Identical twins (100% of genes shared)
approximately 46% variation in personality,
opposed to fraternal twins (share approx
50% of genes) showed approximately 23%
variation
Genetic make up of a person
contributes to the devlopment part of
the individuals personality
Genes account for
approximately 50% of
given traits
Genes increase the risk of
personality disorders
Anatomy of the central nervous system
Eysenck
Model of personality
Based on the results of
factor analyses of responses
on personality
three demensions of eprsonality:
extraversion, neuroticism, psychoticism
Extraversion
Extraverts are sociable and
active, they enjoy meeting people
and going to parties
Extraverts described as showing low levels of
cortical arousal, while introverts were seen as
over-aroused
Extraverts more sensitive to reward -
(introverts more sensitive to punishment)
Neuroticism
Reflecting differences
in the intensity of
emotional experiences
It might be expected that individuals high in
neuroticism might be more likely to use drugs in
order to reduce or avoid negative emotional
states
Psychoticism
Refers to a personality pattern
typified by aggressiveness and
interpersonal hostility
Individuals high on psychoticism are
tough-minded, non-conformist, willing
to take risks and may engage in
antisocial behaviour
Measure traits related to
anxiety and depression
Trait relates to
pschopathy/antisocial
personality disorder
Biochemistry
Hormones
Testosterone
a sense of separateness
aggression and risk-taking
sex drive (not touch affection)
and sexual fantasy
anxiety or energy leading to
poor concentration
assertiveness and
self-confidence
visual-spatial ability and
interest in moving objects
violent, criminal, or
psychotic behaviour
Estrogen
a stable mood and a
sense of well-being
feminine sexual behaviour
neuron growth and
improved cognition
Vasopressin
influences male social and sexual
behaviour, public communication, and
paternal pattern