Pavlovian-to-Instrumental Transfer: Paradoxical Effects of the Pavlovian Relationship Explained

Pavlovian-to-instrumental transfer (PIT) is a key concept in developing our understanding of cue-controlled behaviours. Here we have reviewed the literature on behavioural and neurobiological factors that influence PIT. Meta-analyses of the data for individual groups in PIT studies revealed that PIT is related to both the order and amounts of instrumental and Pavlovian training, and that it is critically determined by competition between instrumental and Pavlovian responses. We directly addressed the role of response competition in PIT in two experiments which showed that extensive Pavlovian conditioning produced more Pavlovian magazine visits and weaker PIT than moderate Pavlovian conditioning (Experiment 1); and that PIT lost after extensive Pavlovian conditioning was restored by Pavlovian extinction training (Experiment 2). These findings confirm that response competition is indeed an important determinant of PIT. This has significant implications for lesion and inactivation studies that assess the neurobiological substrates of PIT, as well as attempts to demonstrate PIT in the drug self-administration paradigm where the effect is yet to be reliably shown.