lecture 6-personality and genetics (including theories) Flashcards
What are some issues with heritability estimations
The additive assumption in estimating heritability vs the effects of environment is problematic
There are 3 types of genetic actions and their respective genetic variance are difficult to partition;
- Additive genetic actions (different genes act 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)
What is Eysenck’s biological model of personality
1976- suggested the human brain has two neural mechanisms: –
1.excitatory mechanism – keeps the individual alert, active and aroused –
2.inhibitory mechanism – causes inactivity and low energy
These two mechanisms are regulated by two independent circuits of arousal
He says extraversion Is linked to the arousal circuit responding to incoming stimuli (reticulo-cortical circuit)
He says introverts have over aroused circuits, extraverts have under aroused circuits
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 people are less aroused
Gray’s Reinforcement sensitivity theory (RST)
He says personality is based on the interaction between 3 basic systems in the brain: proposes three brain-behavioural systems that underlie individual differences in sensitivity to reward, punishment, and motivation
- Behavioural approach system= motivations to approach and causes the individual to be sensitive to potential rewards and to seek those rewards
- Behavioural inhibition system= comprises motivations to avoid based on conditioned sensitivity to potential punishment or non-rewarding processes. Within this, people will avoid situations as they know it will make them anxious
- Flight/flight/freeze system (FFFS) – a mechanism that responds to threat by a tendency to fight, take flight or freeze
The point to highlight from Gray’s theory is how the
notions of reward and punishment relate to impulsive and
anxious individuals. Impulsive people respond well to
rewards, and not well to punishment. Anxious individuals
respond well to punishment and not to rewards.
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 psycho biological model
Cloninger et al. (1993) proposed a psychobiological model of personality that includes four dimensions of temperament and three dimensions 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
Temperament= The four temperaments are thought to be organised as independent brain systems aligned to specific nerve cells or fibres that transmit nerve impulses by neurotransmitters. Cloninger links our personality to
those neurotransmitters that are responsible for the activation and inhibition of our behaviour and the learning and responses to both real and perceived rewards and punishmen
The four dimensions of temperament are: –
.novelty seeking = excitement, ‘behaviour activation’, like to meet new people, explore, impulsive. Connected to Dopamine,
.harm avoidance – caution, low risk behaviours, connected to serotonin.
.reward dependence – friendliness, seeking rewards, connected to noradrenaline
.persistence - stay with a task, not give up easily, persevere through frustration and tiredness. connected to noradrenaline
Character= the character traits in Cloninger’s theory contrast to temperaments because they are not biological in origin, but rather refer to how individuals understand themselves in their social world
Characters are based on 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
These aspects correspond to the 3 dimensions of character: – self-directedness - extent to which they are independent in mind and judgement
– Cooperativeness – self concept of how they fit into humanity and their social world
self-transcendence- self concept in beliefs about mystical experiences such as religion.
Cloninger’s model of personality is measured by the
Temperament and Character Inventory-Revised (TCI-R),
which contains 240 items
problems with psycho biological theories
- A main problem with psychobiological theories of personality is their 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 yet still accpeted in the model
- 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
- It has been argued that these theories may have oversimplified biological processes in their theory
adoption studies
- 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
