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.     

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.     

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.     

The risk of dental caries in extraverts

It has been demonstrated that extraverts have a lower saliva secretion rate than introverts. Furthermore, extraverts as well as subjects with high P-scores on the EPQ have been demonstrated to have a more pronounced risk-taking behaviour, possibly including a tendency to neglect health care programs. Thus it was hypothesised that extraverts and possibly also subjects with high P-scores would have an increased risk of caries. The Swedish translation of the 97 items JEPQ was administered to 101 15-year-old adolescents controlled at the annual dental status health control. Extraverts were found to have significantly more earlier caries and significantly more total caries and a tendency towards higher values in initial and manifest caries. Subjects with high P-scores were found to have significantly more manifest caries. No significant relationships were found between the frequency of caries and the N- or L-scales in the JEPQ.     

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.     

在不同事件率条件下人格倾向类型对认知性警戒的影响

本研究采用两种事件率 ,考察了人格倾向类型对认知性警戒的影响。实验结果表明 :(1 )事件率是影响作业绩效的一个重要因素。事件率与人格倾向存在着交互作用。 (2 )认知性警戒作业的应激效应与事件率有关 ,随着事件率的上升 ,受试者在作业过程中的应激水平明显增高。 (3 )根据对被试自觉疲劳的测量结果 ,在认知性警戒作业中 ,内倾者与外倾者间应激水平存在差异。     

Why introverts can't always tell who likes them: multitasking and nonverbal decoding

Despite personality theories suggesting that extraversion correlates with social skill, most studies have not found a positive correlation between extraversion and nonverbal decoding. The authors propose that introverts are less able to multitask and thus are poorer at nonverbal decoding, but only when it is a secondary task. Prior research has uniformly extracted the nonverbal decoding from its multitasking context and, consequently, never tested this hypothesis. In Studies 1-3, introverts exhibited a nonverbal decoding deficit, relative to extraverts, but only when decoding was a secondary rather than a primary task within a multitasking context. In Study 4, extraversion was found to correlate with central executive efficiency (r = .42) but not with storage capacity (r = .04). These results are discussed in terms of arousal theories of extraversion and the role of catecholamines (dopamine and norepinephrine) in prefrontal function.     

认知操作、认知方式与外倾性人格特质的关系

对28名外倾被试和28名内倾被试进行实验性认知测试,以考察认知操作、认知方式与外倾性人格特质的关系。结果表明,内外倾被试在含有社会认知操作、非社会认知操作的认知任务的测试总分上没有差异,而在社会认知一非社会认知方式的评价分数上存在显著差异。外倾被试更多地倾向于社会认知型认知方式,内倾被试更多地倾向于非社会认知型认知方式。研究结果支持了外倾性与智力关系的假设：外倾性与社会认知一非社会认知的认知方式存在相关关系,而与认知操作测试总分无关。     

Extraversion-introversion and heat-stress tolerance

Ten Ss were tested under heat-stress conditions, during which their physiological stress was measured. Before commencement of the experiment, the Ss' level of extraversion was measured, as well as the meaning they assigned to the situation and the subjective probability of success they gave themselves. It was found that extraverts assigned significantly more positive meaning to the heat-stress situation than introverts, and they tended to estimate their probability of success as higher than did the introverts. However, extraverts tended to suffer from higher physiological stress than introverts, where the main cause for that seemed to be their higher expectations resulting from the positive meaning assigned by them to the heat-stress situation.     

The interactive effect of personality, time of day, and caffeine: a test of the arousal model

The personality dimension of introversion/extraversion is one of the few personality dimensions that can be reliably identified from study to study and investigator to investigator. The importance of this demension within personality theory is due both to the stability of the trait and the influential theory of H. J. Eysenck. The basic assumption in Eysenck's theory of introversion/extraversion is that the personality differences between introverts and extraverts reflect some basic difference in the resting level of cortical arousal or activation. Assuming that there is a curvilinear relationship (an inverted U) between levels of stress and performance leads to a test of this arousal theory. That is, moderate increases in stress should hinder the performance of introverts who are presumably already highly aroused. However, the same moderate increase in stress might help the performance of the presumably underaroused extraverts. Revelle, Amaral, and Turriff reported that the administration of moderate doses of caffeine hindered the performance of introverts and helped the performance of extraverts on a cognitive task similar to the verbal test of the Graduate Record Examination. Assuming that caffeine increases arousal, this interaction between introversion/extraversion and drug condition supports Eysenck's theory. This interaction was explored in a series of experiments designed to replicate, extend, and test the generality of the original finding. The interaction between personality and drug condition was replicated and extended to additional cognitive performance tasks. However, these interactions were affected by time of day and stage of practice, and the subscales of introversion/extraversion, impulsivity, and sociability, were differentially affected. In the morning of the first day, low impulsives were hindered and high impulsives helped by caffeine. This pattern reversed in the evening of the first day, and it reversed again in the evening of Day 2. We concluded that the results from the first day of testing require a revision of Eysenck's theory. Instead of a stable difference in arousal between low and high impulsives, it appeared that these groups differed in the phase of their diurnal arousal rhythms. The result is that low impulsives are more aroused in the morning and less aroused in the evening than are the high impulsives. A variety of peripheral or strategic explanations (differences in caffeine consumption, guessing strategies, distraction, etc.) for the observed performance increments and decrements were proposed and tentatively rejected. It seems probable that some fundamental change in the efficiency with which information is processes is responsible for these performance changes.     

Extraversion and positive affect: A day reconstruction study of person–environment transactions

Extraversion is robustly correlated with positive affect, but the reasons for this correlation remain unclear. One possibility is that extraverts and introverts both enjoy interacting with others, but extraverts do so more frequently. Another possibility is that extraverts enjoy social interactions more. Both hypotheses were tested using the Day Reconstruction Method. Subjects reported on interactions with others and positive affect experienced during all of the episodes from a single day. Results were consistent with the first hypothesis: the relation between extraversion and positive affect was partially mediated by extraverts’ greater social participation. The findings support a transactional approach to personality, in which traits like extraversion are seen as styles of actively engaging with the environment.     

The relation between temperament and rate of temporal discounting

The present study examines the relationship between several temperamental traits (sensation seeking, extraversion–introversion, and impulsivity) and rate of temporal discounting, that is the rate of decrease in the subjective value of a reward as the delay to its receipt increases. Participants made choices between hypothetical monetary rewards that could be obtained immediately or after a specified delay. Temporal discounting functions were calculated and differences in rate of discounting between different groups were evaluated. For all groups of participants, hyperbolic discounting functions described well the decreases in subjective value with delay (R² ranged from 0.700 to 0.985). The rate of discounting was equivalent in high and low sensation seekers. However, both extraverts and high impulsive individuals showed higher temporal discounting rates than introverts and low impulsive individuals. The relationship between temperament and temporal discounting may be related to differences in time perception and/or to differences in susceptibility to rewards in extraverts versus introverts and in high- versus low-impulsive individuals.     

Extraversion and task performance: A fresh look through the workload history lens

This study manipulated workload levels and used a technique examining workload history to test Eysenck’s (1967) theory of extraversion. Participants consisted of 71 undergraduates who had been selected from a larger pool that had completed the Eysenck Personality Inventory. Participants performed an auditory vigilance task while percent correct data were recorded. A repeated measures ANOVA was conducted and results indicated that extraverts and introverts respond differently to a sudden decrease in workload level. Specifically, a sudden decrease in workload level resulted in an immediate significant decrement in correct responses for extraverts while the decrement for introverts was minimal. Limitations were discussed and implications for future research were addressed.     

Extraversion and arousal: Effects of attentional conditions on electrodermal activity

Recent work has demonstrated that introverts show arousal decrements with increasing caffeine dosages under nonsignal conditions, but reverse this pattern under signal conditions. Other work, particularly in the areas of vigilance and memory, has pointed to greater attentiveness in introverts than extraverts. It was therefore hypothesized that the two groups would respond differentially under signal and nonsignal conditions as a function of attentional variations. The present study tested introverts and extraverts in a habituation paradigm involving systematic manipulation of signal and attentional conditions. Half of each personality group was randomly assigned to a distraction condition, the other half to an attending condition. Each S received two blocks of 19 habituation trials, a test stimulus and a dishabituation stimulus. In one of the two trial blocks, each stimulus was preceded by an auditory preparatory signal. Results showed that introverts gave larger SCRs, had higher SCLs, and showed greater dishabituation than extraverts. The signal reduced responding significantly more in introverts than in extraverts, and introverts were less affected by the distraction condition than were extraverts. Finally, extraverts showed more rapid habituation under nonsignal conditions and the signal produced a greater increase in habituation rate for introverts than for extraverts. Results were basically supportive of hypotheses derived from the Eysenck theory.     

Want a tip? Service performance as a function of emotion regulation and extraversion

Surface acting and deep acting with customers are strategies for service performance, but evidence for their effectiveness is limited and mixed. We propose that deep acting is an effective strategy for most employees, whereas surface acting's effect on performance effectiveness depends on employee extraversion. In Study 1, restaurant servers who tended to use deep acting exceeded their customers' expectations and had greater financial gains (i.e., tips) regardless of extraversion, whereas surface acting improved tips only for extraverts, not for introverts. In Study 2, a call center simulation, deep acting improved emotional performance and increased the likelihood of extrarole service behavior beyond the direct and interactive effects of extraversion and other Big Five traits. In contrast, surface acting reduced emotional performance for introverts and not extraverts, but only during the extrarole interaction. We discuss implications for incorporating traits into emotional labor research and practice.     

The effect of background music and noise on the cognitive test performance of introverts and extraverts

Previous research has found that the performance of introverts on complex cognitive tasks is more negatively affected by distracters, e.g. music and background noise, than the performance of extraverts. The present study extends previous research by examining whether or not background noise would prove to be as distracting as music. In the presence of silence, background UK garage music and background noise, 118 female secondary school students carried out three cognitive tests. It was predicted that introverts would do less well on all of the tasks than extraverts in the presence of music and noise but in silence performance would be the same. A significant interaction was found on all three of the tasks. It was also predicted that there would be a main effect of background sound: Performance would be worse in the presence of music and noise than silence. Results confirmed this prediction with one exception. This study also found a positive correlation between extraversion and intelligence, the implications of which are also discussed. The findings support the Eysenckian hypothesis of the difference in optimum cortical arousal in introverts and extraverts. Copyright © 2010 John Wiley & Sons, Ltd.     

NMDA receptor activity and the transmission of sensory input into motor output in introverts and extraverts.

Recent research suggests that individual differences in brain dopamine functioning may be related to the personality dimension of extraversion. The major goal of the present study was to answer the question of whether a pharmacologically induced change in glutamatergic NMDA receptor activity would also differentially affect the transmission of sensory input into motor out-put in introverts and extraverts. Therefore, in a double-blind within-subjects design, either 30 mg of the NMDA receptor antagonist memantine or placebo were administered to 48 healthy male volunteers before performing a choice reaction-time task. In introverts, memantine caused a pronounced increase in lift-off time (i.e., the time required to lift the finger from a home button) compared to that in extraverts, whereas movement time (i.e., the time required to move the finger from the home button to a response button) was decreased in both groups. The pattern of results suggests that extraversion-related differential sensitivity to pharmacologically induced changes in NMDA receptor activity is limited to functions that involve an interaction between the glutamatergic and dopaminergic systems.     

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’.     

Color preferences, extraversion, and neuroticism of art students.

Color preferences of 190 art students (G?tz & G?tz, 1974, 1975) were compared with the corresponding scores on extraversion (E) and neuroticism (N). It was found that the preferences of a group of 27 highly gifted young artists were different from preferences of average and less gifted Ss who had little or no artistic practice. In the latter group extraverts and ambiverts mainly preferred primary and secondary colors (light clear and dark clear tones included), while introverts preferred tertiary colors (earth colors) and achromatics. However, in the group of highly gifted Ss no significant differences between positive and negative rankings in both color categories were found. Neuroticism had no effect on color preferences; this holds for introverts and extraverts and for each single color.     

Do extraverts get more bang for the buck? Refining the affective-reactivity hypothesis of extraversion

One of the most robust observations in personality and emotion research is the finding that extraverts are happier than introverts. Some theorists have attributed this to differential reactivity of the brain reward system, which is central to many biologically inspired models of extraversion. This affective-reactivity hypothesis, which suggests that extraverts should be more susceptible to the induction of positive affect, has so far received very mixed empirical support. In this article, we consider a more biologically plausible account of extraverts' affective-reactivity. Over 5 experiments, we demonstrate that extraverts show greater affective-reactivity only in response to clearly appetitive stimuli and situations (e.g., where rewards are being pursued). Conversely, after merely pleasant stimuli and situations (without any reward-approach element), extraverts and introverts respond similarly. We also show that it is specifically activated affect (e.g., feelings of alertness), rather than pleasantly valenced affect (e.g., feelings of contentment), that characterizes the affective-reactivity of extraverts. Such reactions may potentially facilitate the reward-seeking behavior associated with extraversion, but they seem unlikely to explain the broadly happy disposition of extraverts.