Individual differences in energetic arousal and sustained attention: a dual-task study

Studies of sustained attention and controlled visual search suggest that individual differences in energetic arousal are correlated with availability of resources for demanding attentional tasks. However, most of the evidence for this resource hypothesis is derived from studies of single tasks, in which it is difficult to distinguish effects of energy on resource availability from effects on the subject's strategy for allocation of resources across task components. We report a dual-task study of energy and sustained attention, which provides a more powerful test of the hypothesis. High and low energy individuals performed a primary visual vigilance task, in conjunction with either an auditory (n = 52) or a visual (n = 50) secondary reaction-time task. Primary task stimuli were presented at two levels of stimulus degradation, as a manipulation of resource limitation. No effects of energy were observed when the secondary task was auditory, but the primary task performance of high energy individuals was superior when the secondary task was visual and primary task stimulus discriminability was low. Results are consistent with previous work on energy and single-task performance suggesting that energetic arousal is associated with individual differences in resource availability, but they also illustrate the importance of careful control of task parameters. (C) 2001 Elsevier Science Ltd. All rights reserved.