Nature & Nurture of Behavior

NATURE & NURTURE OF BEHAVIOR

I. genetics – nature

A. every human cell nucleus contains chromosomes- 46 total: 23rd pair = gender; X from mom/X (girl) or Y (boy) from dad

1. DNA – coils that make up chromosomes

a. genes–parts of DNA molecules w/ instructions to make proteins necessary for physical development

1. nucleotides – biochemicals that form genes

II. evolutionary psychology focuses on natural selection (certain traits, over time, prevail) – differences may grab our attention, but biological similarities are astounding! (99.95%)

III. mutations – random errors in gene replication

IV. sexuality – which gender has stronger sex drive? – gender differences in attitudes extend to differences in behavior – women are more relational, men are more recreational

A. men can reproduce more often and more widely – youthfulness is important b/c probability of babies is higher

B. women must choose wisely, often focusing on success, kindness, & generosity b/c need help raising/protecting family

V. critics of evolutionary psychology say they start with an effect or a behavior and work backwards to explain it; culture plays a greater role in behavior (ever-changing, NOT static)

VI. behavior geneticists are more concerned w/ differences

A. genes AND environment

B. identical twins – single egg/fraternal twins – two eggs

C. moderate genetic influence on certain attitudes and certain abilities– identical twins are far more similar

D. twin studies & adoption studies are best research tools

E. are adopted children more like their adoptive parents or biological parents?

1. people who grow up together are more dissimilar than many think - not that much alike personality-wise!

2. values, attitudes, manners, religion & politics are more similar than not (from environment)

VII. temperament – broad personality disposition & emotional reactivity (neuroticism) – newborns tend to develop into similar adults (stability); thought to be biologically rooted or inherited - nature

VIII. heritability – the proportion of a particular trait (intelligence, happiness, temperament) that can be attributed to genes v. environment (i.e. identical twins raised in very different environments have similar IQ  high heritability)

IX. parental influence on personality is more limited than once believed – pre-natal environment, brain development, peer influence & culture are strong influences

A. placenta helps provide nutrients & block teratogens

B. early learning – repeated experiences result in stronger and more numerous neural connections (activate & preserve connections – use it or lose it!)

C. peer influence – naturally we will work with, interact with, and mate with our peers so influence is strong (i.e. accent)

D. culture – behaviors, ideas, attitudes & traditions shared by a large group (i.e. independent culture v. collectivist culture)

1. norms – the rules shared by the group

2. memes – self-replicating ideas, fashions, innovations, etc. (cultural mutations)