Visual signal detection as a function of sequential variability of simultaneous speech.

Abstract

Two experiments compare signal detection (brightness discrimination) during 2 concurrent cognitive tasks, varied talking and repetitive counting. 24 Ss served 2 2-hr, sessions under each talking conditioa Reported drowsiness (p <. 001) and sleeping were higher during counting sessions and detections correlated between [long dash]. 39 and [long dash]. 64 with drowsiness. However, detections were not different under the 2 conditions. In Experiment II, 40 Ss served 8 3-min. trials under each condition with counterbalancing to minimize differential arousal. Lively band music between trials maintained arousal. Detections were significantly lower under varied talking (p <. 001). Results suggest that when environmental stimulation maintains arousal, S-generated cognitive stimuli interfere with signal detection; when environmental stimulation is low, S-generated stimuli support arousal but the positive effect of arousal on detections is obscured by the interference effect of S-generated cognitive stimuli.