An analysis of reinstatement after extinction of a conditioned taste aversion

Abstract

Taste aversion learning has sometimes been considered a specialized form of learning. In several other conditioning preparations, after a conditioned stimulus (CS) is conditioned and extinguished, reexposure to the unconditioned stimulus (US) by itself can reinstate the extinguished conditioned response. Reinstatement has been widely studied in fear and appetitive Pavlovian conditioning, as well as operant conditioning, but its status in taste aversion learning is more controversial. Six taste-aversion experiments with rats therefore sought to discover conditions that might encourage it there. The results often yielded little to no evidence of reinstatement, and we also found no evidence of concurrent recovery, a related phenomenon in which responding to a CS that has been conditioned and extinguished is restored if a second CS is separately conditioned. However, a key result was that reinstatement occurred when the conditioning procedure involved multiple closely spaced conditioning trials that could have allowed the animal to learn that a US presentation signaled or set the occasion for another trial with a US. Such a mechanism is precluded in many taste aversion experiments because they often use very few conditioning trials. Overall, the results suggest that taste aversion learning is experimentally unique, though not necessarily biologically or evolutionarily unique. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Figure 1.

Mean saccharin consumption (ml) during acquisition, extinction, and reinstatement tests of Experiment 1. Error bars represent the standard errors of the means.

Figure 2.

Mean consumption data (ml) on critical trials of Experiment 2. Error bars represent standard errors of the means.

Figure 3.

Mean consumption (ml) for acquisition, extinction, and reinstatement tests of Experiment 3. Error bars represent standard errors of the means.

Figure 4.

Mean consumption (ml) of saccharin during acquisition. Error bars represent standard errors of the means.

Figure 5.

Percent sick behavior in rats after receiving LiCl injections during acquisition, in five-minute intervals during acquisition trials 2, 5, and 8.

Figure 6.

Consumption of saccharin for individual subjects during Extinction in Experiment 4.

Figure 7.

Mean consumption data (ml) on critical trials of Experiment 4. Reinstatement tests are shown at right. Error bars represent standard errors of the means. C1 = first conditioning trial, E1 = first extinction trial, E(L-1) = second-to-last extinction trial, E(L) = last extinction trial, T1 and T2 = tests 1 and 2.

Figure 8.

Mean consumption (ml) of sucrose and citric acid during acquisition. Error bars represent standard errors of the means, but are difficult to detect because variability was low.

Figure 9.

Consumption during extinction trials for individual subjects in Experiment 5.

Figure 10.

Mean consumption data (ml) on critical trials of Experiment 5. Reinstatement tests are shown at right. Error bars represent standard errors of the means. C1 = first conditioning trial, E1 = first extinction trial, E(L-1) = second-to-last extinction trial, E(L) = last extinction trial, T1 and T2 = tests 1 and 2.

Figure 11.

Mean flavor consumption (ml) during acquisition in Experiment 6. Error bars represent standard errors of the means, but are difficult to detect because of low variability.

Figure 12.

Consumption during extinction trials for individual subjects in Experiment 6.

Figure 13.

Mean flavor consumption (ml) on critical trials of Experiment 6. Reinstatement tests are shown at right. Error bars represent standard errors of the means. C1 = first conditioning trial, E1 = first extinction trial, E(L-1) = second-to-last extinction trial, E(L) = last extinction trial, T1 and T2 = tests 1 and 2.