Personality & Biology: Research

Question 1

Eysenck favoured a general concept of arousal in which both cortical and autonomic activity operated in a unitary fashion. Unitary theories of arousal however were challenged. Why?

Answer 1

The so-called physiological indicators of arousal are often if at all correlated. Thus, this lecture focuses on the central nervous system and the autonomic nervous system.

Question 2

What are Basal measures?

Answer 2

Basal measures index physiological activity under at rest conditions, where there is minimal stimulation.

Question 3

What are phasic measures?

Answer 3

Phasic measures index the immediate physiological response to an event (task or stimulus).

Question 4

When regarding Eysenck’s arousal theory of extraversion, why is the distinction between Basal measures and Phasic measures quite important?

Answer 4

When Basal measures used, there is very little support for Eysenck’s position that extraverts have lower cortical arousal than introvert.
Phasic measures though do provide some support for Eysenck’s theory. Introverts do show greater Phasic activity to stimuli than extraverts.

Question 5

In terms of the central nervous system, what type if studies are we concerned with?

Answer 5

EEG studies
- Basal measures: EEG frequency bands
- Phasic measures: evoked potentials
Functional imaging studies

Question 6

Electroencephalogram (EEG) recording electrodes are placed on the scalp according to the?

Answer 6

International 10-20 system
Odd numbers are placed on the left hemisphere & even numbers on the right hemisphere.
Letters stand for the particular cortical region (C = central lobe, P = parietal lobe, T = temporal lobe, O = occipital lobe)

Question 7

EEG frequency bands: describe the 2 basic brain wave patterns identified by Hans Berger in 1929.

Answer 7

Beta waves: 14-30 hz low amplitude, de-synchronised. Found in excited states of arousal.

Alpha waves: 8-13 hz, moderate amplitude, synchronised waves. Occurring primarily in the occipital region during relaxed but awake state. Best obtained when eyes are closed. Any stimulation and Alpha waves are reduced in amplitude or disappear.

Question 8

Later EEG investigations identified Theta waves and Delta waves . Describe both.

Answer 8

Theta waves: 4-7hz high amplitude associated with lower arousal, drowsiness. Are more frequent in the recordings of children.

Delta waves: < 4 hz high amplitude waves that mainly occur during sleep in normal individuals.

Question 9

Drawing on Eysenck’s arousal theory of extraversion, the expectation was that extraverts would show more activity in the low arousal alpha, theta and delta bands. What was the finding?

Answer 9

Weak support by a study showing a correlation of .16 between Delta wave activity and extraversion.
However, overall there is no strong evidence from EEG frequency band studies to suggest there are extraversion related differences In basal cortical arousal levels.

Question 10

Phasic measures: what is a cortical evoked potential?

Answer 10

EP is a momentary change in EEG activity that occurs in response to stimuli.

Question 11

Researchers typically operationalise phasic activity in terms of?

Answer 11

Peak-to-peak amplitudes
e.g. P1-N1 or N1-P2

Question 12

Eysenck’s arousal theory of extraversion suggests that extraverts compared to introverts will show what type of peak-to-peak amplitudes?

Answer 12

Smaller peak-to-peak amplitudes

Question 13

Phasic measures: what type of stimuli is typically used when measuring evoked potentials?

Answer 13

Auditory or visual stimuli

Question 14

Phasic measures: a study by Robert (my lecturer) who searched for individuals who clearly fell into one of the 4 classical temperaments, looked at the evoked potentials of IN (introvert & neurotic) and ES (extraverted & emotionally stable ) individuals when exposed to 3 tone intensities. What did this study find?

Answer 14

Found some support for Eysenck’s arousal theory of extraversion.
- for both temperament groups, the amplitude of the evoked potential response increased as the stimulus intensity increased
- the rate of increase is more pronounced for the introverted melancholic participants. They show a significantly steeper linear trend in the amplitude intensity function.
- Thus, both findings are support Eysenck’s position that the brains of introverts are more reactive to external stimuli than the brain of extraverts.

Question 15

What have studies of phasic measure found overall? Hint 2 points

Answer 15

• Larger evoked potentials have frequently been reported for introverts in response to moderate intensity (70-80dB) auditory stimuli.
• No consistent extraversion related differences in amplitude have been found for visual evoked potentials.

Question 16

Studies testing Gray’s reinforcement sensitivity theory have used auditory and visual evoked potentials to investigate differences in sensitivity to stimuli associated with reward or punishment, but overall studies have shown inconsistent results. Describe one study that did provide support for Gray’s study.

Answer 16

Bartussek et al (1993) tested Gray’s theory using the P2 and N2 amplitudes to auditory toned associated with winning or losing in a gambling task.
- Extraverts had larger P2 evoked potential amplitudes to tones associated with winning.
- Introverts had larger P2 amplitudes to tones associated with losing.

Question 17

Name the following type of functional imaging method; the subject typically receives an injection of radioactive tagged deoyxglucose . Structures of the brain that are most active absorb the most glucose. When the radioactive DG molecules decay, they emit subatomic particles called positrons which can be detected by a scanner.

Answer 17

Positron Emission Tomography (PET)

Question 18

What are 2 disadvantages of PET scans?

Answer 18

• Relatively poor spatial resolution (the blurriness ) of the images
• Poor temporal resolution: the positrons being emitted from the brain must be sampled for a long period of time. Thus, cannot capture moment to moment changes in brain activity & certainly don’t have the ability to capture evoked potentials.

Question 19

What is the imaging technique with the best spatial and temporal resolution?

Answer 19

Functional magnetic resonance imaging (fMRI)

Question 20

What does BOLD stand for (the formal name for fMRI

Answer 20

Blood oxygen level dependent signal

Question 21

How does the temporal resolution of an fMRI compare to a PET scan and can it capture evoked potentials.

Answer 21

fMRI can detect changes in brain activity over much shorter intervals than compared to PET scans. The temporal resolution is down to seconds rather than minutes, but still lacks the temporal milliseconds resolution needed to fully capture evoked potentials

Question 22

The results from functional brain imaging studies (PET & fMRI) are neither consistent nor immediately reconcilable with existing personality theories. Explain.

Answer 22

Many imaging studies have found significant relationships between the limbic system and extraversion. These areas are theoretically associated with;
Neuroticism (Eysenck’s)
Anxiety (Gray’s)

Not extraversion which is associated with the ARAS according to Eysenck’

Question 23

What are the 2 anatomically separate systems of the autonomic nervous system ?

Answer 23

• sympathetic nervous system (fight or flight type response)
• parasympathetic nervous system (maintenance of vital steady state processes)

Question 24

Autonomic nervous system: name and describe a method for collecting Basal and or Phasic measures involving the skin.

Answer 24

Skin conductance studies which involves the electrical reading of 2 electrodes placed on the finger tips. The palms and finger tips contain a high concentration of sweat glands. The sweat acts as a conductor of the electrical signal so as the sweat glands fill with fluid, skin conductance increases.

Question 25

Changes in sweat gland activity are thought to be mediated by sympathetic cholinergic inervation. With Eysenck’s arousal theory in mind, what related skin conductance differences have some researchers explored?

Answer 25

• as the limbic system is implicated some researchers have looked for neuroticism differences in skin conductance measures.
• as the ascending reticular activating system is implicated some researchers have looked for extraversion differences in skin conductance measures.

Question 26

If we are talking about SCL, measured in micro Siemens ( u S), what are we looking at?

Answer 26

Skin conductance level being the base line (Basal measure) level of skin conductance averaged over some specific period of time (eg 3 minutes).

Question 27

Higher skin conductance level is typically associated with?

Answer 27

Higher levels of sympathetic arousal.

Question 28

Studies which have investigated resting Skin conductance level have failed to find difference between extraverts and introverts, although under what type of arousing conditions do introverts typically have higher SKLs than extroverts?

Answer 28

Caffeine and cognitive tasks

Question 29

Studies of subjects high on neuroticism in the general non clinical population have found what in terms of a correlation between N and SCL?

Answer 29

Failed to find any correlation

Question 30

Phasic measures: skin conductance response (SCR) is?

Answer 30

An increase in skin conductance level that occurs in response to a specific stimulus.

Question 31

Phasic measures: non specific (NS-SCR) is?

Answer 31

An increase in skin conductance level that is elicited by an unspecified stimulus, either internal or external, and that is not under the control of the experiment.

Question 32

Phasic measures: how are SCR and NS-SCR typically measured?

Answer 32

Researchers typically focus on the amplitude of the response. The longer the amplitude, the greater the level of phasic activity.

Question 33

You will always record some NS-SCR in an experiment of phasic skin conductance. What causes NS-SCR?

Answer 33

No way to be sure as it could be internal thoughts (worrying that the heater was left on), or reacting to an external observation etc.

Question 34

Phasic measures: in terms of Eysenck’s arousal theory of extraversion, what support have many studies shown?

Answer 34

• introverts have larger SCRs than extraverts to moderate intensity auditory stimuli (75-80 dB)
• introverts have frequently been found to have a higher number of NS-SCRs than extraverts.

Question 35

Heart Rate studies: Basal activity is typically operationalised how?

Answer 35

In terms of beats per minute averaged over say a 3 minute rest period.

Question 36

Heart rate studies: Phasic activity is typically operationalised how?

Answer 36

Beat to beat changed in heart rate during the first 11 seconds after the presentation of a stimulus