personality chapter 7
brain activity
Brain spontaneously produces small amounts of electrical activity Can be measured by electrodes on scalp—electroencephalograph (EEG) Evoked potential technique—uses EEG, but the participant is given a stimulus and the researcher assess specific brain response to stimulus brain imaging technique
brain imaging technique
map structure and function of brain Positron emission tomography (PET) Functional magnetic resonance imaging (fMRI)
Hebb's theory of optimal level of arousal
that people are motivated to reach an optimal level of arousal -if they are under aroused, relative to this level, an increase in arousal is rewarding. -if they are overaroused, a decrease in arousal is rewarding people are motivated to seek out tension and stimulation
Functional magnetic resonance imaging (fMRI)
A noninvasive imaging technique that uses magnetic fields to map brain activity by measuring changes in the brain's blood flow and oxygen levels
serotonin
Associated with depression and other mood disorders Low levels are people that are high in neuroticism
Norepinepherine
Associated with fight or flight response
dopamine
Associated with pleasure (cocaine) Very responsive to reward
Morningness-Eveningness
Being a "morning-type" or "evening-type" of person is a stable characteristic Due to differences in underlying biological rhythms Many biological processes fluctuate around a 24-25 hour cycle—circadian rhythm; e.g., body temperature, endocrine secretion rates But wide individual differences are in the circadian rhythm, identified through temporal isolation studies -Live in quarters for a week where you can't tell if its night or day Related to physiology, dictated by your circadian rhythm cycle Individuals with shorter circadian rhythms hit peak body temperature and alertness earlier in day, get sleepy earlier, than individuals with longer rhythm (morning people: people who have less than a 24 hour cycle) Morningness-Eveningness Questionnaire Cross-cultural replication and documentation of stability of characteristic
cardiovascular activity
Blood pressure -Measure of, e.g., stress reactivity Heart rate -Increases with anxiety, fear, arousal, cognitive effort cardiac reactivity
neurotransmitters
Chemicals in nerve cells are responsible for the transmission of nerve impulse from one cell to another
Neurotransmitters and Personality
Cloninger's Tridimensional Personality Model: Novelty seeking (new things/adventures) -Low levels of dopamine -Doesn't have to be risk taking Harm avoidance: -Low levels of serotonin Reward dependence -Low levels of norephinepherine -Constantly seeking reward in the environment -Behavior dictated toward reward Not a good theory for accounting for all personality Good for novelty seeking
Physiological Measures Commonly Used in Personality Research
Electrodermal Activity (Skin Conductance) Cardiovascular activity Brain Activity Other measures: Biochemical analyses of blood and saliva
Monoamine Oxidase (MAO)
Enzyme that maintains a proper level of neurotransmitters (Dopamine + Serotonin) If you inhibit MAO with MAOI, you enable the more neurotransmitters in the system
Physiologically Based Theories of Personality
Extraversion-Introversion Sensitivity to Reward and Punishment Sensation Seeking Neurotransmitters and Personality Morningness-Eveningness Brain Asymmetry and Affective Style
cardiac reactivity
Greater than normal increase in blood pressure and heart rate when performing task such as backward serial subtraction Associated with Type A personality—impatience, competitiveness, hostility Cardiac reactivity (and Type A) associated with coronary heart disease
Integration with Eysenck's model of reward and punishment system
Impulsive = high extraversion, moderate neuroticism Anxious = moderate introversion, high neuroticism
evening
Individuals with longer rhythms tend to be ____ persons Peak performance during night
morning
Individuals with shorter rhythm tend to be _____ persons Peak performance during day
Geen's theory of extraversion/introversion
Introverts and extraverts choose different levels of stimulation, but equivalent in arousal under chosen stimulation Introverts and extraverts perform task best under their chosen stimulation level, poor when performing under a stimulation level chosen by other group
eysenk's theory of extraversion/introversion
Introverts have a higher level than extraverts of activity in the brain's ascending reticular activating system (ARAS) People strive to keep ARAS activity at optimal level—introverts work to decrease and avoid stimulation; extraverts work to increase and seek out stimulation Research indicates that introverts and extraverts are NOT at different resting levels, but introverts ARE more reactive to moderate levels of stimulation than extraverts This work led Eysenck to revise his theory—the difference between introverts and extraverts lies in arousability, not in baseline arousal When given a choice, extraverts prefer higher levels of stimulation than introverts
Brain Asymmetry and Affective Style
Left and right sides of the brain are specialized, with asymmetry in control of psychological functions Using EEG, can measure brain waves, such as alpha wave—an inverse indicator of brain activity Left frontal hemisphere is more active than the right when a person is experiencing pleasant emotions; right is more active than left with unpleasant emotions Patterns replicated in adults, children, and infants relates to emotional style Research indicates that the tendency to exhibit asymmetry (favoring left over right, or right over left activation) is a stable individual characteristic Dispositionally positive persons show greater left frontal EEG activity (positive people) Dispositionally negative persons show greater right frontal EEG activity Conclusion: Person's affective lifestyle may have origins in, or be predicted by a pattern of asymmetry in frontal brain activation
Extraversion-Introversion
Measured by Eysenck Personality Questionnaire (EPQ) High extraversion: Talkative, outgoing, likes meeting new people and going to new places, active, bored easily, hates routine Low extraversion: Quiet, withdrawn, prefers being alone or with a few friends to large crowds, prefers routines, prefers familiar to unexpected
Electrodermal Activity (EDA): Skin Conductance
Most obtained by electrodes or sensors placed on the skin surface Advantage: Noninvasive, no discomfort Disadvantage: Movement constrained Electrodermal activity—due to increased sweat with arousal, skin conductance of electricity increases Can measure responses to various stimuli, including sudden noises, emotionally charged pictures, pain, anxiety, fear, guilt Some people show EDA in the absence of external stimuli—associated with anxiety and neuroticism
Sensitivity to Reward and Punishment
Personality based on two hypothesized brain systems BAS and BIS
Behavioral Inhibition System (BIS)
Responsive to cues to punishment, frustration, uncertainty, and motivates ceasing, inhibiting, or avoidance behavior Active BIS produces anxiety
Behavioral Activation System (BAS):
Responsive to incentives (cues to reward) and regulates approach behavior active BAS produces impulsivity
summary
Study of personality can be approached biologically Two ways to think about how physiological variables are useful in personality theory and research... Use physiological measures as variables that may be correlated with personality traits View physiological events as providing causal substrate for personality trait
Sensation Seeking
Tendency to seek out thrilling, exciting activities, take risks, avoid boredom Early sensory deprivation research Hebb's theory of optimal level of arousal
Positron emission tomography (PET)
brian imaging technique that measures blood flow to active areas of the brain
Gray's model of reward and punishment system
impulsive people do not learn well from punishment because of weak BIS; learn better from reward—supported by research
Physiological basis for sensation seeking
neurotransmitters and Monoamine Oxidase (MAO) Too little MAO = too much neurotransmitter Too much MAO = too little neurotransmitter (common in depression) High sensation seekers have low levels of MAO, producing a need for stimulation to reach the optimal level of arousal MAO is like a brake to stop sensation
