Lecture 6 - Personality: Genetic, neurobiological and socio-cultural perspectives Flashcards
Riemann et al., (1997) twin study on personality traits
Riemann et al. (1997) compared >1,000 monozygotic and dizygotic twins on the Big Five. Correlations between them were as follows:
MZ twins:
extraversion - 0.56
neuroticism - 0.53
agreeableness - 0.42
conscientiousness - 0.54
openness- 0.54
DZ twins:
extraversion - 0.28
neuroticism - 0.13
agreeableness - 0.19
conscientiousness - 0.18
openness- 0.35
higher correlations between MZ twins
what is Flaconer’s formula used for?
to calculate heritability correlations
Falconer’s formula to calculate heritability
h^2 = 2(r mz - r dz)
h = heritability
r mz and r dz are the correlations
adoption studies on personality
Loehlin et al. (1985) found larger correlations between children and biological parents (.16–.34) than between children and adoptive parents (.02–.12) on a number of traits
- Hershberger et al. (1995) found that identical twins reared apart did NOT show lower correlations on extraversion & neuroticism than identical twins reared together – but did on openness
- Bergeman et al. (1993) concluded that genetic influence was “substantial” for openness (40%) and conscientiousness (29%), but was weak for agreeableness (12%) and that “there was little evidence of shared rearing environment”
(more similar in personality to biological parents rather than adoptive parents)
issues with heritability estimates
- Heritability is concerned about genetic variation in a population
- The additive assumption in estimating heritability versus the effects of environment is problematic
- There are 3 types of genetic actions and their respective genetic
variance are difficult to partition (Huang & Mackay, 2016):
– Additive genetic actions – different genes work independently
– Dominant genetic actions – dominant genes suppress expression of
recessive genes
– Epistatic genetic actions – certain genes determine whether other genes
will be expressed or suppressed
additive genetic actions
– Additive genetic actions – different genes work independently
dominant genetic actions
– Dominant genetic actions – dominant genes suppress expression of
recessive genes
epistatic genetic actions
– Epistatic genetic actions – certain genes determine whether other genes
will be expressed or suppressed
Eysenck’s biological model of personality (explain)
Eysenck (1967) suggested that the human brain has two neural mechanisms:
– excitatory mechanism – keeps the individual alert, active and aroused
– inhibitory mechanism – causes inactivity and low energy
- These two mechanisms are regulated by two independent circuits of arousal
what does Eysenck propose extraversion is linked to?
linked to the arousal circuit responding to incoming stimuli (known as reticulo-cortical circuit)
- According to Eysenck, while the introverts have over-aroused circuits, the extraverts have under-aroused circuits
(incoming circuits under-aroused so they are constantly seeking for more arousal extraverts (opposite for introverts)
what does Eysenck propose neuroticism is linked to?
linked to the arousal circuit responding to emotional stimuli (known as reticulo-limbic circuit)
- In stressful situations, the neurotics would be more emotionally aroused while emotionally stable individuals are less aroused
(neurotics try to avoid further arousal)
empirical support for Eysenck’s proposals on extraversion, neuroticism and arousal
- Geen (1984) asked introverts and extraverts to choose noise levels of music to listen to while doing a difficult and boring task
- As predicted, extraverts chose higher levels of music than did introverts. Both groups completed the task well under the chosen conditions, but not in the reverse conditions
- For neuroticism, in a neuroimaging study, Kehoeetal. (2012) found that the link between neuroticism and arousal is more complicated than Eysenck proposed
- While neuroticism is linked to increased reactivity to emotional arousal, it is also linked to reduced reactivity to positive stimuli
Explain Gray’s reinforcement sensitivity theory (RST) (1970)
- personality based on interaction between 3 basic systems in brain
- behavioural approach system (BAS)
- behavioural inhibition system (BIS)
- fight/flight/freeze system (FFFS)
what is the behavioural approach system (BAS) in Gray’s RST?
comprises motivations to approach and causes the individual to be sensitive to potential rewards and to seek those rewards
outgoing to seek rewards
what is the behavioural inhibition system (BIS) in Gray’s RST?
comprises motivations to avoid based on conditioned sensitivity to potential punishment or non- rewarding stimuli
stay away from conditions
what is the fight/flight/freeze system (FFFS) in Gray’s RST?
a mechanism that responds to threat by a tendency to fight, take flight or freeze
knowledge of NS
relationship between Gray’s and Eysenck’s models
- Gray (1990) proposed that sensitivity to reward and punishment are two independent dimensions, and
- that Eysenck’s E and N dimensions should be rotated about 30° to form more causally efficient axes of ‘punishment sensitivity’ (anxiety) and ‘reward sensitivity’ (impulsivity)
- This theory explains why introverts are more aroused: they are punishment sensitive (punishment is more arousing than reward)
- Likewise, neurotics are punishment sensitive (hence aroused), at the same time reward sensitive (hence impulsive)
Cloninger’s psychobiological model (1993)
- 4 dimensions of temperament and 3 dimension of character
- The temperament dimensions are independently heritable, manifest early in life, and involve individual differences in associative learning in response to novelty, danger or punishment, and reward;
- whereas the character dimensions mature in adulthood and influence personal and social effectiveness by insight learning about self-concepts
(picks up on Gray’s punishment and reward ideas. differentiated between temperament and character)
4 temperaments in Cloninger’s psychobiological model of personality
novelty seeking
harm avoidance
reward dependence
persistence
Thought to be organised as independent brain systems, and linked to neurotransmitters that are responsible for the activation and inhibition of our behaviour and responses to rewards and punishments
what are characters based on in Cloninger’s psychobiological model?
differences in self-concepts which vary according to the extent to which a person identifies the self as:
- an autonomous individual
- an integral part of humanity
- an integral part of the universe as a whole
what are the 3 character dimensions in Cloninger’s psychobiological model?
self-directedness
cooperativeness
self-transcendence
problems with psychobiological theories
- inadequate empirical support, with only some parts of the theories supported by research evidence
- For instance, the relation between neuroticism and arousal was much less well supported than that between extraversion and arousal
- Stewart et al. (2004) found that items measuring Cloninger’s traits more closely resemble FFM and Eysenck’s model than the original 7- factor model
- these theories may have oversimplified biological processes in their theory
what have fMRI studies found about extraversion in terms of neural correlates?
- found extraversion associated with neural activation in response to pleasant stimuli in dopaminergic neurons and other brain regions in the reward network (right above brainstem)
- Effects of manipulating dopamine pharmacologically are moderated by extraversion, such that extraverts responded with more positive affect in response to stimuli previously paired with dopamine drug experience
- Extraversion positively related to volume of medial OFC (mOFC; a cortical region involved in monitoring the reward value of stimuli), as well as glucose metabolism in mOFC while at rest (to do with reward processing)
neural correlates of neuroticism
- most frequently linked to neuroticism is the amygdala, which modulates attention and arouses the sympathetic nervous system in response to danger signal
- also linked to the medial prefrontal cortex (mPFC) and the dorsolateral prefrontal cortex (dlPFC), both thought to down-regulates negative emotions
- All of the systems implicated in neuroticism are modulated by serotonin, and pharmacologically modulating serotonin level was found to result in decline in neuroticism. However, the actual relationship between serotonin and neuroticism seems complex
neural correlates of openness
- linked to individual differences in dopamine function
- Research has found that – whereas extraversion is associated with encoding of stimulus value, and functional connectivity between dopaminergic neurons and the nucleus accumbens and caudate nucleus – openness correlated with encoding of stimulus salience, and functional connectivity between dopaminergic neurons and dlPFC
- openness is linked to the default network, is a set of brain regions that are more active during rest and is thought to be responsible for self-generate thoughts (thinking and reflecting on oneself)
neural correlates of conscientiousness
- Structural MRI studies have found positive associations of conscientiousness with the volume of regions in dlPFC
- It can be attributed to the fact that dlPFC is one of the regions of the goal priority network, which is thought to play a role in determining the priority of goals and reorienting attention away from distractors and toward goal-relevant stimuli
- And conscientiousness was positively associated with functional connectivity in this goal priority network
- Conscientiousness may be linked to serotonin, but extant evidence is inconclusive
neural correlates of agreeableness
- research comes from the study of empathy, which involves mentalizing (understanding others’ perspectives) and mirroring (feeling others’ emotions)
- Mentalizing was found to primarily involve the default network, whereas mirroring for emotion primarily involves the insula and regions of midcingulate cortex.
- In an fMRI study, agreeable participants showed increased neural activities in the reward circuits knowing that a charity received a payment compared with that they received payment themselves
- Agreeableness is related negatively to testosterone, & positively with serotonin (higher levels of testosterone linked with lower levels of agreeableness but higher serotonin)
criticisms of neural correlates of personality
- a lot of individual pieces of evidence
- no integrative view on personality as hardwired in the brain
Turkheimer (2000) 3 laws of behaviour genetics
- All human behavioral traits are heritable
- The effect of being raised in the same family is smaller than the effect of
genes - A substantial portion of the variation in human behavioural traits is not
accounted for by the effects of genes or families
heritability accounts for how much of the variance in personality traits?
between 20-50%
how much variance does shared environment account for
at best a small portion
much of the variance in heritability is attributed to what and why?
non-shared environment as much variance is unexplained by genes and shared environment
idea of nature via nurture
- Barlow (2020) argued that genes affect the way we perceive and react to the social world
- In Kendler (1997), twins were asked about their social support; genes accounted for 43–75% of variance in reported social support, while shared environment showed small effects.
- In fact, genes partly “cause”environment through self-selection: Individuals can choose to create and transform environments according to their preferences or needs, known as niche building
(genes determine how we create our environment. identical twins created a more similar environment than non-identical twins)
group socialisation theory (Harris, 1995) effect on personality
- With social categorisation, i.e., individuals have a tendency to place other individuals into social groups, being important
- An individual’s social identity is based on and derived from the groups one feels belong to and one’s perception of similarities and differences in relation to different social groups
- This theory attempts to explain what makes people similar as well as what makes people unique in personality
group processes influencing personality
context-specific socialisation
group socialisation
transmission of culture
between-group contrasts
within-group differentiation
context-specific socialisation
we learn from many sources and the learning is highly context-specific
group socialisation
we are socialised by the social groups we identify with
transmission of culture
culture is transmitted group-to-group, not merely parent to child
between-group contrasts
we behave in ways depart from the group we reject
within-group differentiation
while we imitate peer models, we also differentiate ourselves from our peers within-group
hofstede’s cultural dimension (1980)
- Hofstede (1980) collected survey data on attitudes of employees of IBM, involving close to 117,000 cases from 71 countries
- Four relatively independent dimensions were identified:
– individualism-collectivism
– power distance
– uncertainty avoidance
– masculinity-femininity
individualism-colelctivism dimension
degree to which a person is integrated into groups
(extent to which people feel independent)
power distance dimension
acceptance of economic and social inequality
(power distribution)
uncertainty avoidance dimension
the discomfort experienced in ambiguous or unstructured situations
masculinity-femininity dimension
assertiveness (masculinity) vs nurture (femininity)
what 2 further dimensions did Hofstede (2010) add?
long vs short term orientation
indulgence-restraint
long vs short term dimension
focusing on the future vs the present and past for one’s efforts
indulgence-restraint dimension
gratification vs control of basic human desires related to enjoying life
what does organisational culture refer to?
the long vs short term orientation and the indulgence - restraint dimensions
culture dimensions and personality
In a review, Triandis (2001) summarized that, comparatively, people in collectivist cultures are more likely to
– describe themselves as group members instead of as individuals
– emphasize collective goals
– pay more attention to external than internal determinants of social
behavior, and – be self-effacing
link between culture dimensions and self-construals
- The links between cultures and psychosocial outcomes can be explained by independent versus interdependent self-construals (Markus & Kitayama, 1991)
- In particular, people in individualist cultures tend to construct a self as independent of others and emphasise self-esteem
- In contrasts, people in collectivist cultures tend to construct a self that is inter-connected to their social groups and emphasis relationship harmony
- Relationship harmony can be seen as the functional equivalence of self-esteem in contributing to subjective well-being (Kwan et al., 1997)
relationship harmony diagram
individualist culture –> independent self-construal –> self esteem –> subjective wellbeing
collectivist culture –> interdependent self-construal –> relationship harmony –> subjective wellbeing
study finding:
Independent versus interdependent self-construal has been found to predict different ways of cognitive processing
For instance, Jiang & Sui (2022) found that experimentally priming the interdependent self-construal led to a reduced self-bias effect (i.e., faster and more accurate processing of self-relevant stimuli)
- In another study (Zhang et al., 2017), priming independent self- construal caused Chinese participants to self-evaluate more favourably when faced with threatening feedback (without the same priming threatening feedback resulted in less favourable self-evaluation among Chinese participants than non-threatening feedback)
