Biological Approaches to Personality Flashcards
BIOLOGY & PERSONALITY
- biological approach doesn’t represent cohesive/theoretical approach
- actually approaches collection seeking human personality/beh origin; looks for links between bio/personality
- 3 main areas:
1. EVOLUTIONARY THEORY
2. GENETICS/PERSONALITY
3. BIOLOGICAL THEORIES/BRAIN ANATOMY/BIOCHEM
EVOLUTIONARY THEORY
- personality dispositions arise from evolutionary history/bio makeup/temperament
GENETICS & PERSONALITY
- how much of personality = genetically determined
BIOLOGICAL THEORIES, BRAIN ANATOMY & BIOCHEM
- personality dispositions = complex bio system product
BIOLOGICAL THEORIES, BRAIN ANATOMY & BIOCHEM
- personality dispositions = complex bio system product
EVOLUTIONARY THEORY & PERSONALITY
- bio/environmental/beh/social shaping processes interact w/individual’s genotype; create unique psychological individual’s characteristics
- provides theoretical platform underlying human personality:
1. GENOTYPE
2. PHENOTYPE
GENOTYPE
- individual genetic makeup
- starts unique at birth w/some inbuilt instincts/temperament/pre-wired capacity to learn certain beh kinds
PHENOTYPE
- individual’s observable appearance/beh arising from interaction of genotype w/environment
EVOLUTIONARY THEORY: FOCUS
- common beh patterns > individual aka. human nature
- basic assumptions include:
1. particular behs exist since they were helpful/necessary for survival in human species
2. the more beh helps us survive/reproduce -> ^ likely it’ll occur in subsequent generations - difs observed in human personality understood as consequences of evolution process throwing up personality variations; ^ adaptive survive/procreate
EVOLUTIONARY THEORY & THE BIG FIVE
BUSS (1991)
- evolutionary theory gives framework for understanding central concepts of Big Five via:
1. providing understanding of major human goals
2. describing psychological mechanisms/strategies that exist for reaching goals/overcoming obstacles
3. identifying individual difs in beh that humans use to reach goals/overcome obstacles to them
- Big Five describes main beh dimensions that humans need to develop to adapt to environment/achieve primary survival/reproduction goals
GOSLING & JOHN (1999)
- Big 5 investigated in various animals ie. chimps/cheetahs/hyenas/dogs/cats/pigs
- E/N/A = most studies
- O = large majority (chimps = O; monkeys/hyenas/pigs = curiosity)
- C = ONLY chimps
- core personality dimensions found among animals = similar to personality dimensions compromising Big 5
PADRELL ET AL (2020)
- assessed performance on cognitive task/associations w/motivation/personality range
- findings showed Eysenck’s PEN = good model to describe chimp personality
- authors stress importance of considering personality when interpreting cognitive research results in primates
EVOLUTIONARY THEORY: EVALUATION
- useful heuristic/rules/principles to link biology/environment links to understand common variability (personality dimensions) in human beh
- BUT…
- does not adequately account for individual difs in beh
- many beh/personality phenomena -> humans flexibly responding to circumstances/social structure > evolutionary process
- evolutionary theorists speculating backwards across gens; cannot be directly empirically tested
- nature/society’s goals to ensure survival/reproduction = hard to test
GENETICS & PERSONALITY
- beh geneticists examine degree to which phenotype variation (observable traits) attributed to genotype variation (underlying genetic structure) = trait genetics
- controversial; historical association w/eugenics movement; recent association w/cloning
- 99% human genes = identical; beh genetics concentrates on 1% varying
- basic methodology compares personality similarities/difs between individual pops who are/aren’t genetically related
GENETICS: 3 PRIMARY RESEARCH METHODS
PLOMIN (2004)
- beh geneticists employ 3 primary research methods:
1. FAMILY STUDIES
2. TWIN STUDIES
3. ADOPTION STUDIES
GENETICS: BASIC ASSUMPTION
- if personality traits influenced by genes ->
- traits ^ correlated across closer genetic relatives > ^ distant genetic relatives
- traits ^ correlated across identical monozygotic (MZ) twins > fraternal dizygotic (DZ) twins
- adoption studies = no genetic heritability between adoptive parents/kids
GENETICS: HERITABILITY COEFFICIENT
- computed to reflect genetic influence on traits
- twin studies = heritability estimates for most personality traits = 40-50%
- non-twin/adoption studies = heritability estimates for most traits = 20-30%
- most likely explanation -> gene effects = interactive/multiplicative > addictive
HERITABILITY OF BROAD TRAITS
- numerous large studies taken place/still taking place using data from twin registries in various countries:
PEDERSON ET AL (1988) - twin sample; 95 MZ/220 DZ reared apart
- results suggest strong genetic component for extraversion-introversion
POWER & PLEUSS (2014) - provide heritability estimates of Big 5 personality traits based on common genetic variants
- found for N (15%)/O (20%) BUT not for others
BIG 5 HERITABILITY & BIG 3 PERSONALITY FACTORS
RIEMANN ET AL (1997)
- several studies compared correlations between MZ/DZ twins for 5/3 factor personality models
- if MZ twins = ^ similar > DZ -> heritability evidence
- typically correlations between MZ twins for Big 5 = ^ > correlations for DZ twins
- heritability estimates derived by doubling dif in correlations between MZ/DZ twins
BIG 5 HERITABILITY & BIG 3 PERSONALITY FACTORS: RESULTS
- personality influenced by genetic factors/environmental factors; multiple genes involved BUT none have specifically identified
LOEHLIN & MARTIN (2001) - moderate personality heritability from genetic factors accounting between 20-50% phenotypic variance
GENETICS: HERITABILITY ESTIMATE
- doesn’t indicate extent to which characteristic determined by heritability
- accept overall heritability estimate (.4 personality) DOESN’T mean 40% personality = inherited
- heritability estimate = pop stat; varies w/pop characteristics investigated/data used (ie. twin/adoption data)
GENETICS: HERITABILITY INDEX
- estimate of variance proportion in characteristic measured in particular way in specific pop; can be attributed to genetic variance
- considerable variation around such estimates
GENETICS: EVALUATION
- tells us that genes/environment matter in personality development
- provides window into how early environment does/doesn’t influence later personality
- BUT these estimates considered unreliable; additive model value widely challenged
- shift away from genetics/environment (additive) -> genetics x environment (integrative)
GENETIC VARIANCE ASPECT
- genes interact/suppress other genes
- genetic influence isn’t 1 aspect (aka. additive genetic variance); made of 3 aspects all contributing to total variance:
1. ADDITIVE - total of individual’s genes inherited from parents
2. DOMINANT - dominant/recessive genes
3. EPISTATIC - interactive/genes
ENVIRONMENTS & GENE-ENVIRONMENT INTERACTIONS
- beh genetics provide evidence concerning importance of both genes/environment
LOEHLIN (1992) - when estimating proportion of pop variance of personality trait due to heredity, researchers also estimating prop due to dif environment kinds
- if personality traits show heritability in 30-50% range = same traits show substantial degrees of environmental influence (ie. 50-70%)
PLOMIN & DANIELS (1987)
- environments shared by siblings important in some domains BUT…
- for some personality traits (ie. E/N) it’s unique/non-shared environments experienced by siblings inside/outside family; appear to be critical influence on personality dif
- adulthood personality difs related to extent experiences of siblings in childhoods dif
- findings led to research area considering how non-shared environmental factors develop:
1. IN FAMILY
2. OUTSIDE FAMILY
SHARED ENVIRONMENTS
- consist of environments shared by siblings via growing up in same family; ie:
- socioeconomic family status
- having same parents
- book number in house
- TV/computer availability
- attending same school
NON-SHARED ENVIRONMENTS
- environments not shared by siblings growing up in same family; ie:
- siblings treated dif in same family due to sex/birth order/temperament/school/peer group/friend/activities/sports difs
THE FAMILY ENVIRONMENT
ADLER (1870-1937)
- parents may treat 1 child dif; might reflect dif bio temperaments
- 2 parenting styles influencing personality:
1. pampering (overprotecting; ill equipped for reality)
2. neglect (unprotected/fearful/mistrust)
THE PARENTING STYLES
AUTHORITATIVE
AUTHORITARIAN
PERMISSIVE
NEGLECTFUL
THE DIRECTIONALITY ISSUE
- conventional understanding; influence = bio-directional (parent -> child & vice versa)
- child’s temperament can have impact on parental beh which in turn impacts child development
CHILD-DRIVEN EFFECTS
- difs in children eliciting parenting beh
- positive/negative feedback loop
- can enhance similarities/difs between siblings/confound genetic heritability estimates
POSITIVE FEEDBACK LOOP
- parents reinforce child’s natural beh (ie. shouting/aggression)
NEGATIVE FEEDBACK LOOP
- parents stop child beh according to natural tendencies (ie. disapprove shouting/”calm down”)
WITHIN-FAMILY EFFECTS
- issues when considering genetic heritability
- child/parent effects lead over/under heritability estimations
- parent behs encourage similarity between siblings esp. twins
- similarity estimations in personality caused by genetic heritability = overestimation
- kids’ within-fam situations play important role in shaping personality/estimating genetic heritability
NON-SHARED ENVIRONMENTS: GROUP SOCIALISATION THEORY
HARRIS (1995)
- social identity/categorisation theory
- identity based to some extent on social/in-groups and out-groups we reject
- personalities might reflect group characteristics (ie. adopting group norms)
- social groups form non-shared environment part; influence personality
WITHIN/OUTSIDE-FAMILY EFFECTS
- important influences on personality development
HARRIS (1995) - NOT arguing that beh genetics = wrong/environmental influence = ^ important
- beh geneticists may have oversimplified fam influences -> over/under estimated genetic heritability effects
TEMPERAMENT & PERSONALITY
- temperament = stable individual emotional reactivity difs; observable at birth; determine how baby reacts to situations; express/regulate emotions
- temperaments = broad dispositions > specific personality traits
TEMPERAMENT CHARACTERISTICS
ACTIVITY
DISTRACTABILITY
ADAPTABILITY
EMOTIONALITY
MOOD QUALITY
TEMPERAMENT: 3 MAIN ASPECTS
BUSS & PLOMIN (1984)
- dif temp models BUT generally 3 main aspects agreed:
1. ACTIVITY LEVEL
- some kids = always moving; others = passive
2. SOCIABILITY
- attention/responsiveness/stimulation desire
- part of social interaction
- values interacting w/each other
3. EMOTIONALITY
- some kids become ^ easily/intensely psychologically aroused in situations that may cause distress/anger/fear
TEMPERAMENT: LONGITUDINAL STUDIES
- indicate temperament aspects remain stable over time; influence personality traits development through life
- how broad dispositions/temperaments develop -> stable personality traits depends on complex genetic predispositions/environment interplay
- child’s general emotionality/activity lvl points their developing personality in certain direction; development influenced by kids’ experiences
- kid’s disposition (cuddly/calm/fussy/crying) affects how parents/others react
- BUT how temp -> personality traits = unclear
TEMPERAMENT: EYSENCK’S AROUSAL THEORY
- PEN model
- temperament = emotional/motivational/non-ability related cognitive beh aspects
- original neural model hypothesised human brain = excitatory/inhibitory neural mechanisms
- various experiments disproved it; revision -> placed emphasis on excitation > inhibition
- linked arousal personality theory -> conditionability
TEMPERAMENT: EYSENCK’S SCIENTIFIC PERSONALITY MODEL
- tried to link personality w/temperament/bio aspects of human development
- drew from bio/historical personality typologies/learning theory/factor analysis/experimental studies; developed model coherent w/bio humans
- accepted that environment contributes to overall beh patterns BUT argued PEN = bio based/genetically determined
- scientific model defined PEN; related to hypothetical neural arousal system
EYSENCK: ASCENDING RETICULAR ACTIVATING SYSTEM (ARAS)
- brainstem structure controlling overall cortical arousal
- connects to various brain areas ie. thalamus/hypothalamus/cortex
- ARAS uses 2 circuits to manage arousal lvl:
1. RETICULO-CORTICAL CIRCUIT
2. RETICULO-LIMBIC CIRCUIT
ARAS: RETICULO-CORTICAL CIRCUIT
- controls cortical arousal generated by incoming stimuli
- related to extraversion
ARAS: RETICULO-LIMBIC CIRCUIT
- controls arousal to emotional stimuli
- related to neuroticism
ARAS: INTROVERT
- ARAS shows enhanced reactivity to moderate stimulation
- causes over arousal
- person = introverted as they will avoid stimulation/exciting simulations
ARAS: EXTRAVERT
- ARAS relatively less reactive to moderate stimulation causes under arousal
GALE (1987) - when presented w/moderate stimulation lvls introverts show ^ physiological reactivity > extraverts
- extravert performance on tasks = ^ w/^ stimulation lvls (louder music) BUT…
- introvert task performance = ^ w/lower stimulation lvls (quieter music)
- general arousal theory of criminality = dangerous to have nervous system that needs extra stim
EYSENCK’S BIOLOGICAL PERSONALITY THEORY
- oldest comprehensive attempt at personality model based on bio process
- delineated causal connection between bio brain functions/basic personality dimensions of emotional stability-neuroticism/introversion-extraversion
- enormous research growth over past decades on brain biochem/functions/associations w/personality factors
ARAS: RECENT DEVELOPMENTS
YEO ET AL (2014)
- action of ARAS on cerebral cortex = responsible for consciousness achievement
- 26 patients w/TBI; 13 controls
- detected close relation between consciousness at chronic TBI stage/lower dorsal/upper ARAS injuries in onset TBI patients
- useful during therapeutic strategies development for patients w/impaired consciousness
EYSENCK: INSPIRATIONS
- theories converge on E/impulsivity/novelty seeking/beh approach VS N/harm avoidance/beh inhibition importance
- pushed theories ie:
GRAY (1987) - BAS/BIS Theory (approach/avoid)
CLONINGER (1987) - bio personality model (reward/punishment)
ZUCKERMAN (1984) - alternative 5 factor model
COMPARING BIO MODELS
- links between Cloninger/Eysenck/Gray/Zuckerman:
1. novelty seeking mirrors Eysenck’s E/Gray’s beh approach/Zuckerman’s I
2. harm avoidance mirrors Gray’s beh inhibition/Eysenck’s N
3. Cloninger’s reward dependence mirrors Gray’s beh approach
MATTHEWS & GILLILAND (1999)
- review physiological evidence for Eysenck/Gray’s bio personality theories
- evidence supporting theories BUT weak/inconsistent
- relationships between personality/bio = ^ complex > any single theory
BRAIN ANATOMY & PERSONALITY
- human beh = complex bio system product
- relationship knowledge between brain anatomy/personality comes from studying:
1. brain injury/surgery from imaging techniques ie. PET/fMRI scans
2. chemical beh/personality bases ie. neurotransmitters/hormones
3. dif neurotransmitters/hormones associated w/dif neural subsystems; dif effects on personality/beh
BIOCHEMISTRY & PERSONALITY
- links = cause/effect:
SEROTONIN
CORTISOL
EPINEPHRINE/NOREPINEPHRINE
BIOCHEMISTRY: SEROTONIN
WRIGHT (1995)
- ^/low serotonin lvls associated w/aggression
BIOCHEMISTRY: CORTISOL
- implicated in personality
BORN ET AL (1988) - severe stress/anxiety/depression associated w/^ cortisol lvls BUT result of stress/depression > cause
BIOCHEMISTRY: EPINEPHRINE/NOREPINEPHRINE
- ^ dramatically/suddenly post stress aka. fight VS flight response
ZUCKERMAN ET AL (1987) - ^ norepinephrine associated w/anxiety-proneness/dependency/sociability
- low lvls = disinhibition/impulsivity
BIO/EVOLUTIONARY APPROACHES: STRENGTHS
- bridges personality psych/biology
- helps explain individual difs not easily accounted for by environmental explanations
- identified realistic limitations on “blank slate” personality development model
- empirical research strong emphasis
BIO/EVOLUTIONARY APPROACHES: WEAKNESSES
- social/political undertones may provide justifications for unfair social conditions/prejudices
- from evolutionary/genetic perspective beh change strategies = limitied
- bio approaches to personality study remain fragmented
! SUMMARY !
- bio approach = important to personality understanding; bio/genetic inheritance = building blocks for human personality development
- bio approach won’t supersede other approaches; not gonna show how personality = “caused” by bio mechanisms
- bio approach will show how bio interacts w/social processes to determine what people do/who they are in future
