THE DIFFERENTIAL CONDITIONABILITY OF TWO COMPONENTS OF THE SKIN CONDUCTANCE RESPONSE

The dual effector basis of the skin conductance response (SCR) was investigated in an experiment in which responses from both the dorsal and palmar surfaces of the hand were classically conditioned using a delayed, discrimination conditioning paradigm. Orienting (OR), anticipatory (AR) and unconditional responses (UCR) were distinguished on the basis of latency. Both the anticipatory response and the response which occurred when the unconditional stimulus (UCS) was omitted (CR) were conditional. The magnitude of the response from the dorsal and palmar placements was similar for the ORs, UCRs, and CRs, but the palmar ARs were significantly greater than the dorsal. A conditioning index which took into account the magnitude of the UCR, revealed that the palmar AR differentiated between reinforced and non-reinforced conditional stimuli to a greater degree than the dorsal response. These results are consistent with the hypothesis that the epidermal component of the SCR, reflected in measurements from the dorsum of the hand, accompanies the alerting or orienting response of the organism, whereas the sweat gland component of the SCR, represented largely in measurements from palmar sites, is primarily associated with a defensive, anxiety-like response.