Stimulus–outcome associations are required for the expression of specific Pavlovian-instrumental transfer

January 2024

Abstract

A series of experiments employed a specific Pavlovian-instrumental transfer (PIT) task in rats to determine the capacity of various treatments to undermine two outcome-specific stimulus–outcome (S–O) associations. Experiment 1 tested a random treatment, which involved uncorrelated presentations of the two stimuli and their predicted outcomes. This treatment disrupted the capacity of the outcome-specific S–O associations to drive specific PIT. Experiment 2 used a negative-contingency treatment during which the predicted outcomes were exclusively delivered in the absence of their associated stimulus. This treatment spared specific PIT, suggesting that it left the outcome-specific S–O associations relatively intact. The same outcome was obtained in Experiment 3, which implemented a zero-contingency treatment consisting of delivering the predicted outcomes in the presence and absence of their associated stimulus. Experiment 4 tested a mixed treatment, which distributed the predicted outcomes at an equal rate during each stimulus. This treatment disrupted the capacity of the outcome-specific S–O associations to drive specific PIT. We suggest that the mixed treatment disrupted specific PIT by generating new and competing outcome-specific S–O associations. By contrast, we propose that the random treatment disrupted specific PIT by undermining the original outcome-specific S–O associations, indicating that these associations must be retrieved to express specific PIT. We discuss how these findings inform our theoretical understanding of the mechanisms underlying this phenomenon.