Parsing attentional components during a simple reaction time task using sleep deprivation and amphetamine intervention.

To examine the independent contributions of the attentional components of arousal and activation in performance, sleep deprivation was used as the attentional manipulation in a reaction time (RT) task. The subjects were 18 men who underwent 63 hr. of sleep deprivation during which time they periodically performed a simple auditory RT task with manipulations of temporal uncertainty and intensity. After 48 hr. sleep deprivation, subjects ingested either 20 mg d-amphetamine or placebo, then continued testing throughout Day 3. During sleep deprivation, performance was more impaired on trials associated with low temporal uncertainty (arousal) and high preparation (activation) than on trials associated with high temporal uncertainty and low preparation. Analysis indicated that sleep deprivation perturbed activation, leaving arousal relatively unimpaired and that amphetamine had a restorative effect on the sleep deprivation-impaired activation system. The stimulus of high intensity was disruptive on Day 1 but facilitative on Day 3, a result which was interpreted as an initial inhibition, then disinhibition of arousal. Results were interpreted to indicate that, in some instances, alterations in the less specific arousal and activation systems may underlie impairment or changes in the more specific information processing and motor output stages.