Sign-tracking is an expectancy-mediated behavior that relies on prediction error mechanisms

  1. Andrew R. Delamater4
  1. 1Department of Neuroscience Graduate Program, University of Michigan, Ann Arbor, Michigan, 48109, USA
  2. 2Neuroscience and Cognitive Science, University of Maryland, Maryland, 20742, USA
  3. 3Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, New York 11794, USA
  4. 4Department of Psychology, Brooklyn College and Graduate Center of the City University of New York, Brooklyn, New York 11210, USA
  1. Corresponding author: rderman{at}umich.edu

Abstract

When discrete localizable stimuli are used during appetitive Pavlovian conditioning, “sign-tracking” and “goal-tracking” responses emerge. Sign-tracking is observed when conditioned responding is directed toward the CS, whereas goal-tracking manifests as responding directed to the site of expected reward delivery. These behaviors seem to rely on distinct, though overlapping neural circuitries, and, possibly, distinct psychological processes as well, and are thought to be related to addiction vulnerability. One currently popular view is that sign-tracking reflects an incentive motivational process, whereas goal-tracking reflects the influence of more top-down cognitive processes. To test these ideas, we used illness-induced outcome-devaluation and Kamin blocking procedures to determine whether these behaviors rely on similar or distinct underlying associative mechanisms. In Experiments 1 and 2 we showed that outcome-devaluation reduced sign-tracking responses, demonstrating that sign-tracking is controlled by reward expectancies. We also observed that post-CS goal-tracking in these animals is also devaluation sensitive. To test whether these two types of behaviors rely on similar or different prediction error mechanisms, we next tested whether Kamin blocking effects could be observed across these two classes of behaviors. In Experiment 3 we asked if sign-tracking to a lever CS could block the development of goal-tracking to a tone CS; whereas in Experiment 4, we examined whether goal-tracking to a tone CS could block sign-tracking to a lever CS. In both experiments blocking effects were observed suggesting that both sign- and goal-tracking emerge via a common prediction error mechanism. Collectively, the studies reported here suggest that the psychological mechanisms mediating sign- and goal-tracking are more similar than is commonly acknowledged.

  • Received January 31, 2018.
  • Accepted June 29, 2018.

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