Week 6: Personality (genetic, neurobiological, and socio-cultural perspectives)

Big Five Personality Model

The most robust model of personality, whose structure has been confirmed extensively using factor analysis.

What did Riemann et al. (1997) discover about personality traits in twin studies

• Monozygotic twins had a mean correlation of 0.50 of ‘the big 5’ traits

• Dizygotic twins had a mean correlation of 0.22

Outline Falconers’ formula

Heritability can be calculated as:

(MZ correlation - DZ correlation) x 2 = 2 heritability rate

What did Loehlin et al. (1985) study about personality?

They found larger correlations between children and biological parents (16-34) compared to children and adoptive parents (02-12) on a number of traits

What did Hershberger et al. (1995) study about personality?

They found that identical twins reared apart did not show lower correlations on extraversion and neuroticism than identical twins reared together - but did on openness.

What did Bergeman et al. (1993) study about personality?

They found that genetic influence was ‘substantial’ for openness (40%) and conscientiousness (29%), but weak for agreeableness (12%) and that ‘there was little evidence of shared rearing environment’

What are the 3 types of genetic actions?

1. Additive genetic actions

2. Dominant genetic actions

3. Epistatic genetic actions

What is meant by ‘additive genetic actions’?

Different genes work independently

What is meant by ‘dominant genetic actions’?

Dominant genes suppress expression of recessive genes

What is meant by ‘epistatic genetic actions’?

Certain genes determine whether other genes will be expressed or suppressed

What two neural mechanisms did Eysenck (1967) suggest that the human brain has?

• Excitatory mechanism: keeps the individual alert, active and aroused

• Inhibitory mechanism: causes inactivity and low energy

What did Eysenck propose extraversion is linked to?

Extraversion is linked to the arousal circuit responding to incoming stimuli (reticulo-cortical circuit)

→ Introverts have over-aroused circuits, extraverts have under-aroused circuits

What did Eysenck propose neuroticism is linked to?

Neuroticism is linked to the arousal circuit responding to emotional stimuli (reticulo-limbic circuit)

→ In stressful situations, neurotics would be more emotionally aroused while emotionally stable individuals are less aroused

What did Geen (1984) propose about the differences between introverts and extraverts?

Geen (1984) asked introverts and extraverts to choose noise levels of music to listen to while doing a difficult and boring task

• 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

What did Kehoe et al. (2012) discover about the link between neuroticism and arousal?

They 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

Outline Gray’s reinforcement sensitivity theory (RST)

Gray (1970) proposes personality based on the interaction between three basic systems in the brain:

• Behavioural approach system (BAS) - comprises motivations to approach and causes the individual to be sensitive to potential rewards and to seek those rewards

• Behavioural inhibition system (BIS) - comprises motivations to avoid based on conditioned sensitivity to potential punishment or non-rewarding stimuli

• Fight/flight/freeze system (FFFS) - a mechanism that responds to threat by a tendency to fight, flight or freeze

What did Gray suggest as an adaptation of Eysenck’s model?

• Gray (1990) proposed that sensitivity to reward and punishment are two independent dimensions

• Eysenck’s E and N dimensions should be adapted to more casually important dimensions of ‘punishment sensitivity’ (anxiety) and ‘reward sensitivity’ (impulsivity)

→ Explains why introverts are more aroused: they are punishment sensitive/anxious

→ Extraverts are reward sensitive (impulsive)

Outline Cloniger’s psychobiological model - what are the 4 dimensions of temperament?

The four dimensions of temperament are:

• Novelty seeking (dopamine)

• Harm avoidance (serotonin)

• Reward dependence (norepinephrine)

• Persistence (norepinephrine)

→ organised into independent brain systems, although there is neurotransmitter overlap

What are the 3 dimensions of character according to Cloniger?

• Self-directedness

• Cooperativeness

• Self-transcendence

What are the limitations of psychobiological theories?

• Limited empirical support for some aspects.

• The relationship between neuroticism and arousal is less supported than extraversion and arousal.

• Stewart et al. (2004) found Cloninger's traits resembled the Big Five and Eysenck's model more than the original seven-factor model.

• Biological processes may be oversimplified.

What are the neural correlates of extraversion?

• Linked to dopamine and the brain's reward network.

• Associated with positive responses to pleasant stimuli.

• Linked to the medial/orbitofrontal cortex (mOFC), involved in monitoring reward value.

What are the neural correlates of neuroticism?

• Linked to the amygdala, which responds to danger and emotional stimuli.

• Also linked to the medial and dorsolateral prefrontal cortex, which help regulate negative emotions.

• Serotonin may influence neuroticism, but the relationship is complex.

What are the neural correlates of agreeableness?

• Linked to empathy, including:

  • Mentalising: understanding other people's perspectives.

  • Mirroring: experiencing or recognising others' emotions.

• Mentalising involves the default network.

• Emotional mirroring involves the insula and midcingulate cortex.

• Positively associated with serotonin and negatively associated with testosterone.

What are the neural correlates of openness?

• Linked to individual differences in dopamine function.

• Associated with processing stimulus salience (how noticeable or important something is).

• Linked to the dorsolateral prefrontal cortex and default network.

• The default network is particularly active during passive tasks, self-generated thought, remembering and future planning.

What are the neural correlates of conscientiousness?

• Linked to the dorsolateral prefrontal cortex (dlPFC).

• Associated with the goal-priority network, which helps prioritise goals and avoid distractions.

• Also linked to functional connectivity within this network.

• Possible association with serotonin, although evidence is inconclusive.

What are the limitations of research into neural correlates of personality?

• Increasing evidence links personality traits to brain activity.

• However, there are many individual research findings.

• There is no complete, integrated explanation of personality as being hardwired into the brain.

What are Turkheimer’s (2000) three laws of behaviour genetics?

1. All human behavioural traits are heritable.

2. Being raised in the same family has a smaller effect than genes.

3. A substantial amount of variation in behaviour is unexplained by genes or shared family environment.

What is the nature via nurture approach in regards to personality?

• Genes influence personality, but the environment also plays an important role.

• Heritability accounts for approximately 20–50% of personality variation.

• Shared environment explains relatively little variation.

• Non-shared environment explains much of the remaining variation.

What is the difference between shared and non-shared environments?

• Shared environment: experiences siblings have in common, e.g. family home.

• Non-shared environment: individual experiences that differ between siblings, e.g. different friends, peers and aspects of parenting.

What is niche-picking and niche-building?

• Genes influence how individuals perceive and respond to their environment.

• Niche-picking: choosing environments that suit existing personality traits.

• Niche-building: actively creating or changing environments to suit personal preferences

How do genes influence environmental choices?

Example:

• Someone born with a highly reactive amygdala may have higher baseline arousal.

• They may prefer quieter environments and avoid stimulating situations.

• Their genetic characteristics influence the environments they choose.

What is Harris’ (1995) group socialisation theory?

• Personality is influenced by non-shared environmental experiences.

• Individuals are socialised by the social groups they identify with.

• Social identity develops through group membership and perceived similarities and differences.

What are the group processes that influence personality?

• Context-specific socialisation: learning differs depending on the situation.

• Group socialisation: individuals are influenced by groups they identify with.

• Transmission of culture: culture is passed between groups, not just from parents to children.

• Between-group contrasts: individuals behave differently from groups they reject.

• Within-group differentiation: individuals imitate peers but also try to distinguish themselves from them.

What did Hofstede (1980) investigate?

• Collected survey data from approximately 117,000 IBM employees across 71 countries.

• Identified four main cultural dimensions.

• Later, two additional dimensions were added.

What are Hofstede's original four cultural dimensions?

1. Individualism vs collectivism: importance of individual independence versus group belonging.

2. Power distance: acceptance of economic and social inequality.

3. Uncertainty avoidance: discomfort with ambiguous or unstructured situations.

4. Masculinity vs femininity: assertiveness versus nurturing values.

What two additional dimensions did Hofstede et al. (2010) introduce?

• Long-term vs short-term orientation: focus on future goals versus the present and past.

• Indulgence vs restraint: freedom to enjoy basic desires versus controlling them.

What are the limitations of Hofstede’s cultural dimensions?

• They describe cultures, not individuals.

• Original research focused on workplace attitudes.

• Therefore, they are often referred to as organisational culture dimensions.

How do collectivist cultures differ from individualistic cultures?

Collectivist cultures:

• Emphasise group membership and collective goals.

• Focus more on external influences on behaviour.

• More likely to be self-effacing.

Individualist cultures:

• Emphasise independence and individual identity.

• Focus more on personal goals and self-esteem.

What are independent and interdependent self-construals?

• Independent self-construal: seeing yourself as separate from others; common in individualist cultures.

• Interdependent self-construal: seeing yourself as connected to social groups; common in collectivist cultures.

• Relationship harmony contributes to well-being in collectivist cultures.

What did research by Jiang and Sui (2022) and Zhang et al. (2017) find?

• Jiang and Sui: priming an interdependent self-construal reduced the self-bias effect.

• Zhang et al.: priming an independent self-construal caused Chinese participants to evaluate themselves more positively.

• Suggests culture influences cognitive processing and self-perception.

What is the HEXACO Model?

A 6-factor model of personality proposed by global research that may better explain personality.

→ Honesty - Humility

→ Emotionality

→ Extraversion

→ Agreeableness

→ Conscientiousness

→ Openness to experience