Effects of an Attention-Demanding Task on Amplitude and Habituation of the Electrodermal Orienting Response

Two experiments were designed to investigate the effects of performance of a central task on habituation of the skin conductance response to task-irrelevant stimuli. In Experiment 1 (N=48), subjects performed a visual monitoring task in which stimuli were presented at either 800 or 1000 msec. Half the subjects in each group received task-irrelevant tones of 70dB while the other half did not. The results indicated that task-irrelevant tones elicited responses that were larger than those associated with performance of the monitoring task itself, and that responses were larger and habituation slower in the high demand (800 msec) condition than in the low (1000 msec). In order to distinguish between different explanations of these results, Experiment 2 (N=64) employed the same central task and utilized an unexpected change in the pitch of the task-irrelevant stimulus after 20 habituation trials. The results indicated that although habituation was again slower in the high demand condition than in the low, change trial responsiveness was less in the former than in the latter. The results are discussed in terms of arousal and information-processing accounts of habituation.