1. Psychology 305B: Theories of Personality
Lecture 7
Psychology 305

2. Scoring Your Questionnaire
1. Reverse score items 10 and 19.
Sum the following items:
1, 4, 7, 10, 12, 15, 19
2, 3, 5, 6, 8
9, 11, 13, 18
14, 16, 17, 20
Psychology 305

3. Questions That Will be Answered in Today’s Lecture
Biological Perspective on Personality:
Physiological Approach (continued)
3. What physiological measures are commonly used in contemporary personality research?
4. What does contemporary research suggest about the physiological basis of (a) extraversion, (b) sensitivity to reward and punishment, and (c) sensation seeking?
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4. What physiological measures are commonly used in
contemporary personality research?
Four physiological measures are of particular interest to contemporary personality psychologists:
1. Measures of Electrodermal Activity (Skin Conductance)
Assess the concentration of water or sweat on the palms.
Provide a direct measure sympathetic nervous system activity (i.e., the fight-or-flight response).
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5. Typically, this technique involves placing 2
Typically, this technique involves placing 2 electrodes on the palm of one hand. A very low voltage of electricity is sent through one electrode into the skin. The amount of electricity detected at the second electrode assesses how well the skin is conducting electricity.
E.g., Research assessing electrodermal activity suggests that people who are high in neuroticism have chronically activated sympathetic nervous systems.
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6. 2. Measures of Cardiovascular Activity
Include measures of blood pressure and heart rate.
Blood pressure and heart rate provide direct measures of sympathetic nervous system activity.
E.g., Research assessing cardiovascular activity suggests that people who are characterized by impatience, competitiveness, and hostility (i.e., the “Type A” personality) experience chronic cardiac reactivity, a condition that contributes to heart disease.
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7. 3. Measures of Brain Activity
Include positron emission tomography (PET) and functional magnetic resonance imaging (fMRI).
PET involves administering a radioactive substance to the participant. The radioactive substance is typically attached to glucose. The PET scanner detects the emission of positrons from the radioactive substance, thereby indicating where glucose consumption and physiological activity is greatest.
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8. PET Image of the Brain

9. fMRI uses radio waves and strong magnetic fields to
fMRI uses radio waves and strong magnetic fields to produce an image of physiological activity. fMRI identifies regions in the brain where blood vessels are expanded and extra oxygen is being delivered, thereby indicating where physiological activity is greatest.
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10. fMRI Image of the Brain

11. E. g. , Research employing fMRI suggests that
E.g., Research employing fMRI suggests that individuals who are high in neuroticism experience increased frontal brain activation when exposed to negative images, whereas individuals who are high in extraversion experience increased frontal brain activation when exposed to positive images.
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12. 4. Biochemical Measures of Blood and Saliva
Assess hormone levels (e.g., testosterone) and enzyme levels (e.g., monoamine oxidase).
E.g., Research suggests that shy children have relatively high levels of cortisol in their systems. Cortisol is a byproduct of noradrenaline, a hormone released under stress.
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13. What does contemporary research suggest about
the physiological basis of extraversion?
Eysenck (1967) proposed a physiological theory to account for individual differences in extraversion.
According to Eysenck’s theory, the ascending reticular activating system (ARAS) plays a critical role in determining levels of extraversion.
The ARAS is a structure in the brainstem that controls cortical arousal. High levels of ARAS activity result in high levels of cortical arousal. Low levels of ARAS activity result in low levels of cortical arousal.
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14. Eysenck suggested that introverts have relatively high
Eysenck suggested that introverts have relatively high levels of ARAS activity and, therefore, relatively high levels of cortical arousal.
In order to avoid further arousal, introverts restrain themselves, seek low-stimulation settings, and avoid social interactions that may exacerbate their often over stimulated condition.
That is, introverts engage in activities that regulate their levels of arousal downward.
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15. In contrast, Eysenck suggested that extraverts have
In contrast, Eysenck suggested that extraverts have relatively low levels of ARAS activity and, therefore, relatively low levels of cortical arousal.
In order to enhance their levels of arousal, extraverts seek high-stimulation experiences, settings, and social interactions.
That is, extraverts engage in activities that regulate their levels of arousal upward.
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16. Research has provided support for Eysenck’s theory.
E.g., Brebner & Cooper (1978)
Found that extraverts pushed a button at a higher rate than introverts when pushing the button resulted in a change in the visual environment.
E.g., Campbell & Hawley (1982)
Found that extraverts were more likely to study in noisy reading rooms, whereas introverts were more likely to study in quiet reading rooms.
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17. E.g., Geen (1984) Found the following:
(a) Extraverts preferred to undertake a learning task under noisier conditions than introverts.
(b) When extraverts were asked to complete the learning task under the noise level preferred by introverts, they became bored (i.e., under aroused) and their performance deteriorated.
(c) When introverts were asked to complete the learning task under the noise level preferred by extraverts, they became distressed (i.e., over aroused) and their performance deteriorated.
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18. What does contemporary research suggest about the
physiological basis of sensitivity to reward and punishment?
Gray (1972, 1990) proposed a physiological theory to account for individual differences in sensitivity to reward and punishment: Reinforcement Sensitivity Theory.
Gray’s theory hypothesizes that there are two systems within the brain that respond to reward and punishment: The behavioural activation system (BAS) and the behavioural inhibition system (BIS).
The BAS is based in the left prefrontal cortex. The BIS is based in the right prefrontal cortex.
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19. Gray maintained that the BAS is responsive to rewards
Gray maintained that the BAS is responsive to rewards or incentives, generates positive emotions (e.g., eagerness, excitement), and regulates “approach” behaviours.
E.g., In a child, the BAS would recognize music emanating from an ice cream truck as a reward cue, would generate positive emotions in response to that cue, and would create an urge to run to the truck.
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20. The BAS appears to be linked to dopamine levels.
Gray believed that the BAS is responsible for the personality dimension of extraversion or impulsivity.
The BAS appears to be linked to dopamine levels.
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21. In contrast, Gray maintained that the BIS is responsive
In contrast, Gray maintained that the BIS is responsive to punishment or frustration, generates negative emotions (e.g., anxiety, fear), and regulates “avoidance” behaviours.
E.g., In a child who is shouting, the BIS would recognize a mother’s stern glance as a punishment cue, would generate negative emotions in response to that cue, and would inhibit further shouting.
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22. The BIS appears to be linked to serotonin levels.
Gray believed that the BIS is responsible for the personality dimension of neuroticism or anxiety.
The BIS appears to be linked to serotonin levels.
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23. BAS/BIS Sensitivity Survey
Score on items:
1, 4, 7, 10, 12, 15, 19 = BIS Sensitivity
2, 3, 5, 6, 8 = BAS Sensitivity: Reward Responsiveness
9, 11, 13, 18 = BAS Sensitivity: Drive
14, 16, 17, 20 = BAS Sensitivity: Fun Seeking
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24. The 3 BAS sensitivity subscales are as follows.
Reward responsiveness: Assesses how responsive one is to the occurrence or anticipation of rewards.
Drive: Assesses the persistence with which one pursues desired goals.
Fun seeking: Assesses one’s desire for new rewards and one’s willingness to approach potentially rewarding events on the spur of the moment.
Psychology 305

25. BAS Sensitivity: Reward Responsiveness 17.59 2.14
BAS/BIS Sensitivity Survey Means and Standard Deviations (Carver & White, 1994), N = 732
Mean SD
BIS Sensitivity
BAS Sensitivity: Reward
Responsiveness
BAS Sensitivity: Drive
BAS Sensitivity: Fun Seeking
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26. Research has provided support for Gray’s hypotheses.
Gray integrated his theory with learning theory and generated the following hypotheses.
(a) People who have a sensitive BAS are more likely to learn when they are rewarded than when they are punished.
(b) People who have a sensitive BIS are more likely to learn when they are punished than when they are rewarded.
Research has provided support for Gray’s hypotheses.
Psychology 305

27. Had participants engage in a learning task.
E.g., Larsen et al. (2003)
Had participants engage in a learning task.
Some participants were rewarded for each correct response, earning $5 over the course of the experiment.
Other participants were punished for each incorrect response; they were given $10 and lost $5 over the course of the experiment.
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28. Found that:
(a) participants who obtained high BAS sensitivity scores (i.e., were higher in extraversion/ impulsivity) performed better when they worked for reward.
(b) participants who obtained high BIS sensitivity scores (i.e., were higher in neuroticism/anxiety) performed better when they worked to avoid punishment.
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29. What does contemporary research suggest about
the physiological basis of sensation seeking?
Sensation seeking refers to the tendency to seek out varied, novel activities that are both exciting and risky.
The term “sensation seeking” (SS) was coined by Marvin Zuckerman (1965), who developed the Sensation Seeking Scale to measure this characteristic.
Psychology 305

30. Examples of Items from the Sensation Seeking Scale
I sometimes like to do things that are a little frightening.
A sensible person avoids activities that are dangerous. *
I like to have new and exciting experiences and sensations even if they are frightening, unconventional, or illegal.
Almost everything enjoyable is illegal or immoral.
I get bored seeing the same old faces.
I like the comfortable familiarity of everyday friends. *
* Reverse-scored items.
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31. Zuckerman (1991) maintains that SS is physiologically. based
Zuckerman (1991) maintains that SS is physiologically based. Consistent with this assertion, he found that individuals who were high in SS had relatively low levels of monoamine oxidase (MAO) in their blood.
MAO is an enzyme that breaks down neurotransmitters. Neurotransmitters are chemicals that enable the transmission of nerve impulses from one cell to another.
Psychology 305

32. MAO breaks down neurotransmitters in the synaptic cleft.

33. Thus, MAO act as a “brake,” diminishing or inhibiting
Thus, MAO act as a “brake,” diminishing or inhibiting neurotransmission.
Zuckerman maintains that the low levels of MAO in sensation seekers results in relatively high levels of the neurotransmitter dopamine within the nervous system. The high levels of dopamine, in turn, cause a “disinhibition” of the nervous system, resulting in less control over behaviour, thought, and emotion.
Psychology 305

34. Questions That Were Answered in Today’s Lecture
Biological Perspective on Personality:
Physiological Approach (continued)
3. What physiological measures are commonly used in contemporary personality research?
4. What does contemporary research suggest about the physiological basis of (a) extraversion, (b) sensitivity to reward and punishment, and (c) sensation seeking?
Psychology 305

35. Jeffrey Dahmer,

36. Analysis of the Personality of a Serial Killer
Jeffrey Dahmer
Discussion Questions
How would you expect Jeffrey Dahmer to score on the personality dimensions identified by (a) Eysenck, (b) Wiggins, and (c) Big 5 theorists?
2. Can a diathesis-stress model be used to explain the onset of Jeffrey Dahmer’s antisocial behaviour?
3. What needs do you think motivated Jeffrey Dahmer’s behaviour? Consider both Murray’s needs and the “Big Three.”
Psychology 305

37. Discussion Questions, continued
Can evolutionary psychology offer explanations for antisocial behaviour, psychopathy, cannibalism, and/or necrophilia?
5. Which characteristics do you think Jeffrey Dahmer may have inherited?
6. How do you think Jeffrey Dahmer would score on the temperaments identified by Buss and Plomin (i.e., activity level, sociability, and emotionality)?
7. Speculate upon the physiological causes of antisocial personality disorder or psychopathy.
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