The acquisition and maintenance of lever pressing by rats with conditioned

Abstract

Rats were used to study the effect of two parameters of a procedure previously used to investigate conditioned reinforcement with pigeons. One of these parameters is the frequency of response-independent pairings of a 1s signal with food. Variable inter-pairing signal-food intervals with means of either 60,120 or 240s were guessed to be appropriate for rats. The other parameter is the frequency with which lever pressing produced the 1s signal. Variable inter-signal intervals with means of either 7.5, 15 or 30s were also guessed to be adequate for rats. These parameter values were combined according to a factorial design for three rats per cell during the acquisition and further maintenance of responding. Rates of responding decreased when the signal-food inter-pairing interval and the inter-signal interval were lengthened. While the former effect differed from that reported for pigeons, the latter agrees with previous research. It was concluded that the present procedure avoids some problems of other methods to study conditioned reinforcement and that for practical reasons, by allowing the acquisition and maintenance of responding by rats, may facilitate further research on the establishment of responding under degraded conditions of conditioned reinforcement.