Priming and trial spacing in extinction: Effects on extinction performance, spontaneous recovery, and reinstatement in appetitive conditioning

Abstract

Previous research in this laboratory suggests that priming of the conditional stimulus (CS) in short-term memory may play a role in the trial-spacing effects in appetitive conditioning. For example, a nonreinforced presentation of a CS 60 s before a reinforced trial with the same CS produced slower acquisition than a CS presentation that occurred 240 s before the reinforced trial. The results were consistent with the self-generated priming mechanism proposed by Wagner (e.g., Wagner 1978, 1981). The present experiments extended the earlier work by examining the effects of trial spacing in extinction rather than acquisition. After conditioning with a mixture of intertrial intervals (ITIs), rats received extinction with ITIs of 60 or 240 s, longer or shorter values, or different ways of “chunking” extinction trials in time. Although trial spacing produced effects on extinction performance that were consistent with our previous research on acquisition, there were few long-term differences in spontaneous recovery or in reinstatement. Short ITIs in extinction appear to affect extinction performance more than they affect extinction learning. Mechanisms of trial spacing in conditioning and extinction are discussed.

Acknowledgments

This research was supported by Grant RO1 MH64847 from the National Institute of Mental Health to MEB. We thank Alexandra Modzelewska for her early work on the project, and Ana Garcia-Gutierrez and Amanda Woods for their comments on the manuscript.

Notes

¹ Sunsay et al. (2004) also identified a short-term priming effect that was caused by reinforced as opposed to nonreinforced primes. With reinforced primes, priming is mainly caused by presentation of the US. Once again, the effect is over within 240 s and is at least partly due to a performance-suppressing process.