“Aware” (A) and “naive” (N) groups received different instructional sets, the former being informed both of the nature of their task and the response-reinforcement contingency. Negative reinforcement was given to these groups whenever a spontaneous GSR was emitted during four 4-min trial periods. Two corresponding yoked-control groups, CA and CN, received non-contingent reinforcement over the same periods. The contingent reinforcement groups both showed learned suppression of spontaneous GSR activity, but comparison between the A and N groups revealed a significant interaction between Time and Instructional Set. It is suggested that the “aware” instructional set had an inhibitory effect upon learning.