Examining the effects of reward and punishment on incidental learning

Reward has been shown to improve multiple forms of learning. However, many of these studies do not distinguish whether reward directly benefits learning or if learning is boosted by modulation of top-down factors such as attention and motivation. The work outlined in this dissertation explores the modulatory effects of reward and punishment without directly manipulating top-down factors such as attention or motivation. We achieved this goal by studying the effects of reward and punishment on incidental learning – a branch of procedural learning where learning occurs without intention and through repetition. Our results reveal that reward is able to bolster incidental learning during the performance and learning of an associative task, even when awareness of how to achieve the reward is minimized (Experiments 1 and 2). However, a similar benefit was not observed in an analogous set of experiments examining the effect of punishment on incidental learning (Experiments 3 and 4). A direct comparison between the effect of reward and punishment on incidental learning revealed a significant advantage for rewarded combinations over punishment. However, this advantage was only observed when high cognitive (associative) demands were emphasized (Experiment 6), as opposed to high motor demands (Experiment 5). Finally, we explored the role of dopamine in the effect of reward on incidental learning. Because dopamine neuron dynamics have been implicated in both reward processing and in various forms of learning, we hypothesized that patients with Parkinson's disease (PD), who experience an accelerated rate of death of dopamine neurons, would experience impaired learning from rewards compared to healthy older adults. Experiment 7 revealed a significant impairment in reward-related incidental learning for patients with Parkinson's disease relative to comparisons. The amount of levodopa medication taken by PD patients predicted the effect of reward, demonstrating a potential link between dopamine levels and the effect of reward on incidental learning. Together, this dissertation demonstrates that 1) reward improves incidental learning, 2) reward may be an exceptional form of feedback, as opposed to punishments, and 3) dopamine levels may potentially drive the effect of reward on incidental learning