POSITIVE CONDITIONED SUPPRESSION: AN EXPLANATION IN TERMS OF MULTIPLE AND CONCURRENT SCHEDULES 1

Rats performed under a baseline variable‐interval schedule of food presentation. A response‐independent food schedule was then superimposed on the baseline schedule for different periods of time across different conditions. The response‐independent schedule operated for the whole session in some conditions, intermittently for sixty second periods in some, and intermittently for ten‐second periods in others. Under these latter two sets of conditions, the response‐independent food schedule was stimulus correlated and alternated with the baseline schedule according to a multiple schedule. Response‐independent food presentations always suppressed responding. The degree of suppression tended to increase the longer the period of response‐independent food. Control conditions, in which the superimposed schedule was response‐dependent, rather than response‐independent, did not produce response suppression. The results fit an analysis of positive conditioned suppression phenomena in the context of multiple and concurrent schedule effects.