Effect of extinction duration on outcome-selective reinstatement of instrumental responses.

Abstract

Two-experiments were designed to analyze outcome-selective instrumental reinstatement (Experiment 1) and the effect of extinction on this sort of reinstatement (Experiment 2). In Experiment 1 two groups of rats were trained in three phases. In the first phase two-daily sessions were conducted. For the Different Group Response (R) 1 was reinforced with the (O) Outcome 1 in one of these sessions, and in the other session R2 was reinforced with the O2, while for the Same Group both responses were reinforced with the same outcome. In the extinction phase, outcomes were discontinued while both responses were available. Finally, in the test phase groups were re-exposed to one of the outcomes used in the first phase. In Experiment 2 a similar procedure to that described for Experiment 1 was used, three groups of rats (i.e. Same, Different O1 and Different O2) were trained in four sequential phases: Acquisition of R1, Acquisition of R2, Extinction and Test. In the test phase all groups were exposed to one of the outcomes used in either Acquisition phases, after 5 or 10 extinction sessions. Findings showed selective outcome reinstatement in both experiments, although Experiment 2 showed selective reinstatement only after 5 extinction sessions, but not after 10 extinction sessions. Results are discussed in terms of the properties of discriminative stimulus of the reinstatement outcome.