Physiological Approaches to Personality Chapter 7 Physiological Approaches to Personality

A Physiological Approach to Personality The case of Elliot (p. 187-188) is a good example of how changes in the brain can change personality Diminished ability to inhibit or control one’s impulses is one of the most common changes in personality following brain injury (____________ ______________________________________________) Often associated with spontaneous outbursts, sudden changes in mood, and episodes of aggression Classic example: Phineas Gage

A Physiological Approach to Personality An advantage of the physiological approach is that physiological characteristics can be measured mechanically and reliably e.g., nervous system, cardiac system Assumes that differences in physiological characteristics are related to differences in important personality characteristics and behavior patterns Consider: ____________________________________ ______________________________________________________________________________________________

Physiologically Based Theories of Personality Extraversion-Introversion Sensitivity to Reward and Punishment Sensation Seeking Morningness-Eveningness

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likes meeting new people and going to new places, active, bored easily, hates routine Low extraversion: Quiet, withdrawn, prefers being alone or with a few friends to large crowds, prefers routines, prefers familiar to unexpected

Extraversion-Introversion Eysenck’s theory Introverts have a higher level than extraverts of activity in the brain’s _______________________________________ _____________________________________________________ People strive to keep ARAS activity at optimal level—introverts work to decrease and avoid stimulation; extraverts work to increase and seek out stimulation ____________________________________________________________________________________________________________________________________________________________________________________________________________ This work led Eysenck to revise his theory—the difference between introverts and extraverts lies in ___________________________________________________

Extraversion-Introversion Eysenck’s theory When given a choice, extraverts prefer higher levels of stimulation than introverts Geen (1984): ____________________________________________________________________________________________________________________________________________________________ Introverts and extraverts perform tasks best under their chosen stimulation level, but poor when performing under a stimulation level chosen by other group

Sensitivity to Reward and Punishment Personality based on two hypothesized brain systems (Gray, 1972, 1990): Behavioral Activation System (BAS): ________________________________________________________________________________________ Behavioral Inhibition System (BIS): ____________________________________________________________________________________________________________________________________ ____________________________________________________________________________________

Sensitivity to Reward and Punishment Integration with Eysenck’s model: Impulsive = high extraversion, moderate neuroticism Anxious = moderate introversion, high neuroticism ______________________________________________________________________________________________________________________________

Sensation Seeking Sensation seeking – _________________________ ______________________________________________________________________________________________ Sensory deprivation research Put in a small chamber where there is no light, no sound, and minimal tactile sensations Relaxed  Bored  Anxious  Hallucinate People in such environments are motivated to acquire any sensory input

Sensation Seeking Hebb’s theory of optimal level of arousal ______________________________________________________________________________________________ If underaroused, an increase in arousal is rewarding If overaroused, a decrease in arousal is rewarding In sum, people need stimulation and sensory input

Sensation Seeking Zuckerman High sensation seekers are less tolerant of sensory deprivation ____________________________________________________________________________________________________ Zuckerman’s Sensation Seeking Scale Measures the extent to which a person needs novel or exciting experiences and enjoys the thrills and excitement associated with them *Moderate positive correlation between extraversion and sensation seeking

Sensation Seeking Physiological basis for sensation seeking Monoamine Oxidase (MAO) Enzyme that maintains a proper level of neurotransmitters (breaks down neurotransmitter after it has allowed a nerve impulse to pass) Too little MAO = too much neurotransmitter Too much MAO = too little neurotransmitter _________________________________________________________________________________________________________________________________________________________ Thus, perhaps sensation seeking is caused by, or is maintained by, having high levels of neurotransmitters in the nervous system Have too little of the “biochemical brakes”

Sensation Seeking _______________________________________________________________________________________________________________________________________ May be associated with a specific brain area – prefrontal cortex – associated with the ability to anticipate consequences and to engage in self-regulation Similar mechanisms to substance and alcohol abuse

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—_______________________ (e.g., body temperature, endocrine secretion rates) But wide individual differences are in the circadian rhythm, identified through temporal isolation studies Live in an environment controlled by the experimenter with respect to time cues No windows, no regularly scheduled meals, no access to live television or radio ___________________ – no time cues to influence behavior or biology

Morningness-Eveningness Individuals with shorter circadian rhythms hit peak body temperature and alertness earlier in day, get sleepy earlier, than individuals with longer rhythm ___________________________________________________________________________________________________________________________________________________ Cross-cultural replication and documentation of stability for the morningness-eveningness characteristic

Summary and Evaluation 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