Transfer tests of an extinction cue in appetitive conditioning with rats

Two Pavlovian appetitive conditioning experiments with rats assessed extinction cue (EC) transfer using spontaneous recovery tests. In each experiment, after conditioned stimulus (CS) A-US pairings, an EC (X) was presented during A-extinction, followed by spontaneous recovery testing with A. Experiment 1 tested for transfer between ECs; the additional CS (B) was conditioned and then was extinguished with a second EC (Y). CS A was tested with X and with Y (the possible transfer EC). Experiment 2 tested for transfer between an EC and an explicitly trained serial negative occasion setter (OS). Prior to testing with A, Y was trained in a serial Y→C-, C + discrimination; a Z→B-, B + discrimination was also trained. A was tested with X and with Y (with Y as the possible transfer OS). X and Y were also tested with B (where X with B tests possible EC-OS transfer). In each experiment Y did not reduce spontaneous recovery to A, showing no transfer of one EC to another (Experiment 1) and no transfer of a serial negative OS to a CS (A) extinguished with an EC (X; Experiment 2). X did not reduce responding to B, showing no transfer of an EC to the target CS of a serial negative OS discrimination, although Y did transfer to B (Experiment 2) showing transfer between serial OSs. X did reduce responding to the CS (A) it had occurred with during extinction (Experiments 1 and 2). The results are discussed in terms of EC characteristics and regarding theories of an EC's possible mechanisms.