Habituation of the electrodermal orienting reaction is dependent on the cerebral hemisphere initially stimulated

The purpose of the present study was to investigate the relationship between habituation of the electrodermal orienting reaction (OR) and asymmetrical hemisphere functioning. Subjects were exposed to lateralized visual input with fear-relevant and neutral content. Skin conductance recordings were taken bilaterally. The experiment consisted of four groups in a randomized 2 X 2 factorial design (N = 40). Half of the subjects habituated to repeated presentations (25 trials) of a snake-slide, whereas the other half viewed a slide of a rectangular black geometric shape. Within each stimulus category, half of the subjects had the picture presented 6 degrees of visual angle lateral to the right of a central fixation point (i.e. initial right hemisphere input). The other half had the picture presented to the left (i.e. initial right hemisphere input). Results showed a significant overall decrease in response magnitude over trials, and a significant main effect of type of projection field. Responses in the left field groups were larger than responses in the right field groups on all trials. No other comparisons reached significance. The results are discussed in terms of hemisphere asymmetry and its role in the regulation of the habituation process.