. (Stage theories and theorists) Longitudinal and Cross sectional methods are often used to study development.

Con’t. Behavior Geneticists study the impact of genetics and environmental influences on our behavior. – Chromosomes are made of DNA, which have smaller segments called genes. Human genome researches (studying the process of making an organism) have found… – We share 96% of our DNA sequence with chimpanzees. – We have similar DNA codes with eachother.. » Genetically speaking, we are about 99.9% the same. » Slight person-to-person variations make us unique. Traits influenced by many genes

Con’t. Genes: – We inherit one set of 23 chromosomes from each parent. The two sets form pairs that contain alternate genes for the same traits. Sometimes, one is dominant and overrides the recessive gene.

Studying Development: Twin Studies To understand the influences of environment and identity, twin studies are used. Identical Twins (monozygotic) are developed from a single fertilized egg that splits in two with same genetic code (genetically identical) – They don’t always have the same number of copies of those genes… – Most share a placenta during prenatal development, one of every 3 sets have 2 separate placentas…one may get slightly better nourishment due to this. Fraternal Twins (dizygotic) develop from separate fertilized eggs and are no more similar than ordinary brothers and sisters. Studies of twins indicate that identical twins are much more behaviorally similar than fraternal twins.

Biological vs. Adoption Studies Studies showed that adoptees are more similar personalities to their biological parents than to their adoptive ones. – However, they do influence attitudes, values, manners, etc.

Temperaments and Heredity A person’s characteristic emotional reactivity and intensity…an individual’s characteristic manner of behavior. Researchers believe it has strong genetic links. Parenting styles, social interaction and ability to adapt to different social situations can modify a child’s temperament. – General temperament persists throughout childhood. (see examples on 140)

Heritability Estimate of how much variation among individuals can be attributed to their differing genes. Environment plays a factor…(see examples on 140)

Conclusions… Conclusions re: Nature vs. Nurture Genes and the environment interact with each other.

One more thing… Molecular Genetics: Subfield of biology that studies the molecular structure and function of genes – Genetic testing – Ethical Considerations