Computational mechanisms underlying motivation to earn symbolic reinforcers.

Symbolic reinforcers, like money and points, play a critical role in our lives. Like rewards, symbolic reinforcers can be motivating and can even lead to compulsive behaviors like gambling addiction. However, we lack an understanding of how symbolic reinforcement can drive fluctuations in motivation. Here we investigated the effect of symbolic reinforcers on behaviors related to motivation during a token reinforcement learning task, using a novel reinforcement learning model and data from five monkeys. Our findings suggest that the value of a task state can affect willingness to initiate a trial, speed to choose, and persistence to complete a trial. Our model makes testable predictions for within trial fluctuations of neural activity related to values of task states.