Perceived Time Progression and Vigilance: Implications for Workload, Stress, and Cerebral Hemodynamics

Abstract : This study tested the possibility that the temporal context in which a vigilance task is performed will moderate the perceived workload and stress of the task. We employed a procedure to manipulate participants' perceived time progression (PTP) during task performance by creating a mismatch between their expectations about how long they would perform the task and the actual time they were engaged (Sackett et al., 2010). All participants completed two 30-minute vigilance task sessions, separated by a 15-minute rest period. Those in a time drags condition were led to believe each session would last 15 minutes while those in a time flies condition were told each would last 60 minutes. A control group was informed of the true length of the vigil with no attempt to manipulate PTP. PTP was significantly slower in the time drags and control conditions compared to the time flies condition. However, measures of performance (perceptual sensitivity and response bias), workload scores on the NASA Task Load Index, stress scores on the Dundee Stress State Questionnaire, and cerebral hemovelocity scores were similar in all conditions. Evidently, vigilance tasks are perceived as hard work even when time flies.