Renewal in a heterogeneous behavior chain: Extinction of the first response prevents renewal of a second response when it is separately extinguished and returned to the chain

Abstract

Two experiments with rat subjects examined the renewal of an extinguished instrumental response that occurs when it is returned to the context of a behavior chain in which it had been trained. In both experiments, rats first learned a discriminated heterogeneous chain in which a stimulus (S1) set the occasion for one response (R1), the emission of which turned off S1 and turned on a second stimulus (S2) that set the occasion for a second response (R2). R2 in turn terminated S2 and earned a food-pellet reinforcer. When R2 was extinguished separate from the chain, it was renewed when it was returned to and tested in the chain. However, in both experiments, separate extinction of R1 prevented this renewal of R2 from occurring. In Experiment 2, Pavlovian extinction of S1 without the opportunity to emit R1 during extinction also weakened the renewal of R2 and had an unexpected effect of weakening R1. The results are consistent with the idea that R1 can be an important part of the “context” controlling R2 in a discriminated chain. They also suggest that Pavlovian extinction of a discriminative stimulus can weaken the instrumental response under some conditions.