Attentuation of the Vigilance Decrement through Stimulation in a Second Modality

Abstract

The use of discrete, randomly-placed tones to attenuate a decrement in performance in a visual vigilance task was studied. As the measure of vigilance, the descending CFF threshold was taken at 15 time intervals throughout the hour watch. 60 male subjects were assigned to one of the six conditions of the experiment. A regular or irregular pattern of intervals for the presentation of the visual stimuli was combined with one of three sound conditions: (1) a ready signal in the form of a 1000 cps tone lasting one second and indicating the start of a visual signal, (2) tones of the same dimensions randomly placed and not indicating the presence of a visual signal, (3) no tones. The results indicated optimum performance for condition (1) with conditions (2) and (3) following in that order and confirming that the vigilance decrement can be attenuated to a significant degree when random auditory stimulation is provided. No significant difference was found between the two types of visual patterns.