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Biology & Personality

Biology & Personality. Phineas Gage video. Early evidence of brain & temperament Brain injury changed disposition Role of body & brain in consistencies of behavior? Extraverted bodies? Emotionally (un)stable brains?. Outline. Temperament Evolution and personality Behavioral genetics

charlesmelvin
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Biology & Personality

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  1. Biology & Personality

  2. Phineas Gage video • Early evidence of brain & temperament • Brain injury changed disposition • Role of body & brain in consistencies of behavior? • Extraverted bodies? • Emotionally (un)stable brains?

  3. Outline • Temperament • Evolution and personality • Behavioral genetics • Brain and temperament

  4. Temperament • Individual differences in affective response • Inherited • Biologically based • Evidence from birth & stable throughout life • NOT traits but related • Traits not stable from birth & less pervasive influence

  5. Temperament • Early views linked T w/ body features • Gall & phrenology • Kretschmer, Sheldon & body types • Inherited body determines T • Direction of effect problem • Recent work finds that endo NOT jolly

  6. Temperament: Recent Research • New York Longitudinal Study (Thomas & Chess, 1977) • Kids followed from birth (1950) - adolescence • Parental reports revealed easy, difficult, & slow-to-warm-up babies • Associated w/ later adjustment

  7. Temperament: Recent Research • Kagan (1999): Inhibited v. uninhibited kids • Laboratory observations of 4 month olds revealed high & low reactivity • Stability of T at 4/8 years old • Change also due to parental influence

  8. Temperament: Recent Research • In sum temperament construct supported • Link between biology & personality • Reciprocally causal • Temperaments linked w/ Big-5 (guide trait development) • Emotionality (~N) • Activity (~E) • Sociability (~E)

  9. Jealousy • On a clean sheet of paper answer this Q: • What would bother you more: Your boy/girl friend (spouse) having sex with someone else or developing emotional feelings for someone else? • Sexual or emotional infidelity? • What is your gender?

  10. Evolutionary Theory • Characteristics associated w/ survival selected • Ultimate causes of current behavior tendencies • Evolved psychological mechanisms (specific) • Nature of human nature (e.g., social) • Individual differences • Directional v. stabilizing selection • Niches

  11. Activity 9: Gender Differences • Provide a critical analysis of the research examining evolutionary predictions regarding gender differences in mate preferences & jealousy. • Does the evidence support these claims? • Can you think of any alternative explanations? • PLEASE TURN THIS IN AFTER CLASS!

  12. Gender Differences • Problems w/ evidence for evolutionary account • 1. Failures to replicate • Some studies find most men choose emotional infidelity • No gender differences in physiology • 2. All forced choice methodology • No gender difference w other methods

  13. Gender Differences • Harris (2002) • Forced choice • M > W on sexual

  14. Gender Differences • Harris (2002) • Recalled episode of infidelity • No gender effects • Both more bothered by emotional

  15. Gender Differences • 3. Cultural/social theories: Similar predictions • Social Exchange Theory • Men control resources, women control sex • Women give sex to men in exchange for resources • Women most upset about losing resources (love = shifting loyalties) & choose resource-rich mate • Men most upset about losing sex & choose sexy mate

  16. Day 2

  17. Behavioral Genetics • Examine contribution of nature & nurture • Twin & adoption studies • Heritability coefficient (h2) • Findings: h2s ~ .40 • Specific to population • Not fate • Not single genes “Bummer of a Birthmark Hal”

  18. Shared & Non-Shared Environment • Variability in characteristics in population • 40% genetic • 40% environment (+ 20% error) • Shared (same family, house, etc.): 5% • Non-shared (unique experiences, including perceived even w/in same family): 35%

  19. Shared & Non-Shared Environment • Similar environments have little impact • Similar experiences do not -> personalities more alike • Genes make us similar • Non-shared environment makes us different

  20. Reaction Paper 7: Rearing Influences • How much variability in personality is due to shared environmental influences? Does this suggest that rearing practices & parents are not important in personality development? Was Dan Quail wrong in saying single parent homes are bad for the children?

  21. Neuroscience & Personality • Where in the brain is personality? • Specific areas & systems show individual differences

  22. Amygdala • Motivation & emotion • Damage impairs NA Rs • Arousability linked w/ T • Metabolically linked w/ N

  23. Amygdala • Neurotics have rapid amygdalar metabolism • Impair NA repair, decay • Explain NA of neurotics? Irwin et al (2000)

  24. Ascending Reticular Activation Formation (ARAS) • Located w/in brain stem & controls arousal • Individual differences in reactivity • Extraversion due to reactivity of ARAS • Baseline higher among I • Response to stimulation stronger among I

  25. Extraversion and ARAS arousal

  26. Optimal Arousal • Comfortable functioning • Es under-aroused & should prefer high stimulation activities • Is over-aroused & should prefer low stimulation activities • Stimulus shy (I) or Stimulus hungry (E)

  27. Evidence • Task choice • E choose higher stimulating behavior than I • Physiological arousal • I > E for given level of stimulation • Task performance • Is do better at monotonous jobs (air traffic) & moderate levels of stimulation • Es do better at fast paced jobs & higher levels of stimulation

  28. Approach & Inhibition Systems • 2 Brain system involved with: • Approach behaviors & positive emotions • Inhibit behaviors & negative emotions • Key are individual differences in the reactivity of these brain systems

  29. Behavioral Approach System (BAS) • Structures in left Pre Frontal Cortex (PFC) • Cause approach behavior (GO!) during incentives • Controls positive emotions • Individual differences in reactivity (hi lo) • Associated w/ E & uninhibited T

  30. Behavioral Inhibition System (BIS) • Structures in right Pre Frontal Cortex (PFC) • Cause avoidance/inhibitory behavior (Stop/Reverse!) • Activated during punishment/danger/threat • Controls negative emotions regarding punishment • Individual differences in reactivity (hi lo) • Associated w/ N & inhibited T

  31. BAS/BIS Measurement • EEG activity • High baseline (left or right PFC) & strong response to positive or negative stimuli • Self-Report Measures • Reward or Punishment sensitivities, seek/avoid • When I get something I want I feel excited & energized • Criticism or scolding hurts me quite a bit • Correlated w/ PFC activity

  32. BAS & BIS BAS • Independent dimensions • Individual differences on both • All combinations possible • These combos are key for understanding personality BIS

  33. Neurotransmitters • BAS, PE associated w/ dopamine • Genes producing dopamine & dopamine reactivity linked to self-reported BAS • BIS, NE associated w/ serotonin • Genetic evidence mixed

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