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Personality - Biological theories (Y1) - Coggle Diagram
Personality - Biological theories (Y1)
Early biological theories - mostly discredited
Different levels of analysis - the same behaviour can be investigated on a behavioural, neurological, biochemical and molecular level
Humourism - Hippocrates and Galen - personality, temperament, influenced by humour balance
ideal personality and health states arise from a balance of all 4; blood (ST), yellow bile (CT), black bile (MT), phlegm (calm)
Sheldon's somatotypes - constitutional theory - ecto, meso and endo morphs
Physical build reflects personality
Phrenology - Franz Gall - the surface of the skull can be divided into 27 regions which reflect different traits and abilities
Personality is associated with different bumps and depressions on the skull
Phrenologists would feel the skull to measure personality
The theory has been discredited early on as pseudoscience, but represents advancement towards neuropsychology
Branches of psychology concerned with the physiological bases for personality
Neuropsychology - brain influences physiology
Psychophysiology - dealing with all aspects of biological functioning and the influence on psychological processes
Common aim - link behaviours to biological function
Assumes that all behaviour, such as personality and individual differences, can be influenced by physiological and neurological factors, with both approaches suggesting behaviour can be understood through exploring physiological factors
Genetics
Disentangling effects of genes and environment in psychological research -
Quantitative behaviour genetics; family, twin and adoption studies
Molecular genetics - pedigree studies, single gene association studies (candidate genes) and genome wide association studies (GWAS)
Twin studies - identical twins (MZ) share 100% of their genes and DZ share 50%
Both share identical environments
If similarity is stronger for identical twins and there is evidence of heritability
ACE model - variance = A + C + E; heritability or additive genetic components (A), non-shared environments (E) and shared environments (C) - makes them more different (E)
Heritability of personalit according to twin studies - examples of heritability estimates from mahjor twin studies - Eaves et al, 0.46-0.58, Loehlin et al, 2001 - 0.28-0.47
Adoption studies - comparing adoptive and biological families (siblings or parent-child)
Biological parents share 50% of their DNA with their biological child, whereas adoptive parents share 0% of their DNA
Correlations between adopted child and biological and adoptive parents
High correlation = biological cause
Molecular genetics - measuring actual genetic differences in the DNA and associating these differences with behaviour
In general, people do not carry genes that others do not - 99.9% of genes are identical
But people have different versions of the same genes - polymorphism (common variations in DNA sequence)
Some of these variants have been found to be associated with specific traits and behaviours
Genetic variants can be investigated individually or across the whole genome
Findings in terms of personality - individual gene variants - Sanchez-Roige, 2017:
Dopamine receptor D4 associated with novelty seeking
Serotonin transporter (5-HTTLPR) has been associated with neuroticism
Associations between personality traits and individual variants (candidate genes) often do not replicate and explain very little of personality
Genome wide association studies - may be more reliable but require larger samples
GWAS approach is hypothesis-free and data-driven
Several variants have been identified
Nagel (2018) - GWAS of neuroticism
Meta-analysis including N = 449,484 individuals
Identified 136 associated variants (after controlling the multiple testing)
But all variants explain only 4% of the variance
Summary - genetics of personality; according to all applied methods, personality traits have a significant genetic component
Twin studies suggest a heritability of 30-50% of the variance (remaining part explained by environmental factors
Although several genetic variants have been identified as being associated with personality, only a small number of variants are statistically significant
Usually explain little variance
Genetic component of personality is the result of many thousand gene variants with small effects
Eysenck's model
Ascending Reticular Activating System (ARAS) - balances excitatory and inhibitory neural mechanisms:
Reticulo-cortical circuit controls arousal from external stimuli - implicated in extraversion-introversion - generates more stimulation for introverts than extraverts, who then compensate by seeking more external stimuli e.g. social interaction and thrill seeking
Reticulo-limbic circuit controls arousal from emotional stimuli
Located in brain stem, conencted to thalamus, hypothalamus and cortex
Manages amount of information or stimulation brain receives to mediate sleep, maintenance of alertness and activity - arousal
Arousal is the central variable to extroversion-introversion
Extraversion and cortical - introverts have a lower tolerance for external stimulation (hypothesis)
Without stimulation, their cortical arousal is in a comfortable position - stimulation leads to feeling uncomfortable as they are overstimulated
For extroverts, their baseline arousal is below comfortable leading to boredom, and so seeking external stimuli arouses the cortical circuit to a comfortable level
The Lemon Juice Test, Corcoran (1964) and Eysenck & Eysenck (1967) -
Reticulo-cortical circuit also regulates food response (salivation) - salivation indicates a level of arousal from RCC
Introverts have increased activity in the ARAS, and so should salivate more in response to food stimuli, in this case lemon juice drops
100 participants, half male half female, measured on Eysenck extraversion measure
4 drops of lemon juice on tongue for 20 seconds
Introversion correlated strongly with saliva production
Furnham et al, 1994 - do introverts find background noise more distracting?
60 participants, Eysenck extraversion measure
20 highest extraversion and 20 higher introversion selected
Two difficult reading comprehension tests - one in silence, one with TV on
Better score in silence than with TV on for introverts, same score for extraversion across both
Supports idea of ARAS - introverts are more impaired by having the TV on, and so it is too stimulating (distracting) for introverts
Dobbs et al, 2011 - is the TV distracting simply because it features people talking
Conceptual replication of Furnham et al, 1994
Silence v music (UK garage) v assorted people noises
118 female participants
Perceptual reasoning test
Introverts achieved a better score in silence than any sounds
Introverts impaired by sounds, extraverts unaffected, introverts more impaired by noise than music - effects not solely attributable to sensitivity to people talking
Zakary and Lobel, 1983 - are introverts better able to cope with sensory deprivation -
33 male participants, Eysneck extroversion measure, perceptual deprivation for 3 hours, self-report of overall feeling (bad-great)
Extroverts felt worse after suggesting they need more external stimulation
Hagemann et al (2009) - EEG activity shows extroverts are cortically less aroused than introverts
Eysenck's model - Reticulo-Limbic Circuit controls arousal from emotional stimuli
Implicated in neuroticism
Neurotics are more inactive to emotional stimulation and are more susceptible to emotional arousal
Psychological reactivity - Larsen and Ketalaar (1991) - 359 undergraduates
Eysenck neuroticism measure
Mood induction - write about what it would be like too... positive, neutral and negative experience - self report about positive and negative affect
Do neurotics feel the negative affect more greatly?
No effect on positive affects
Negative affect more profound among neurotics - more impacted by negative outcomes
Physiological reactivity - Norris et al, 2007: 61 female students, 66 pictures, ranging in pleasant to unpleasant
emotional stability measure
Skin conductance test
Do pleasant / unpleasant stimuli elicit greater skin conductance amongst neurotics?
Skin conductance reactivity higher for pleasant and unpleasant stimuli v neutral
Greater skin conductance in neurotics
RCC - manages arousal generated by incoming stimuli - high arousal for introverts, low arousal for extraverts
RLC - high arousal to emotional stimuli, leading to neuroticism, low arousal to emotional stimuli leads to emotional stability
Gray's Reinforcement Sensitivity - two temparaments of anxiety and impulsiveness
Behavioural approach system - seeks rewards;
tendency to seek rewards and view events as having potential for rewards -> impulsive behaviour
We approach potential rewards and the BAS regulates behaviour in presence of reward signals
Impulsive people are more sensitive to reward signals
Behavioural inhibition system - avoids punishment
tendency to avoid punishment and to view events as having potential for punishment -> highly anxious
We avoid potential punishment
BIS regulates behaviour in the presence of punishment signals (e.g. anxiety)
Anxious people are more sensitive to punishment signals
Differences in personality can be attributed to relative strengths of BIS and BAS systems
Fight-flight-freeze system - threat system: represents more natural response to averse stimuli which the individuals shows a fight response to averse stimuli, or a fear response
Measuring BIS/BAS - Carver and White, 1994 - BIS is unidimensional, BAS is multidimensional
BIS - worry
BAS - drive, fun seeking, reward-responsiveness
BIS scores as a predictor of anxiety - 69 undergraduates, BIS measures and a mood / anxiety measure in a pattern recognition task
Cold pressor test - can improve performance - told task performance was poor
Mood anxiety measure following this
Higher BIS scores associated with greater follow-up anxiety scores
BAS scores as a predictor of reward - 90 undergraduates - course credit:
BAS measure and a happiness measure
Told they could earn an extra credit by performing well on the task, told they were doing great
Happiness measure again
Higher BAS scores associated with greater follow up happiness scores
BAS scores as a predictor of addiction - Franken et al, 2006 -
Higher BAS drive, fun seeking and total among drug addicts than healthy controls
Physiological reactivity - Balconi et al, 2012 - 25 female students, BIS/BAS wore EEG monitor
Rated 50 positive, 50 negative, 25 neutral images
Those with higher BAS - positive pictures rated more positive, heightened skin conductance
Those with higher BIS - negative pictures rated more negative, heightened skin conductance for negative images
Anxious people - high BIS - respond more to anxiety provoking stimuli
Impulsive people - high BAS - respond more to rewards
Cloninger's Biological Model of Personality
7 dimensions - four temperament domains and three character domains
4 temperament domains -
novelty seeking - behaviour activation, related to dopaminergic system in frontal lobe (extroversion, conscientiousness and BAS)
harm avoidance - behaviour inhibition, related to serotonergic system, neuroticism, introversion
reward dependence - behaviour maintenance, related to norepinephrine (noradrenaline) - extroversion, openness, BAS
persistence - behaviour maintenance, related to norepinephrine, conscientiousness
3 character domains -
self-directedness - conscientiousness
cooperativeness - agreeableness
Self-transcendence - openness
The model maps on Eysenck, Gray and the Big Five (De Fruyt et al, 1999)
Cloninger's model - how personality leads to each of the 7 dimensions:
Personality, narrative self leads to temperament and character domains through unconscious automatic reactions and conscious self aware plans respectively
Character and temperament maintain one another through meaning and salience
Temperament creates procedural learning (associative conditioning) and thus a habit system of:
-> passive avoidance (creates harm avoidance)
-> incentive activation (creates novelty seeking),
-> social attachment (creates reward dependence)
-> partial reinforcement (creates persistence)
Character leads to propositional learning and a conceptual system - producing:
-> Individual (leading to self-directedness)
-> Society (leading to cooperativeness)
-> Universe (self-transcendence)
Evaluating biological theories
Explanation -
links (observable) physiology to personality
genetic foundation of personality included
often too reductionist or deterministic, and does not account for environment or cognition
Empirical validity -
weak and inconsistent evidence
Little evidence that neuroticism is linked to arousal
ARAS may not be important for arousal
Biological processes in models are oversimplified
Arousal, activation and inhibition are important variables that allow personality to be linked to many different types of behaviours and responses to stimuli
Eysenck - first attempt to examine personality biologically
Lack of consistent evidence - Matthew and Gililand's study showed that physiological and psychological links are weak at best, with neuroticism barely being linked to arousal, even with extroversion being linked to activation
This could be due to the reductive nature of Gray, Cloninger and Eysenck's theories - ARAS according to Zuckerman (1991) is more complex in it's arousal regulation than Eysenck suggests
A combination of all three theories may be best - Cloninger's ideas of neurotransmitters, paired with Eysenck's suggestion about activation and arousal, and Gray's BIS/BAS would create a more full image of personality being caused by biological factors
-> How we are is due to the interaction of these systems of arousal and activation which produce our personality characteristics e.g. low arousal in ARAS leads to extroversion to bring stimulation to a baseline
Empirical evidence for biological theories of personality -
Eysenck - extroversion related to measures of stimulation, and neuroticism measures of emotion
Gray - high sensitivity to signals or punishment or impulsivity and high sensitivity to rewards associated with anxiety
Matthew and Gilliland (1999) - central nervous system and biological personality dimensions
CNS - supervises and coordinates activity of entire nervous system, transmits sensory information - measured with brain activity, alpha reflects arousal
Gale (1973) - high levels of alpha activity in introverts in aroused situations (low arousal) than extroverts
Stenberg (1992) - no relationship between EEG measures and Eysenck's dimensions
ERP - higher amplitudes of p300 associated with extroversion (area involved in social based stimuli of facial response)
EEG for Gray - impulsive participants have lower arousal, and anxious participants have higher beta waveforms in response to negative emotional stimuli
Weakly supported relationship
Autonomic nervous system - involuntary actions - studied with electro modal measures (EDA) which measure electrical activity in the skin
Baseline EDA and phasic EDA (skin responses)
Eysenck - increased heart rate to arousal stimuli for introverts, but there is little support that EDA can discriminate between introverts and extroverts
Neuroticism not related to EDA
Other biological and physiological systems -
dopamine - extroversion is related to higher mesolimbic dopamine system sensitivity (Depue and Collins, 1999)
Cohen et al (2005) - also found that extroversion is related to dopamine activation during a gambling task
Johnson et al (1999) - extroversion is related to blood flow activity in the anterior cingulate cortex, temporal lobe and the posterior thalamus - this finding suggests extroversion is related to reward-sensitive regions of the brain
Gray - anxiety is associated with high sensitivity signals of punishment and impulsivity and reward - backed up by a study from Arnett and Newman (2000) which found increases in heart rate when people are rewarded
Consistent with predictions around the BIS regarding punishment and its relationship to physiological respsones
