Delayed habituation of the electrodermal orienting response as a function of increased level of arousal.

Level of arousal was manipulated by having subjects perform arithmetic tasks during a habituation procedure, which consisted of 55 presentations or a 1000 Hz. 80 dB tone. For one group a threat of shock was added to the task performance in order to include aspects of stress in the arousal manipulation. These two groups were compared with a group who heard the same stimuli but were simply instructed to relax. The three groups differed in level of arousal according to KEG signs of drowsiness, skin conductance level, and frequency of spontaneous skin conductance responses, All three groups differed from each other in number of trials to habituation criterion for skin conductance responses to stimuli. Since the delay of habituation was seen tin- both the Task group and the Shock-threat group, it was concluded that the effect was not bound to aspects of stress but was a general effect of increased arousal. For vasomotor responses an analysis in terms of habituation was difficult to apply because the two high arousal groups were very unresponsive from the beginning.