BIOLOGICAL PSYCHOLOGY NATURE VS. NURTURE

Transcription

1 BIOLOGICAL PSYCHOLOGY NATURE VS. NURTURE

2 Founder of the Trait Theory Predispositions to respond, in a same or similar manner, to different stimuli After meeting Freud, Allport felt there was too much emphasis on inner drives Gordon Allport

3 Trait Theories of Personality Personalities described by main characteristics (traits) Traits (honesty, laziness, ambition, outgoing) thought to be stable throughout life

4 Key Ideas of Trait Theory We are psychophysical beings Mind and body function together Personality develops from both mental and biological influence Each person is unique Everything is a characteristic of us and no one else Heredity (genetics) provides raw materials Environment shapes, expands, or limits heredity (raw materials)

5 Key Ideas of Trait Theory In other words: individual combination of genes (except for identical twins) + the environment = personality Two personalities Childhood (more biological) Adulthood (more environmental) Childhood personality does not determine adult personality!

6 Other Trait Theorists

7 Dimensions of personality 1. Extraversion vs. introversion (E) 2. Neuroticisms vs. emotional stability (N) 3. Psychoticism vs. impulse control (P) Predisposed to each Collectively makes up personality Hans Eyesenck

8 Extraversion vs. introversion (E) Extraverts Lower level of cortical (brain) arousal Seeks stimulation Introverts Higher level of cortical arousal Shies away from stimuli Hans Eyesenck

9 Neurotic vs. emotional stability (N) Neurotic Greater brain activity in sympathetic branch of autonomic nervous system Alarm system fight, flight, or freeze Overreacts to even mild stress Emotional stability More subdued responses More level headed Hans Eyesenck

10 Psychoticism vs. Impulse control (P) Psychoticism Aggressive Anti-social Tough minded Cold Ego-centric Cruel, hostile, insensitive Men tend to score higher (hormonal) Impulse control Can channel aggression into appropriate activity Hans Eyesenck

11 Heredity plays greater role than environment Descriptors of E Sociable, lively, active, assertive, sensation seeking, carefree, dominant, venturesome Descriptors of N Anxious, depressed, guilt feelings, low self-esteem, tense, irrational, shy, moody Descriptors of P Aggressive, cold, egocentric, impersonal, impulsive, anti-social, creative, toughminded Hans Eyesenck

12 Robert McCrae and Paul Costa Big Five factors of personality Stability Extraversion Openness Agreeableness Conscientiousness

13 Stability (calm or anxious, secure or insecure, self-satisfied or self-pitying) Extraversion (sociable or retiring, fun-loving or sober, affectionate or reserved) Openness (imaginative or practical, variety or routine, independent or conforming) Agreeableness (soft-hearted or ruthless, trusting or suspicious, helpful or uncooperative) Conscientiousness (organized or disorganized, careful or careless, disciplined or impulsive) The Big Five

14 According to Big Five trait theory: Traits are stable over time Can be attributed to genetics Describes personality equally across different cultures Predicts other attributes The Big Five

15 Correlations with the Big Five: Which behaviors correlate? Protested injustice - Emotionally stable, open Fell in love at first sight - Extraverted Have not been in therapy - Emotionally stable Been in therapy - Open Thrown a large party - Extraverted Kept a diary - Open Listen to music by self in dark - Open

16 Correlations with the Big Five: Which behaviors correlate? Read fewer than 12 books per year - Extraverted Never cheated on a test - Conscientious Never pulled all-nighter to finish assignment - Conscientious Not likely to become addicted to Internet -Extraverted Dated a person of a different race - Open Written a poem spontaneously - Open

17 Arnold Buss and Robert Plomin Temperament Building blocks of personality Everyone has levels of all three Primarily biological; can be adapted by environment

18 First Temperament Emotionality Level of excitability for unpleasant feelings Sensitive to any emotion unemotional Arnold Buss and Robert Plomin

19 Second Temperament Activity Physical energy and vigor Constant movement unmoving Arnold Buss and Robert Plomin

20 Third Temperament Sociability Preference for contact/interaction with others Want to be around others Don t like to be around others Arnold Buss and Robert Plomin

21 Reflection: Looking at the Big Five and Three Temperaments, which ones do you see having the greatest impact on your life? Assessing Our Traits

22 Untangling Nature and Nurture Behavior Genetics: the study of the interaction of genes and environment on behavior

23 Nature = role genes have on a trait Nurture = role life experience has on trait Eysneck, McCrae and Costa, and Buss and Plomin all used twin studies in research Nature vs. Nurture

24 Biological Theories of Personality What % of the variation in a population is attributable to genes? - heritability Not sure; BUT temperaments do seem to be stable from infants to old age.

25 Percentage of trait variation in a group that can be attributed to genetic differences (can be inherited) In other words, what role do genetics play? 0% means genes play no role 100% means genes play entire role Depends on the population Heritability

26 Heritability Sara is very outgoing and agreeable Suzy is timid and nonconforming If this pair of IDENTICAL twins is my population, what percent of the personality differences is attributable to genetic differences between them? The heritability is 0%.

27 Joe and Hank are not related. At birth, both were placed in identical environments that were maintained identical until they were 10 years old. At 10, Joe is outgoing and friendly. At 10, Hank is withdrawn and shy. In this (very small) population, what is the heritability of their personality traits? In other words, what percentage of the difference is attributable to genes? Heritability 100%

28 Trait Population Heritability Creativity adolescents 25% Extraversion adults 30-50% Autism general 90-95% Depression general 40-55% Sleep quality general 35% TV viewing 3-5 year olds 10-45% Religious beliefs general 0% Religious conservatism women 40% Divorce general 55% Height women 92% How heritable is that trait? The Stanton Peele Addiction Website

29 Twin Studies Identical Twins vs. Fraternal Twins Same genes, Different genes, Same environment Same environment Therefore, greater differences between the two groups indicate greater heritability ( Nature ). The trait might appear to have a large genetic component.

30 % increase Twin Studies 60% 50% 40% 30% 20% 10% 0% Increased risk of schizophrenia if twin develops disease Fraternal twins Identical twins Criticism: 1) Do fraternal twins really have equally similar environments to identical twins? Differences in looks or inborn temperament may cause people to treat you differently. 2) Identical twins may share a placenta but fraternal twins do not. Thus, we can t eliminate prenatal environments as the cause of the differences between the two groups.

31 Twin Studies Identical Twins Reared Together v. Identical Twins Reared Apart Same genes, Same environment Same genes, Different environment Greater difference between these two groups indicates greater role of the environment ( nurture ).

32 Correlation Twin Studies Similarity of IQ Test Scores in Twins Identical twins reared together Identical twins reared apart Criticisms: 1) Adoption agencies try to place twins in similar families so the variation in environment may be small, and 2) There is a very limited sample.

33 Is child more like adoptive parents or biological parents? Adoptive Parents - Nurture Adoption Studies Biological Parents - Nature

34 Correlation Coefficien Correlation Coefficient Adoption Studies Similarity of Values Between Adopted Children and their Parents Biological parents Adoptive parents Similarity of Temperament Between Adopted Children and their Parents Note: Two related siblings that grow up in the same family are strikingly different in personality (as I m sure many of you can attest to) Biological parents Adoptive parents

35 Nature? Nurture? Both? Twins? Genetic engineering? Genetic engineering? Examples of theories?

36 What is your opinion of the nature vs. nurture theory of psychology? In other words, do you believe nature is dominant, nurture is dominant, or it s a combination of both? Please explain your answer! Reflection