Performance on a Simple Vigilance Task in Noise and Quiet

Twenty subjects, working individually, monitored a simple vigilance task, a modified “Mackworth Clock Test,” for 134 hr in noise (112.5 db SPL) and for 134 hr in quiet (79 db SPL). No difference in efficiency attributable to noise level was found. This result is in conflict with previous reports from this and other laboratories which ascribed decrement in performance on vigilance tasks to noise levels. Vigilance tasks in which performance decrements due to noise were found, differed from the present task in that they required subjects to scan a series of displays in addition to maintaining vigil over each display. It is, therefore, suggested that flexibility of attention may be affected by noise, whereas vigilance without the requirement for flexibility may be unaffected.