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

Abstract

SUMMARYThe personality dimension of introversion/extraversion is one of the few personality dimensions that can be reliably identified from study to study and investĝ ator to investigator. The importance of this dimension 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 processed is responsible for these performance changes. One of the few personality dimensions that most personality theorists agree is robust enough to identify from study to study and investigator to investigator is that of introversion/extraversion. It has been shown that this personality dimension can be identified in such varied item sets as behavioral measures ...

Personality and conditioning: A test of four models.

“…The personality questionnaires administered included the following: (a) the Eysenck Personality Inventory (EPI; H. J. Eysenck & Eysenck, 1975a), which includes 241/E items, 24 S/N items, and 9 lie items (within the I/E scale there are subscales for Imp and sociability, see Revelle et al, 1980); and (b) the A-Trait scale from the State-Trait Anxiety Inventory (STAI; Spielberger, Gorsuch, & Lushene, 1970). In addition, there were several other personality questionnaires given in Experiment 1; the results from these additional questionnaires are not discussed in this article.…”

“…In view of the evidence that individual differences in diurnal arousal patterns are related to Imp (e.g., Revelle, Humphreys, Simon, & Gilliland, 1980), we varied time of day systematically across the four experiments in order to test the robustness of the relation of personality and conditioning with respect to diurnal arousal patterns. A second variable that was systematically varied across the four experiments was the strength of a dominant response set induction.…”

Impulsivity and time of day: Is rate of change in arousal a function of impulsivity?

“…Individual differences were assessed with the Eysenck Personality Inventory (EPI; H. J. Eysenck & Eysenck, 1964), using the impulsivity subscale identified by Revelle et al (1980). Scores on this scale, which emphasizes spontaneity and rapidity of cognitive and behavioral activity, have repeatedly been shown to mediate performance as expected on the basis of predictions from arousal theory (e.g., Anderson, in press;Anderson & Revelle, 1982;Bowyer et al, 1983;Revelle et al, 1980).…”

“…Moreover, research suggests that the personality-arousal relationship is mediated by phase differences in diurnal arousal rhythms (e.g., Blake, 1967;Revelle et al, 1980). In general, arousal increases during the morning, levels off or decreases slightly through the afternoon, and then declines during the evening; extraverts lag behind introverts in this pattern.…”

“…First, there is mounting evidence that it is impulsivity, rather than sociability or extraversion, that is arousal related (e.g., Anderson, in press;Bowyer, Humphreys, & Revelle, 1983;Campbell, 1992; H. J. Eysenck & Levey, 1972;Frcka & Martin, 1987;Loo, 1980;O'Gorman & Lloyd, 1987;Revelle, Humphreys, Simon, & Gilliland, 1980;Schalling et al, 1983;Stenberg, 1992).…”