The use of bilateral skin conductance measurement in elucidating stimulus versus response processing influences on the orienting reaction

In three experiments the importance of behavioural consequences as a determinant of the amplitude of the electrodermal response is demonstrated. Bilateral skin conductance responses were examined to same-different stimuli consisting of moderate intensity tones differing in pitch (S1, S2), to a response cue to make a unimanual button-press if the stimulation were judged the same (S3), and to feedback (S4). In the first two experiments in which a right-hand action was required, responses were larger to S2 than S1 on ‘response’, compared with ‘no-response’ trials. This was replicated in the second experiment where the same effect was also found to S3. In the third experiment the hand performing the action was varied; the influence of stimulus consequences on responses to S2 was replicated when the right hand performed the action; when the left hand was involved elevated responses to S2 occurred, irrespective of the perceptual judgement. In all experiments responses tended to be larger on trials where a correct judgement was made. The use of bilateral recording with a unilateral behavioural response confirmed the influence of effector functions on electrodermal responses. Hemispheric influences were contralateral and excitatory. The results were discussed in terms of multiple central determinants on electrodermal responses, the influence of cerebral laterality, and of sympathetic-somatic coupling.