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.     

Visual interaction in a group of introverts and extraverts

Ten introverts and 10 extraverts were selected from a student population on the bask of their responses to the E.P.I. The groups contained 5 men and 5 women and were matched for Neuroticism. Each subject took part in two 4-minute conversations, one with a male confederate, one with a female confederate. The same two confederates were used throughout the experiment, and no attempt was made to programme any aspect of their behaviour. Two trained observers, who sat behind a one way screen situated close to the speakers, recorded the visual and speech behaviour of both subject and confederate by means of a four-channel event-recorder. The recordings were made for the last 3 minutes of each interaction. Extraverts Looked more frequently than introverts, but there were no differences between the two groups in the proportions of time spent in Looking and eye-contact, or in the mean length of Looks. Extraverts also spoke more frequently than introverts, a finding which may complement that for the number of Looks. The findings could not be explained by the behaviour of the confederates, since they behaved consistently across the two groups of subjects. The experiment is discussed with particular reference to Mobbs (1968) and Kendon and Cook (1969). Comparisons of methodology are made.     

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.     

Preparatory interval effects on the reaction time performance of introverts and extraverts

This study examined the effect of preparatory interval (PI) lenght on the reaction time (RT) of extraverts (Es) and introverts (Is). In addition to displaying a significantly slower overall mean RT than Es, Is also tended to be more adversely affected by longer PI duration (P = 0.06). That is, unlike Es, Is tended to show a much greater increase in RT to an 8-sec PI duration as compared to a 4-sec PI duration. Examination of the influence of psychoticism (P) and neuroticism (N) effects on the performance of Es and Is indicated that N had no effect for this sample of subjects. However, high levels of P tended to lead to a decrease in the overall mean RT of ES while it tended to increase the RT scores of Is. P did not, however, have an effect on the PI responding of Es and Is. Discussion of these results centered on certain parallels between the performance of introverts and schizophrenic subjects concerning deficits in attention during RT performance.     

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.     

Dopamine modulates frontomedial failure processing of agentic introverts versus extraverts in incentive contexts

The agency facet of extraversion (aE) describes individual differences in goal-directed behavior and has been linked to dopamine function in incentive contexts. Because dopamine presumably modulates the processing of negative feedback/failure, aE may relate to failure processing in incentive contexts. To test this hypothesis, N = 86 participants performed a virtual ball-catching task. An incentive context was created by displaying potential rewards and subtle manipulations of task performance, which either was (control group) or was not (incentive context group) made explicit. To probe the involvement of dopamine, participants received either placebo or the selective dopamine D2 receptor antagonist sulpiride (200 mg). Failure processing was assessed through negative-feedback-evoked differences in the frontal midline theta electroencephalogram power (DFMT) and in the feedback-related negativity event-related potential component (FRN). Before incentives were introduced, DFMT (but not the FRN) was related to neuroticism/anxiety. Importantly, once incentives were displayed, aE was associated with DFMT, FRN, task performance, and changes in self-reported positive affect, which further depended on incentive context group and/or substance group: In the incentive context group but not in the control group, agentic extraverts showed relatively blunted DFMT after placebo. Sulpiride significantly enhanced DFMT, whereas it reduced FRN amplitudes and performance in agentic extra- versus introverts. These findings provide strong support for current dopamine models of aE and failure processing, and also highlight the importance of task context. Moreover, the dissociations of FRN and DFMT suggest the existence of two nonredundant electrophysiological indices of feedback processing, both relating to dopamine and aE.     

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.     

The effect of a low rate of regular signals upon the reaction times of introverts and extraverts

In an RT (reaction time) task involving responding to infrequent, regular signals, extraverts produced higher proportions of missed signals and lengthened RT's than introverts did. This result was only obtained after some time on task and is evidence that inhibitory states are formed more rapidly in extraverted subjects under low stimulation conditions. In a more extended version of the task, mean RT was found to be longer in extraverted than introverted subjects in the second half of the experiment though there was no significant difference between the groups in the first half. These findings are complementary to data from previous studies showing that extraverts generate stronger inhibitory potential in continuous responding tasks, or that their characteristic arousal level may be lower than that of introverted subjects. The need to distinguish between the different explanatory constructs is discussed and a simple model amalgamating the major theoretical positions is outlined.     

Why we are fairer than others

Subjects wrote lists of either fair or unfair things that they or others did. A pervasive tendency was found for subjects to associate themselves with fair behaviors and others with unfair behaviors. When different subjects rated samples of the written behaviors for fairness and frequency we found that fair behaviors were rated as more frequent than unfair behaviors and self-ascribed behaviors were rated as fairer than behaviors ascribed to others. These findings and others are shown to result from a tendency for subjects to perceive a stronger link between the fairness and frequency of their own behavior than between the fairness and frequency of the behavior of other people. A final analysis showed that the subcategories of unfair behavior that subjects associated with others were different from those associated with themselves.     

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.     

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.     

Differences in the transmission of sensory input into motor output between introverts and extraverts: Behavioral and psychophysiological analyses

The present study was designed to investigate extraversion-related individual differences in the speed of transmission of sensory input into motor output. In a sample of 16 introverted and 16 extraverted female volunteers, event-related potentials, lateralized readiness potentials (LRPs), and electromyogram (EMG) were recorded as participants performed a visual choice reaction time task. As additional behavioral indicators of performance, measures of reaction time (RT) and response dynamics were obtained. Although extraversion-related differences were found neither for behavioral measures nor for the N1 and P3 components of the evoked potential, introverts showed a reliably shorter latency in stimulus-locked LRP than extraverts. This latter finding supports the notion of faster stimulus analysis in introverts compared to extraverts. Furthermore, there was no indication of extraversion-related individual differences in speed of response organization and response execution as indicated by response-locked LRP and EMG latencies, respectively. However, a significantly higher EMG amplitude observed with introverts pointed to a less accurately adjusted motor output system of introverts compared to extraverts.     

Music while you work: the differential distraction of background music on the cognitive test performance of introverts and extraverts

The current study looked at the distracting effects of ‘pop music’ on introverts' and extraverts' performance on various cognitive tasks. It was predicted that there would be a main effect for music and an interaction effect with introverts performing less well in the presence of music than extraverts. Ten introverts and ten extraverts were given two tests (a memory test with immediate and delayed recall and a reading comprehension test), which were completed, either while being exposed to pop music, or in silence. The results showed that there was a detrimental effect on immediate recall on the memory test for both groups when music was played, and two of the three interactions were significant. After a 6-minute interval the introverts who had memorized the objects in the presence of the pop music had a significantly lower recall than the extraverts in the same condition and the introverts who had observed them in silence. The introverts who completed a reading comprehension task when music was being played also performed significantly less well than these two groups. These findings have implications for the study habits of introverts when needing to retain or process complex information. © 1997 John Wiley & Sons, Ltd.     

Service job lawyers are happier than money job lawyers,despite their lower income

Giving too much emphasis to extrinsic values and too little emphasis to intrinsic values is known to depress well-being. But is simply working in an extrinsic job also risky, even if that job delivers the money? We compared 1414 ‘Money’ (extrinsic) lawyers, 1145 ‘Service’ (intrinsic) lawyers, and 3415 ‘Other’ lawyers as to their income, values, well-being, and drinking behavior. Although service lawyers had much lower incomes, they also experienced more well-being and less negative affect compared to money lawyers, and drank less and less often. ANCOVAs showed that the intrinsic vs. extrinsic job-type effects were independent of rated intrinsic vs. extrinsic values, current income, years of work experience, and class rank at graduation, suggesting that the job-contexts themselves were operative. We discuss the difficult choice that pre-professional students face, between two versions of the American dream: one emphasizing wealth and status, and the other, service and personal development.     

Hypothesis-testing strategies: Why two goals are better than one

An intriguing finding in the hypothesis-testing literature concerns a large increase in the proportion of subjects who discover a rule when they are asked to determine two rules rather than that rule alone. This finding is based on Wason's (1960) “2 4 6” task, in which subjects try to discover a rule (ascending numbers) by generating and testing number triples. They are initially given an example (“2, 4, 6”) of the rule that leads to overly specific hypotheses. With single-goal (SG) instructions, subjects try to discover the correct rule and are told whether each triple proposed fits the rule. With dual-goal (DG) instructions, correct and incorrect categories are labelled, respectively, as DAX and MED. Subjects try to discover both rules and are told whether each proposed triple is DAX or MED. Two explanations of why DG subjects do better at rule discovery than SG subjects are tested: the quantity of information and the testing of complementary rules using the prevalent positive-test strategy. Results support the latter explanation: DG subjects outperform SG subjects only if they know the rules are complementary, and that SG subjects' performance does not improve when required to test more triples before announcing their first rule. A third explanation, the positivity of the linguistic label of the feedback, is ruled out. Understanding the superiority of DG instructions might suggest a general method for enhancing rule discovery.     

Why Doomsday Arguments are Better than Simulation Arguments

Inspired by anthropic reasoning behind Doomsday arguments, Nick Bostrom's Simulation Argument says: people who think advanced civilisations would run many fully‐conscious simulated minds should also think they're probably simulated minds themselves. However, Bostrom's conclusions can (and should) be resisted, especially by sympathisers with Doomsday or anthropic reasoning. This paper initially offers a posterior‐probabilistic ‘Doomsday lottery’ argument against Bostrom's conclusions. Suggestions are then offered for deriving anti‐simulation conclusions using weaker assumptions. Anti‐simulation arguments herein use more (epistemically and metaphysically) robust reference classes than Bostrom's argument, require no Principles of Indifference, abide better by the total evidence requirement, and yet use empirically plausible priors and likelihoods. However, while Doomsday arguments are probabilistically, epistemically and metaphysically stronger than the Simulation Argument, anthropic reasoning can (and should) refrain from embracing either.