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J Pers Soc Psychol. 1994 Aug;67(2):334-44.

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

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Department of Psychology, Northwestern University, Evanston, Illinois 60208.


Impulsivity has been interpreted as a stable mediator of rate of change in arousal states. To test this hypothesis, 129 Ss differing in impulsivity were given placebo or caffeine at 9:00 a.m. or 7:30 p.m. Recognition memory was tested for the last 20 items from 2 lists of 24 items and 2 lists of 80 items. Scores from this paradigm reflect sustained attention and are thus sensitive to changes in arousal. A 4-way interaction among impulsivity, time of day, drug, and prior stimuli (p < .05) indicated that for those given placebo, recognition memory for long and late lists was poorer the higher the impulsivity in the morning; this pattern reversed in the evening. Caffeine reduced recognition errors. These results indicate that impulsivity is not a stable predictor of rate of change in arousal states. Instead, susceptibility to attentional lapses is mediated by impulsivity-related phase differences in diurnal arousal rhythms.

[Indexed for MEDLINE]

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