Counter conditioning in an operant conflict situation.

Abstract
Food and shock were both programed for 8 rats on identical 1 -min. variable-interval schedules. The effectiveness of shock in reducing lever-pressing rate was reduced when food and shock were always presented together, rather than always separately. This finding demonstrated counter conditioning of the aversive effects of shock in a free-operant situation and showed that the temporal relationship between reward and punishment may be an important determinant of conflict performance.