The role of reinforcement in controlling sequential IRT dependencies

Sequential dependencies were investigated with two rats in a mixed and in a tandem differential-reinforcement-of-low-rate-responding schedule. In each schedule, 5-sec and 15-sec components were presented in fixed alternation. In the mixed schedule, a 5-sec interresponse time followed a 15-sec interresponse time and a 15-sec interresponse time followed a 5-sec interresponse time in predictable sequence. The correlation between prior and subsequent interresponse times, however, existed only when the prior interresponse time resulted in reinforcement. In the tandem schedule, an interresponse time greater than 5 sec in the differential-reinforcement-of-low-rate 5-sec component was not associated directly with reinforcement. One subject demonstrated sequential response patterns similar to those noted in the mixed schedule, even though the prior 5-sec interresponse time was not reinforced in the tandem schedule. The results indicate that the prior interresponse time length alone is not sufficient to influence the subsequent interresponse time length. Implications are, however, that a temporal response pattern arises when an interresponse interacts with schedule contingencies to control the interreinforcement interval.