Abstract
Neuromodulatory signals such as reward and arousal modulate visual perceptual learning (VPL). Two hypotheses could explain how reward and arousal modulate VPL. A goal-dominance model predicts that reward or arousal enhance visual features relevant to the current goal and inhibit irrelevant features. Conversely, a state-dominance model predicts that reward or arousal enhance visual features irrespective of their relevance to the current goal. To test which of these models is consistent with the effects of reward and arousal on VPL, we trained three participant groups (Reward, Arousal and Control groups) over the course of 5 daily sessions on a VPL task, consisting of a Gabor patch presented in the upper left or lower right visual quadrant. The Gabor had one of two orientations (2.5 degree left or right tilted from vertical) and one of several contrast levels. Participants were instructed to categorize the Gabor based on contrast level, while maintaining central fixation (eye-tracking was conducted). The orientation of the Gabor was task-irrelevant. Unknown to the participants, monetary reward was paired 80% of the times with one of the orientations in the Reward group while an arousing beep was paired in the Arousal group. The reward group was instructed that reward was given when they maintained good fixation. No neuromodulatory signal was provided in the Control group. Before the first and after the final training session, participants performed an orientation discrimination task on different contrast levels in both quadrants. Participants’ performance decreased for the paired orientation in the Reward group, whereas performance enhanced for both the paired and unpaired orientations in the Arousal group. There were no performance changes in the Control group. These results indicate that the effects of reward on VPL are consistent with a goal-dominance model, whereas the effects of arousal on VPL are consistent with a state-dominance model.