1. Physiological Approaches to Personality
Chapter 7
Physiological Approaches to Personality

2. A Physiological Approach to Personality
The case of Elliot (p ) 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

3. 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: ____________________________________
______________________________________________________________________________________________

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

6. 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Quiet, withdrawn, prefers being alone or with a few friends to large crowds, prefers routines, prefers familiar to unexpected

7. 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 ___________________________________________________

8. 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

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

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

11. 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

12. 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

13. 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

15. 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”

16. 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

17. 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 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

18. 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

19. 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