Eye Movements during Vigilance

Abstract

This study concerns eye movements recorded during a vigilance situation. Evidence was obtained on where people looked when they were watching for signals, which were 0.5-sec. pauses in the motion of a slowly revolving pointer. The following results were obtained: (1) Detection probability for two dials was approximately half the detection rate for one dial. (2) Analysis of eye-movement records showed that in the one-dial situation every missed signal was fixated without being recognized. (3) In the two-dial condition, signals were not only either fixated or unfixated, but some were fixated for part of their duration. Approximately one-third of the signals fell into each fixation category. (4) In contrast to the one-dial condition, the largest proportion of unreported signals for two dials were not fixated at all. Nearly as many unreported signals were partially fixated. About one-quarter of the unreported signals were fixated for their full duration. (5) Individual Ss differed with respect to the time they paused on one dial before shifting to the other. Those who shifted more frequently detected more signals.