Development of Pavlovian-to-instrumental transfer (PIT) task to examine the effects of reward-predicting cues on behavioral activation in young adults

There is a growing recognition that much of human behavior is governed by the presence of classically conditioned cues. The Pavlovian-to-Instrumental Transfer (PIT) paradigm offers a way to measure the effects of classically conditioned stimuli on behavior. In the current study, a novel PIT paradigm was developed for use in conjunction with an fMRI classical conditioning task. This could allow for a measurement of BOLD responses to anticipated rewards, unconfounded by operant responses, while providing a behavioral measure of conditioning effects. Twenty-four healthy young adults completed 1) instrumental training, 2) Pavlovian conditioning, and 3) Transfer test. During instrumental training, participants learned to apply force on a handgrip to win money from slot machines pictured on a computer screen. During Pavlovian conditioning, slot machines appeared with one of two abstract symbols (cues), one symbol was predictive of monetary reward. During the Transfer test, participants again applied force on a handgrip to win more money. This time, slot machines were presented with the Pavlovian cues, but with the outcomes hidden. The results indicated increased effort on the instrumental task, i.e., higher response frequency and greater force, in the presence of a reward-predicting cue. Our findings add to a growing number of studies demonstrating PIT effects in humans. This paradigm was proved to be useful in measuring the effects of a conditioned stimulus on behavioral activation.