A study of two factors which affect arousal level and the apparent duration of a ten-minute interval.

Abstract

Interview studies of aircrew suggested that the apparent duration of an interval during flight might be affected both by the demand made on the individual by his allotted task and by the amount of background distraction to which he was exposed. In a laboratory experiment, eight pilots were isolated for four intervals of 10 min. During two of the intervals the pilots were required to perform a simple tracking task, whilst in the other two they were not required to do anything; on one occasion for each task condition they were exposed to distracting stimulation. The palmar skin resistance was measured every 1/2 min. during each 10 min. interval; afterwards the subject estimated its duration and indicated how alert he had been during it. The apparent duration was increased by the presence of distraction and decreased by the performance of the task; however, the effects of distraction and performance of the task on alertness and skin conductance were similar, both being in the direction of an increase in arousal. It was found that arousal changes could not account for more than an insignificant proportion of the observed alterations in apparent duration. It is concluded that an explanation in terms of the way in which attention is organized under the particular conditions of isolation obtaining is both consistent with the findings and may be a fruitful line for future investigation.