Extraversion and the ability to decode nonverbal communication

This study examined the relationship between extraversion, as measured by the Eysenck Personality Inventory (EPI), and skill at decoding nonverbal forms of communication. Prior research has had mixed success in establishing this relationship. Because extraverts have more experience in social settings than introverts, and because extraverts have a greater desire for sensory stimulation than introverts, it was hypothesized that extraverts would decode nonverbal cues in social interaction more accurately than introverts. The data supported this hypothesis. Extraverts were significantly more accurate in interpreting the meaning of nonverbal communication than introverts; in addition, extraverts were more confident that they were accurate decoders than introverts. The results are discussed in terms of cognitive processing style: the ‘extravert advantage’ in decoding nonverbal communication may be due to extraverts' superior attentive/perceptual skills; their superior interpretive/attributional skills; or both. In addition, the results are discussed in terms of methodological issues in the nonverbal decoding literature and their impact on research on extraversion. The nonverbal decoding task used in the present study differed from that of prior research by presenting scenes of natural, spontaneous, dyadic interactions for which an objective criterion for accuracy existed.     

Simple visual reaction time,personality and strength of the nervous system: A signal-detection theory approach

Eysenck (1967) has reviewed evidence which suggests that introverts have a higher level of arousal than extraverts. Moreover, Gray (1967) has proposed that introverts have weak nervous systems, in the Russian terminology. Studies of simple reaction time such as that of Mangan and Farmer (1967) have posed problems for these views, but it is suggested that this may have been due to criterion differences between introverts and extraverts. In the present study a simple visual reaction-time task and a signal-detection task were conducted side by side. No significant differences between introverts and extraverts were found in measures of strength derived from the former, or measures of criterion derived from the latter. However, high N Ss were found to have a significantly lower value for Nebylitsyn's index of the slope of the reaction time/stimulus intensity function, thus supporting the view that high N Ss have relatively weak nervous systems.     

Effects of noise on sensitivity of introverts and extraverts to signals in a vigilance task

Forty Ss, previously classified as introverts or extraverts on the basis of scores on the Eysenck Personality Inventory, performed a visual vigilance task while being stimulated with noise at an intensity level of either 65 or 85 dB. Introverts given noise of 65 dB intensity showed an improvement in detection rate across trials, whereas introverts given noise of 85 dB intensity showed a decline in detection rate. Extraverts responded to noise of 65 dB intensity with a slight decrease in detection rate, but showed an improvement in detection over trials when noise of 85 dB intensity was given. When noise of the lower intensity was given, introverts showed greater sensitivity to signals than extraverts. When noise of the higher intensity was given, introverts and extraverts were equal in sensitivity. The results are discussed in terms of a hypothesized relationship between stimulation and arousal, with E-I as a moderator variable.     

The role of personality in crowding research

An analysis of variance was carried out on Ss who were tested with a letter-cancellation task under four experimental conditions, two levels each of crowding and disconfirmation of expectancy. Eight types of Ss were distinguished based on sex and high or low scores on E and N. The crowding situation and disconfirmation of expectancy was found to affect extraverts significantly more than introverts, as predicted by the Brebner-Cooper model. It was confirmed that personality is an important variable in crowding research.     

Expectation of success following noncontingent punishment in introverts and extraverts

Recent findings indicate that extraverts are more likely than introverts to continue responding in the face of punishment and frustrating nonreward (Newman & Kosson, 1984; Tiggemann, Winefield, & Brebner, 1982). The current study investigates whether extraverts' expectations for success are, similarly, resistant to interruption and alteration. To test this hypothesis, 50 introverted and 50 extraverted male undergraduates were exposed to pretreatment with either a 50% level of noncontingent reward or a 50% level of noncontingent punishment. As predicted, there were significant Group X Pretreatment interactions on all dependent measures. In comparison to those introverts who received the punishment pretreatment, extraverts exposed to the same pretreatment placed larger wagers on their ability to succeed, and reported higher levels of perceived control. In addition, relative to their estimates for the pretreatment task, extraverts exposed to noncontingent punishment increased their expectation for success, whereas introverts exposed to noncontingent punishment decreased their performance expectations. No differences were observed between the two groups following pretreatment with noncontingent reward. The results suggest that extraverts are characterized by a distinctive reaction to punishment involving response facilitation as opposed to response inhibition.     

Introversion-extraversion,tempo, and guided imagery

This research tested the hypotheses that (a) introverts would produce more vivid imagery than would extraverts, and (b) introverts would produce better mental imagery if the background auditory tempo was slow, and extraverts would produce better mental imagery of the background auditory tempo was fast. Participants (N=240) were classified as introverts or extraverts and were randomly assigned one of three tempo conditions: slow, fast, or none. They were instructed to form mental images while listening individually to one of two stories. Clicks (slow or fast) sounded in the background during the stories. All participants then completed detailed questionnaires about the vividness of their mental imagery. Analysis showed that introverts reported significantly more vividness in their imagery than did extraverts. The hypothesized interaction between personality and tempo was not found. Implications were drawn for therapeutic applications of mental imagery.     

Extraversion and reactions to cognitive inconsistency

Two studies are reported which test the hypothesis that extraverts are more tolerant of cognitive inconsistency than are introverts. The first study tested this prediction in the context of Heider's balance model. While degree of extraversion did not moderate reactions to imbalance, extraverts did show less aversion to interpersonal disagreement than introverts. When coupled with other recently published data this suggests that extraverts find arousing social situations less aversive than introverts. In support of the main hypothesis, the second experiment showed that extraverts changed their attitudes less than introverts as a result of writing an essay which was counter to their own attitude under conditions where they had high perceived freedom of choice.     

Electrodermal activity and extraversion: Caffeine,preparatory signal and stimulus intensity effects

The Eysenck hypothesis that introverts are more and extraverts less cortically aroused has been supported by the results of most electrodermal studies, though there is some inconsistency in the literature. Further tests of the hypothesis can be carried out using arousal-manipulation paradigms. Some studies have used caffeine or stimulus intensity to increase arousal, as was also the case in the present study. The latter, however, also introduced a preparatory signal, which may be expected under certain conditions, to reduce responses to the stimulus which follows it. Extraverts and introverts were randomly assigned to receive low, medium or high doses of caffeine or a placebo. Each S then heard two sets of tones with the tones in one set preceded by a preparatory signal. Results showed that the preparatory signal reduced phasic amplitudes only at the highest levels of stimulus intensity. Introverts had higher overall SCLs and response magnitudes. In addition, the preparatory signal had little effect on extraverts, but reversed dosage-related response patterns in introverts. Results were supportive of the basic Eysenck arousal hypothesis and also showed that the arousal difference leads to attentional variability between the two groups.     

The influence of introversion/extraversion on the skin conductance response to stress and stimulus intensity

A series of studies compared skin conductance level (SCL) for introverts and extraverts during a series of tones varying in both stimulus intensity (SI) and the amount of stress preceding the tones. When a difficult paired-associate task preceded the tones, both groups were about the same for 83 dB tones but extraverts were much higher at 103 dB, introverts failing to show an increase as a function of SI. There were no differences between the two groups following a simple paired-associate task, both groups showing a similar increase with increased SI. Finally, SCL was higher for introverts than extraverts during tones preceded by a rest period, and this was especially true for the early trials and for lower SI (75 and 83 dB compared with 100 and 103 dB). Taken together, these results suggest that SCL is higher for extraverts at higher levels of arousal but that the reverse is true for lower levels of arousal. This relationship is consistent with the theory that introverts have a “weak nervous system” which develops transmarginal or protective inhibition under stress.     

Attention and personality in augmenting/reducing of visual evoked potentials

Earlier research has shown that extraverts tend to increase their visual evoked potential amplitudes with increasing light intensity (augmenting), while introverts reach their maximum amplitude at lower intensities (reducing). The evoked response has normally been measured from association areas of the brain (at the vertex). The present study measured VEP amplitudes over visual cortex and at the vertex, using four light intensities in two conditions, where attention was either directed towards the light stimuli, or away from them by a concurrent auditory task. Forty subjects were classified as extraverts or introverts based on the Eysenck Personality Inventory. The results show that attention interacted significantly with extraversion. Introverts exhibited a narrower focus of attention, while higher amplitudes and amplitude-intensity functions when attending to the light flashes and lower when distracted. Extraverts showed smaller differences between conditions, indicating a more evenly distributed attention. Higher arousal in introverts is the probable cause of their narrower focus of attention. There were marked differences in the distribution of activity between vertex and occipital cortex. Introverts showed relatively stronger occipital responses and extraverts stronger vertex responses across all intensities and in both conditions. The predisposition for mainly perceptual responses to aversive stimuli in introverts, and for general alerting and motor preparatory responses in extraverts, are interpreted as supportive of Brebner and Cooper's hypothesis that introverts are ‘geared to inspect’ and extraverts are ‘geared to respond’.     

Effects of punishment on response latency in extraverts

Previous findings indicate that in comparison to introverts, extraverts are prone to form responses that are resistant to interruption by punishment. Because the tendency to stop and reflect following punishment may be crucial for subsequent learning, the present study was designed to examine differences between introverts' and extraverts' reactions to punishment using response latency on the trial following punishment as the dependent variable. Sixty-six extraverted and 66 introverted male undergraduates performed a pattern-matching task in which they received noncontingent 50% success and 50% failure feedback under three incentive conditions including reward only, punishment only, or both. As predicted, a significant interaction was found in the both condition, reflecting the tendency of extraverts to respond more quickly and introverts more slowly following punishment feedback than following reward feedback. No significant effects were found in the other two conditions; however, a tendency was noted for extraverts to respond more quickly overall when only reward was given. A second experiment using reward-only and punishment-only feedback replicated this finding and yielded a significant interaction of Group X Condition. The results indicate that in contrast to introverts, extraverts are activated by the availability of reward and, paradoxically, that punishment may facilitate rather than interrupt extraverts' reward seeking behavior.     

Why extraverts are happier than introverts: the role of mood regulation

Three studies tested the hypotheses that extraverts demonstrate better mood maintenance abilities than introverts and that these mood regulation abilities can account for the higher habitual happiness of extraverts. Using self- and peer-rated trait measures, Study 1 provided multimethod evidence that mood maintenance, but not mood repair, accounted for the link between extraversion and pleasant-unpleasant trait mood. Study 2 replicated this finding in a different sample of self-reports. Using a within-subjects design, Study 3 demonstrated that when confronted with an affectively ambivalent situation, extraverts maintained a more positive affect balance than introverts. Habitual mood maintenance mediated the effect of extraversion on pleasant-unpleasant affect change. Taken together, the findings support a self-regulation explanation of the extraversion-pleasant affect link.     

Stimulus- or response-induced excitation. A comparison of the behavior of introverts and extraverts

The tendency to inspect visual material (slides) rather than to respond by pressing a key in an attempt to move on to the next slide, was compared among introverts and extraverts. As predicted from Brebner and Cooper (1974): (1) extraverts inspected the stimuli for a shorter time before making their first response, (2) extraverts made more responses at a faster rate than introverts did, and (3) extraverts produced a significantly higher proportion of runs of accelerating responses.     

The influence of personality on induced depressive mood

An experimental group (n = 40) of normal female undergraduates underwent a Velten type of depressive mood-induction procedure (DMIP) and was compared with a control group (n = 40) which underwent a neutral mood-induction procedure (NMIP). Ss were selected on the basis of scores on the EPI to give a composition in each group of 10 neurotic introverts (NI), 10 neurotic extraverts (NE), 10 stable introverts (SI) and 10 stable extraverts (SE). Depressive mood was assessed before and after each MIP using a measure of psychomotor retardation (writing speed). An ANOVA applied to residualized change scores on the writing-speed measure showed that the DMIP produced a significantly greater depressive effect on mood than the NMIP and that neurotic Ss displayed a significantly greater degree of depressive deficit than stable Ss regardless of type of MIP undertaken. However, a significant interaction between neuroticism and type of MIP showed that neurotic Ss were especially prone to depressive deficits in the DMIP. No effects of extraversion/introversion on susceptibility to depressed mood were detected. The results are discussed in terms of Eysenck and Gray's theory of personality predisposition to depression and it is suggested that the Velten technique may have limitations for the induction of depressed mood.     

Incentive and feedback effects on target detection: A chronometric analysis of Gray's model of temperament

Chronometric (i.e. reaction time) techniques were used to investigate the response, arousal, and attentional components of Gray's (1971, 1982) model of temperament. Subjects were tested in a game context, where each trial consisted of an incentive warning signal (positive or negative), a visual detection target (left or right visual field), and a feedback signal (positive or negative). Several findings were consistent with Gray's proposal that extraverts tend to respond impulsively given signals of reward whereas introverts respond with inhibition given signals of punishment. Extraverts made more overall errors than introverts in the first experiment, and more errors following positive incentive signals in the second study. In addition, introverts responded more slowly than extraverts following negative feedback in the first study. Evidence was also found in support of Gray's proposal that introverts allocate more attention to negative cues than extraverts. Following negative feedback, introverts showed a reflexive attentional bias in favor of negative locations in the second experiment. However, no support was found for the temperamental differences in phasic arousal suggested by Gray's model. The magnitude and build up of general alerting effects following positive and negative incentives were similar for introverts and extraverts.     

Extraversion and emotional reactivity

Six mood induction studies and a meta-analysis were conducted to test 2 models of the extraversion-pleasant affect relation. The affect-level model suggests that extraverts should be happier than introverts in both neutral and positive mood conditions. The reactivity model posits that extraverts react particularly strongly to pleasant stimuli and that they should be happier than introverts only in positive conditions. In all studies, extraverts failed to exhibit greater emotional reactivity when pleasantness items were analyzed. When activated positive affect items were analyzed, results were mixed. The meta-analysis confirmed that there is only a slight reactivity effect overall, and this effect emerges only in activated positive affect items. Furthermore, the meta-analysis showed that the correlation in neutral conditions is strong enough to support the affect-level model.     

Personality,amphetamine and intracranial self-stimulation in rats

The relationship between open-field ambulation and intracranial self-stimulation (ICSS) at the lateral hypothalamic area was studied in rats. A treatment with i.p. saline of d-amphetamine was also applied to the animals prior to ICSS tests. High-ambulatory rats (comparable to human extraverts) showed an equally higher susceptibility to ICSS reward than low-ambulatory rats (comparable to human introverts) with both saline and amphetamine. These findings were interpreted comsidering the ICSS as a strong stimulation which would tend to produce ‘unconditioned inhibition’ much earlier in low-ambulatory rats than high-ambulatory rats thus leading to a better conditioning among the high-ambulatory Ss.     

Actual and stereotyped speech tempos of extraverts and introverts

The study examined the actual speech tempos of extraverts and introverts and stereotyped notions about the tempos of extraverts and introverts. Forty-six female undergraduates were divided on the basis of the Eysenck Extraversion Scale into equal groups of extraverts and introverts. Each was asked to talk in a natural manner about $$ TAT pictures, to talk as if she were an extravert or an introvert, and to speak rapidly or slowly. The results indicate that the actual speech tempo of extraverts is faster than that of introverts and suggest that the stereotypes of the speech rates of extraverts and introverts somewhat exaggerate their actual rates.     

Extraversion and sleep: A psychophysiological study of the arousal hypothesis

In order to examine Eysenck's (1967) hypothesis concerning the relationship between extraversion and arousal, autonomic measures were taken from introverts and extraverts immediately before sleep and during 6 hr of sleep. Introverts and extraverts did not differ in heart rate (HR) or skin-potential response rate (SPR) during the pre-sleep period. A variety of sleep-related measures of arousal provided no strong support for the hypothesis that introverts are more aroused than extraverts. The only consistent autonomic difference between introverts and extraverts during sleep was a tendency for introverts to have higher SPRs in the second 3 hr of the night. The results are discussed in terms of the level of environmental stimulation present in the experimental conditions, and suggestions are made for future sleep studies of the relationship between extraversion and arousal.     

The Costs of Hiding and Faking Emotions: The Case of Extraverts and Introverts

The present study examined the moderation effects of extraversion on the relationships between hiding and faking emotions, perceived satisfaction from intimate relationships, and reported physical health concerns. Four hundred and four Israeli participants, who were all involved in intimate relationships at the time of the study, responded to the Extraversion scale from the Big-Five Inventory, the DEELS to measure hiding and faking emotions, the SELF to assess physical health concerns, and the short version of the ENRICH to evaluate perceived satisfaction with intimate relationships. The mean age was 32.3 years (SD = 8.2); and the average length of time as a couple was 7.8 years (SD = 8.2). Of the participants, 198 were married (48.5%). The findings indicate that the effect of hiding negative emotions was stronger for perceived satisfaction with intimate relationships and physical health concerns than that for faking positive emotions. Extraverts who showed a higher frequency of hiding their negative emotions were significantly less satisfied with their relationships than introverts and they also tended to report more concerns with their physical health. These results were not found when extraverts reported a high frequency of faking positive emotions. These results are discussed in the context of the trait-behavior-concordance model and stress the importance of distinguishing faking from hiding.