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BIOLOGICAL THEORIES OF PERSONALITY - Coggle Diagram
BIOLOGICAL THEORIES OF PERSONALITY
what are people like ?
why do they behave as they do?
how do they become that way?
PERSONALITY AND BIOLOGY
the idea that individual differences in personality might have a biological basis is nothing new
the 4 humours
personality is related to the level of four different bodily fluids
individuals who have different levels of body fluid will therefore show different personalities
facial features
size and shape of the body
PERSONALITY AND THE BRAIN
PHINEAS GAGE
25 year old
tamping iron - set off an explosion
the explosion occurred too early blowing the tamping iron through his skull, destroying a significant part of his frontal lobe
survived, could talk and walk
before accident - serious, energetic, responsible
the accident sparked interest in the possible relationship between brain functioning and personality
after accident - irresponsible, reckless, dis-inhibited
MODEL 1 - AROUSAL THEORY OF PERSONALITY
Eysenck was among the first psychologist to suggest there was a link between human biology and personalitya
assumed that the brain has 2 distinct sets of neural mechanisms
this balance is regulated by the ascending reticular activating system - ARAS
excitatory mechanism - keeps us alert, active, aroused
assumption 2 - individuals seek to maintain a balance between the excitatory and inhibitory mechanisms
ARAS
found in the brain stem
closely connected to other areas of the brain - thalamus, hypothalamus, cortex
specifically, two neural circuits were believed to regulate the level of cortical arousal we experience
Reticulo-cortical circuit - responsible for controlling cortical
the ARAS can be thought of as a gate or a dam, regulating the level of arousal in the brain
EXTROVERSION AND INTROVERSION
Eysenck suggested that the ARAS operates differently in extroverts and introverts
introverts - ARAS allows too much arousal in
the ARAS consistently lets in arousal from external stimulation
therefore more easily to be aroused and likely to experience chronically higher levels of cortical arousal
introverts will often avoid situations where further stimulation is likely
assumption - personally traits are normally distributed
extroverts - ARAS allows too little arousal in
Extroversion - the ARAS continually cuts the brain off from external stimulation
less likely to be aroused and likely to experience chronically lower levels of cortical arousal
extroverts will seek out situations where further stimulation and excitement are likely
BEHAVIOURAL EVIDENCE
lemon juice test - introverts produce more significantly more salivia in response to lemon juice drops than extroverts
because of their higher cortical arousal introverts were expected to experience a greater salivary response than extroverts under conditions of equal response
pain - introverts are less tolerant of painful electric shocks than extroverts - Petrie, 1967
music - extroverts and introverts prefer the music of different intensities whilst working on a learning task and perform best at their chosen level of intensity - Geen, 1984
NEUROPSYCHOLOGICAL EVIDENCE
Johnson et al 1999
PET study - the frontal lobes of introverts were found to be more active than extroverts
NEUROTICISM AND AROUSAL
eysenck also suggested neuroticism was related to arousal of the 'reticulo-limbic system'
the limbic system of neurotic individuals is more easily aroused in emotional stimulation
neurotic individuals are also thought to experience high levels of autonomic nervous activity - ANS
ANS activity is slower to decrease once the threat has gone
CANLI ET AL 2001
participants were shown 20 negative and 20 positive pictures whilst in the fMRI scanner
individuals with high neuroticism scores showed greater brain reactivity to negative stimuli
extroversion - low cortical arousal
neuroticism - high cortical arousal
emotional stability - low limbic arousal
neuroticism - high limbic arousal
MODEL 2 - sensitivity to reward and punishment - Gray, 1970, 1981, 1987
Gray put forward an alternative biological model of personality known as 'reinforcement sensitivity theory'
personality stems from interaction between 2 basic systems in the brain
BEHAVIOURAL APPROACH SYSTEM - BAS
responsible for our sensitivity to potential rewards and motivated us to seek those rewards
BAS activity linked to an individuals level of impulsivitiy
high BAS - impulsive
low BAS - low impulsivitiy
under sensitive BAS - depression
BEHAVIOURAL INHIBITION SYSTEM - BIS
responsible for our sensitivity to punishment or potential danger and motivates us to avoid these rewards
BIS activity linked to an individuals level of anxiety
high BIS - anxiety
low BIS - low anxiety
oversensitive BIS - depression
this model suggests that impulsivity and anxiety might better explain human personality
high impulsivity - HIGH BAS
low impulsivitiy - LOW BAS
high anxiety - HIGH BIS
low anxiety - LOW BIS
BEHAVIOURAL EVIDENCE
CARVER AND WHITE 1994
developed a self report measure to assess individual differences in BAS and BIS sensitivity
cold pressor pain - participants told that cold presser procedures - 60 secs in ice water - would improve their performance on an intuitive task
NEUROPSYCHOLOGICAL EVIDENCE
brain activity
research suggests that the approach (BAS) and avoidance (BIS) systems are independent
MODEL 3 - SENSITIVITY TO REWARD, PUNISHMENT AND AROUSAL - ZUCKERMAN 1995
Zuckerman proposed a slightly different model that claimed to explain the neurological basis of the big 3 personality traits
suggested that extroversion, neuroticism and psychoticism were determined by different neural systems concerned with reinforcement, punishment and arousal
extroversion - highly sensitivity to reinforcement
neuroticism - high sensitivity to punishment
psychoticism - low sensitivity to punishment, an abnormally high optimal level of arousal
MODEL 4 - TEMPERANT DOMAINS AND CHARACTER TRAITS - CLONINGER 1987, 1993
developed a general model of personality based on the findings of a variety of different kind of studies, neurological, psychometric testing, genetics
suggests that personality was based on the activity of 4 temperant domains based on biological systems
NOVELTY SEEKING
associated with impulsive behaviour
score highly on this = like excitement and respond positively to new stimuli
linked to dopamine levels
HARM AVOIDANCE
associated with cautious and low risk behaviour
score highly = respond intesively to aversive stimuli and tend to inhibit their behaviour to avoid punishment and novelty
harm avoidance thought to be linked to serotonin levels
REWARD DEPENDENT
associated with reward seeking behaviour
score highly - respond well to rewards, praise, approval from others
reward dependence thought to be associated with noradrenaline
PERSISTENCE
associated with the tendency to persevere with behaviour despite frustration and fatigue s
score highly = maintain their behaviour and continue with a task regardless of how frustrating or difficult
linked to noradrenaline levels
also suggested that there were 3 character traits
not biological in origin - thought to represent emotions, goals and intellectual abilities we have learnt in response to the outside world
self-directedness - autonomy
cooperativeness - relationship with others
self transcendence - beliefs concerning spirituality
the interaction between temperament and character traits was believed to determine an individuals personality
there is clearly a lot of overlap between these biological theories of personality
PERSONALITY AND NEUROSCIENCE
recent evidence has also found an association between the big 5 personalities and the volume of different brain regions