Online

Michaud, Noëlle Lorèn

Psychology

2023

Ph. D.

Taste aversion learning has sometimes been considered a special form of learning. The unique way in which the taste of a poisonous food and its gastrointestinal consequences may typically occur in nature might encourage the evolution of a unique and biologically adaptive learning system. Six experiments were designed to address whether reinstatement, a well-known effect that occurs after extinction, can be observed in taste aversion learning. After a conditioned stimulus (CS) is conditioned and extinguished, reexposure to the unconditioned stimulus (US) by itself sometimes reinstates the conditioned response (CR). Reinstatement has been widely studied in fear and appetitive conditioning preparations, but its status in taste aversion learning is less clear. The first two experiments replicated the methods (with minor modification) of an experiment done by Schachtman, Brown, and Miller (1985), which found significant reinstatement in taste aversion learning but conflicted with results of similar studies that had been reported by Bouton (1982), which did not find reinstatement of taste aversion. The third experiment investigated the possibility of concurrent recovery (the return of the CR to one CS after extinction of it and conditioning of a different CS) in taste aversion learning, given that the effect seems to occur in at least one other setting (rabbit nictitating membrane response conditioning) where reinstatement does not. The last three experiments developed new taste aversion methods that might enhance the ability to produce a reinstatement effect in taste aversion learning based on what we know about the variables that allow for reinstatement and/or reacquisition in other settings (specifically when we manipulate trials and USs to readily signal more upcoming trials and USs).In Experiment 1, replication of the Schachtman et al. (1985) methods using the home cage throughout the experiment failed to create a reinstatement effect. In Experiment 2, using a novel reinstatement context produced a very small reinstatement effect, but this result goes against existing literature suggesting that the reinstatement and test phases must both occur in the same context. Using the Experiment 1 method, which does not produce a reinstatement effect, I tested for, and did not find evidence of, a concurrent recovery effect. Despite increasing the potential influence of trial/US signaling by increasing the number of conditioning trials as well as shortening the reinstatement-to-test interval, the results of Experiments 4 and 5 also did not suggest evidence of reinstatement. However, in Experiment 6, when there were two conditioning trials per day (as opposed to one), and when the reinstatement-to-test interval matched the 5-hr interval between the daily conditioning trials, there was evidence of a reinstatement effect. The results support contextual conditioning theories of learning and suggest that trial/US signaling must be maximized in order to observe reinstatement of an extinguished taste aversion.