PERSONALITY

Question 1

BEHAVIOURAL GENETICS

Answer 1

CENTRAL GOALS
= determine % of individual differences in a trait attributable to genes vs. Environment
= determine how genes & environment interact to produce individual differences
= determine where in “environment” environmental effects exist

Genetics account for 90% of variation

Question 2

GENETICS OF PERSONALITY

Answer 2

GENES —> DNA —> BASE PAIRS

Human DNA = 30,000 genes composed of about 3 million base pairs

Roughly 99% of these base pairs are identical for all people -> cannot be the source of ID in personality
= remaining 3 million take different form - genetic mutations or polymorphisms

Question 3

GENETIC INFLUENCES AND HERITABILITY

Answer 3

If genetic differences underlie all variation in the characteristic then heritability = 1.0

Height = 0.9
Weight = 0.7
Maths Ability = 0.4

Virtually every trait studied has substantial heritability [between 0.3 to 0.5] - one third-one half of personality due to genetic influences [PLOMIN, McCLEARN & RUTTER, 1997]

Confirmed by a recent meta-analysis, all traits reported, heritability 49% [POLDERMAN ET AL, 2015]

Question 4

BEHAVIOURAL GENETIC MODELS

Answer 4

FAMILY STUDIES:
= correlate the degree of genetic overlap among family members with the degree of similarity in person trait
= If trait is highly heritable then GREATER RELATEDNESS = GREATER SIMILARITY
= MZ twins - 100% shared genes
= DZ twin, parent, sibling - 50% shared genes
= Grandparent, half-sibling, aunt/uncle - 25% shared genes
= Great grandparent, great aunt/uncle, first cousins - 12.5%

Problem = members of family who share genes usually share environment - confounds genetic/environmental influences and family studies can never be definitive

Familial Risk for Alcohol Dependence [Grucza et al. 2006]
= Multiple measures taken via large family study
= 429 families consisting of 1,111 siblings of pro bands, their mothers and fathers
= Semi-structured assessment for the genetics of alcoholism, family history assessments & novelty seeking
= High NS is magnified in high-risk families, low NS acts as a protective factor against familial alcoholism in these high-risk families

TWIN STUDIES:
Monozygotic = identical
Dizygotic = non-identical

If MZ twins more similar than DZ twins, provides evidence of heritability

Heritability = 2x difference between MZ correlation and DZ correlation

ADOPTION STUDIES:
How adoptive child resembles biological and adoptive parents - nature vs. nurture/genetic vs. environment

Minnesota Twin Study [Bouchard, 1979]

Nancy Segal [1999; 2012]

Separated at birth - reunited twins

SELECTIVE BREEDING -artificial selection [animals and plants], eugenics [humans]

Question 5

SUMMARY OF METHODS

Answer 5

SELECTIVE BREEDING:
+ Can infer heritability if works
- Ethical issues

FAMILY STUDIES:
+ Provides estimates of heritability
- Violate equal environmental assumptions

TWIN STUDIES:
+ Provide both estimates of heritability and environment
- Sometimes violate equal environmental assumptions assumed, may violate assumptions of representativeness

ADOPTION STUDIES:
+ Provide both estimates of heritability and environment, get around the issue of equal environments assumed
- Adopted children might not be representative of population, problem of selective placement

Question 6

EVOLUTIONARY PERSPECTIVE

Answer 6

Evolutionary processes have a major influence on human behaviour

All humans today come from an unbroken line of ancestors who accomplished 2 tasks - survival and reproduction

We carry adaptive mechanisms that led to our ancestors success

Human nature and human personality made up of a collection of evolved mechanisms

Question 7

FIVE FACTOR MODEL

Answer 7

FFM summarises the most important facets of social landscape [Michalski & Shackelford, 2010]

= Conscientiousness may be evaluated to assess who to trust to complete important tasks

= Agreeableness may be evaluated as an index of an individuals willingness to cooperate and to conform to group norms suspending their own concerns

Question 8

SOCIAL BEINGS AND GROUPS

Answer 8

GROUPS
= rewards and problems
= Social situation can be seen as a basis to explain how humans have developed certain personality traits to attain certain goals

Five Factor Evidence
= costs and benefits of the major domains

Question 9

PERSONALITY AND BRAIN FUNCTIONING

Answer 9

Biological processes which underlie personality

Genes do not directly affect behavioural dispositions - do so indirectly by influencing brain development, brain structure and brain chemistry

Focus on major personality dimensions outlined by trait theories

Question 10

PHYSIOLOGICAL MEASURES

Answer 10

ELECTRODERMAL ACTIVITY

CARDIOVASCULAR ACTIVITY

BRAIN ELECTRICAL ACTIVITY

OTHER MEASURES:

• Biochemical analysis
• Hormones

Question 11

DATA TO ASSESS BIOLOGICAL PROCESSES

Answer 11

Differences in the reactivity and regulation of Autonomic Nervous System [ANS]:
= Sympathetic system - fight or flight
= Parasympathetic system - relaxation, digestion, down-regulation

Localisation of Function in Brain Hemispheres and structures:
= Do inhibited children show greater activation in the amygdala when faced with unfamiliar situation

Neurotransmitters:
= secreted by neurons directly into the synapses
= immediate action

Hormones:
= Secreted by neurons and endocrine cells into the bloodstream
= Fight-or-flight hormones [cortisol]
= Social affiliation hormones [oxytocin]

Question 12

TRAIT THEORIES - HANS EYSENCK

Answer 12

Psychometric measures of personality - EPQ

Biological Basis of Personality [1963]

Supertraits [PEN Theory, 1967]
= Psychoticism
= Neuroticism
= Extraversion

Question 13

ASCENDING RETICULAR ACTIVATING SYSTEM [ARAS]

Answer 13

Brain area [within the brain stem] responsible for regulating arousal [and sleep-wake transitions]

Through 2 circuits:
= Reticulo-cortical circuit controls the cortical arousal generated by incoming stimuli
= Reticulo-limbic circuit controls arousal to emotional stimuli

Strength of Eysenck’s Theory
= Using the concept of ‘arousal’ as a central variable that allows personality to be linked to a number of responses

Extraverts’ arousal:
= typically low
= prefer more stimulating environments to increase arousal

Introverts’ arousal:
= typically high
= prefer less stimulating environments to reduce arousal

LEMON JUICE EXPERIMENT [Eysenck and Eysenck, 1960s]
= Test the cortical arousal theory of extraversion-introversion
= Who produces more saliva and why

REINFORCEMENT SENSITIVITY THEORY [Gray, 1993]
= Approach and avoidance sensitivity
= Two basic brain systems that control behaviour and emotions - Behavioural Activation System [BAS] and Behavioural Inhibition System [BIS]
= Individual differences in personality traits reflect the variation in sensitivity of BIS & BAS

MEASURING BIS AND BAS
= Gray didn’t come up with one, others have since
= McAndrew and Steele [1991] - measure of BIS sensitivity
= Carver and White [1994] - most reliable and valid, revised Gray’s theory, the ‘Big Two’

Question 14

SENSATION SEEKING

Answer 14

A trait with a specific biological basis

The sensation seeking trait (SS):
= the seeking of varied, novel, complex and intense sensations and experiences

SS Scale
= Thrill and adventure seeking - I sometimes do things that are a little frightening
= Experience seeking - I like to have new and exciting experiences
= Disinhibition - almost everything enjoyable is illegal or immoral
= Boredom susceptibility - I get bored seeing the same old faces

ZUCKERMAN - Biosocial Basis of Sensation Seeking
= Genetic contributions of SS have been assessed via twin studies - 58% of the variance in SS was found to be heritable [Zuckerman, 1991]
= Low Monoamine Oxidase [MAO] associated with high SS