Effects of Stimulus Variability on the Amplitude and Habituation of the Electrodermal Orienting Response

ABSTRACT Two experiments using 12 male subjects were conducted to study the effects of stimulus information on the amplitude and habituation of the electrodermal orienting response (OR). Visual stimuli which could be varied along information, contour, and symmetry dimensions were presented. In the first experiment, 2 series of 10 different stimuli each were presented; 1 series was characterized by high information and high contour, the other by low information and low contour. No difference in OR habituation between the 2 series was found. In the second experiment, the 2 series of stimuli were again presented with 3 test stimuli inserted at Trials 3, 6 and 9. Test stimuli differed from habituation stimuli by symmetry or information and/or contour. Changes in stimulus information or contour, but not symmetry, resulted in OR recovery. OR recovery did not result in dishabituation of the following stimuli. Results are interpreted as favoring an information processing model of OR habituation. Findings suggest that laws governing habituation processes under conditions of identical stimulus presentations may differ from those operating when stimuli are variable.