Download Personality

Biological Basis of Personality:
Genetics and twins studies
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123 pairs of
identical twins and
127 pairs of
fraternal twins
Measured on “Big
Five” personality
dimensions
Results suggest
that personality
differences in the
population are 40 60% heritable.
Biological Basis:
Genetics and adoption studies
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The personality of adopted siblings
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No more alike than randomly selected persons
Largely unrelated to adoptive parents
Doesn’t parenting style affect adult personality?
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Peers, not adults, exert the most influence on
personality (Rowe, 1994; Harris, 1998)
But a minimum amount of parenting is critical for the
avoidance of antisocial behavior (Lykken, 2000)
Biological Basis:
Specific genes for specific traits?
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A gene that regulates a particular dopamine receptor
is associated with novelty seeking
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One form of this gene produces deficiency in dopamine and
people seek out novel experiences to increase the release of
dopamine, which is related to feelings of reward and
pleasure
A gene that regulates serotonin is associated with
neuroticism and agreeableness
However, typically, a personality trait will be a product
of many genes and the presence of an environment
appropriate for gene expression
Biological Basis:
Temperaments in Infancy
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Temperament
 A general tendency to feel or act in a certain way that is strongly linked to
biology
 If infants show such tendencies, these tendencies must be “hard-wired”
(i.e., must be biological) since the environment has not yet had a chance
to exert its influence
Shyness (Kagan & Snidman, 1991)
 15-20% of newborns (as young as 6 weeks) respond to new situations or
strange objects by becoming distressed (i.e., crying, etc.)
 At 4 years old, these children are described as shy by their parents
 Likely to be shy as a teenager
 More likely to be depressed as a young adult
The Neurophysiological
Mechanisms of Extraversion
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Extraversion
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Less than optimal levels of activity in the ascending reticular
activating system (part of the brain stem)
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Chronic underarousal leads extraverts to seek stimulation
Extraverts work and perform better in noisy environments
The behavioral approach system (BAS) is stronger in
extraverts
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The BAS leads organisms to approach stimuli in search of rewards
Extraverts have heightened dopamine activity in the reward center of
the brain (i.e., the nucleus accumbens, a part of the limbic system)
Extraverts report high levels of energy, desire, and self-confidence
The Neurophysiological
Mechanisms of Introversion
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Introversion
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Greater than optimal levels of activity in the ascending
reticular activating system (part of the brain stem)
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Chronic overarousal leads introverts to avoid stimulation
Introverts are more sensitive to stimulation, including pain
The behavioral inhibition system (BIS) is stronger in
introverts
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The BIS is sensitive to punishment and leads organisms to inhibit
behavior that might lead to danger or pain
Introverts have heightened activity in the frontal lobes (which are
known to inhibit socially inappropriate behavior) and in the amygdala
(which processes stimuli related to punishment and fear)
Introverts are anxious about social situations because they fear
negative outcomes
Personality Is
Evolutionarily Adaptive
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Natural selection has shaped the human genome over the course of
evolution.
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Adaptive personality traits were passed along to increasing numbers of
individuals in future generations.
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But if traits are adaptive, why are there such great individual
differences among people?
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For example, It is easy to imagine how being competitive might lead a person to obtain
great rewards and how being competitive would be passed on.
Natural selection ought to make people more similar rather than more different.
Individual differences may be the result of evolution having endowed
us with multiple strategies for survival
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The strategy an organism selects depends on the particular environment
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For example, a competitive person in a cooperative society (or a cooperative person in
a competitive society) would have a distinct advantage
Such diversity within a group may confer a selective advantage over groups that
have less diversity
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For example, it may be good for a group to have both competitive and cooperative
members
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Competitive individuals often risk their physical well-being and hence do not survive, while
cooperative members do
Personality Consistency over Time
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In general, personality is
consistent over the
lifespan
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Where you rank relative
to others on personality
traits changes relatively
little over time.
This supports the
notion that traits are
hard-wired
However, is personality
more consistent at some
points in the lifespan?
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Evidence indicates that
personality is least
stable during childhood
Consistency increases
with age
Personality Change over Time
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Your rank order relative
to others on the trait of
conscientious changes
relatively little over time
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If you’re very
conscientious relative
to others when you’re
20 years old, the same
will likely be true when
you’re 50 years old
However,
conscientiousness in
everyone tends to
increase over time
This is true in multiple
cultures
Levels of personality (McAdam):
Some change, some don’t
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Dispositional traits (or basic tendencies)
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Personal concerns
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The Big Five
Not likely to change in a particular individual over time
These, and the strategies we use to meet them, change according to
situation or developmental stage
However, even though the particular concerns and strategies change,
the way they change corresponds to a person’s basic tendencies
Thus, these changes are often called characteristic adaptations
Life stories
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These evolve over time to provide a person’s life with a sense of unity
and meaning
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For example, someone might see themselves as having a “rags to riches” life
story
Personality change: Brain injury and
psychological medications
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Phineas Gage
Alzheimer’s disease
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There is some evidence that personality changes are the
first signs of early stage Alzheimer’s (Moran et al., 2004)
Prozac
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Antidepressant that works by increasing the activity of
serotonin
When taken by individuals without depression, it can cause
personality changes, such as
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Increased social dominance and extraversion
Decreased hostility and neuroticism
The self: Self-awareness
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Self-concept
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Self as “I” (knower) vs. self as “me” (known)
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Who you think you are.
Influences your daily choices.
The knower is you thinking, feeling, making decisions, etc.
The known (the objectified self) is the knowledge you hold about your self; your
self-concept
Self-awareness theory
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The “I” thinking about the “me”
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We spend only about 8% of our time thinking about ourselves.
Objective self-awareness pushes us to act in accordance with our self-concept
Self-discrepancy is the awareness that we are not acting in accord with our selfconcept
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This realization can generate negative emotions within ourselves
See next slide
Self-Awareness Theory
Self-Conscious
Persons
Change Behavior to
Match Standards
SelfAwareness
Self-focusing
situations
SelfDiscrepancies
Escape from SelfAwareness
Escape from self-awareness is sometimes
accomplished through the consumption of alcohol. This
can also provide an excuse for future failures.
The self: Self-schema
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Self-schema
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The cognitive component of our self-concept
The working self-concept
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The immediate (present moment) conception of our self
This can change from situation to situation
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That is, the working self concept is formed “on-line”
Independent vs. interdependent self-construals
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People that live in individualistic cultures tend to have independent selfconstruals
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People that live in collectivist cultures tend to have interdependent selfconstruals
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In an individualistic (typically Western or industrialized) culture, personal goals
and preferences take priority over group allegiances.
In a collectivist (typically Eastern or agrarian) culture, cooperation and group
harmony take priority over purely personal goals.
See the next two slides
The self: Self-esteem
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Self-esteem
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The evaluative or emotional component of the self-concept
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Reflected appraisal
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Exaggerations of personal importance reflect attempts to buffer anxiety about
inevitable death.
Self-esteem is only weakly related to objective life outcomes.
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When a person behaves in ways that lead to rejection by their social group, their
self-esteem will be reduced.
Terror management theory
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In large part, people view themselves as others view them.
Sociometer theory
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Am I worthwhile or worthless? Good or bad?
Although people with high self-esteem do report more happiness.
There are some downsides to having high self-esteem.
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When some people with high self-esteem are challenged, they can become
bullying, violent, or boastful.
The Self-Esteem Cycle
High Self-Esteem
Self-Credit
Positive Expectations
Success
High Effort
Low self-esteem and negative self-evaluations are
related to pessimistic explanatory styles, which in turn are
related to negative consequences for the immune system.
The self: Positive illusions
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People think of themselves in overly favorable terms
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The better-than-average effect.
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Self evaluative maintenance
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Self-esteem is influenced by
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An individual’s performance
How relevant that performance is to that individual’s self-concept
How that performance compares to the performance of people that are
significant to that individual
Social comparison
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Most people describe themselves as above average in almost every way.
People with low self-esteem tend to make upward comparisons with
others that are superior to them.
Self-serving bias
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People with high self-esteem take credit for success, blame failures on
outside factors, and attribute criticism to envy or prejudice.