Abstract
Motivation and reward are known to facilitate the development of our adaptive behavior. Recent literatures have suggested that learning to associate visual feature with reward increases its visual saliency. However, it remains unclear whether reward learning can prompt the consolidation of visual representation and makes the visual feature better accessible in working memory. To establish a reward-color association, our observers were trained on a visual search task. During the training, eight bars inside colored circles were shown for 500 ms at equal eccentricity around the central fixation. The bar with odd orientation was the target and appeared only inside red or green circle. Correct response was associated with high probability (80%) of high monetary reward in one condition (e.g., red circle) and high probability (80%) of low monetary reward in the other condition (e.g., green circle). Before and after the training, we estimated the reward effect on visual short-term memory with a change detection paradigm. Eight bars differed in orientation and color were shown and observers were to determine whether the probed bar had rotated by 90 degree between sample and test displays. The sample display was shown for 500 ms and followed by a blank interval (1000 – 2500 ms) before the test display appeared. Performance improvement in detection sensitivity (d’) was calculated. The results show significantly larger improvement in sensitivity if target’s color was associated with high reward compared to low reward (p<0.05) and no reward (p<0.05) during the training, despite the fact that reward-associated feature (i.e., color) was implicitly learned and tested in the absence of task-relevance. No significant effect of reward in shift of decision criterion is found. Our findings demonstrate an important role of reward association in visual short-term memory consolidation. This effect exists even if the association is implicitly learned.
Meeting abstract presented at VSS 2012