Electrodermal discrimination with visual feedback in two incompatible stressful situations. A yoked control comparison.

One group (N = 14) of human volunteers received three sessions of discriminated avoidance and punishment with the skin resistance response (SRR) as the instrumental behavior. Each session consisted of three 7 minute periods of Sidman avoidance (response-stimulus [R-S] and stimulus-stimulus [S-S] = 40 sec) of a 0.5 second, 15 Hz square wave shock mixed with three periods of punishment with the same shock. The avoidance and punishment periods were differentially signaled by red and green lights, and a circle appeared superimposed on the discriminative stimuli during a criterion SRR. A second group (N = 14) was yoked to the first by recording shock events on magnetic tape and shocking the yoked subject in the same temporal sequence. In both groups the visual feedback stimulus was consistently related to the subject's ongoing electrodermal behavior. As in previous research, the contingent shock subjects made significantly more SRRs during avoidance than during punishment in all three sessions. For yoked subjects the discrimination did not appear until the third session. The findings imply that the discrimination is at least partly independent of the avoidance and punishment contingencies, and they raise questions about the role of the feedback stimulus.