Abstract
It is assumed that reward signal gates visual perceptual learning (Roelfsema, Ooyen and Watanabe, 2009). However, it remains unclear whether such gating effect can be dissociated from attentional biases. Here we investigate this issue using unconsciously perceived monetary reward during motion perceptual learning. Seventeen subjects were trained to detect coherent motion of two directions for four daily sessions. During the training, one motion direction was paired with subliminally presented high-value reward, and the other direction was paired with subliminally presented low-value reward. In order to maintain subjects’ attention on the subliminal reward feedback, catch trials in which reward feedback was replaced by visible checkerboard were inserted in the training. Subjects were instructed to detect these occasionally presented checkerboards. Before and after the training, we measured subjects’ psychometric functions on two trained motion directions. Changes in detection threshold and slope at 75% accuracy level were calculated. We also measured subjects’ awareness level of reward value and recognition level of reward-direction contingencies. The results showed that decrease of the detection threshold was significantly larger for the motion direction paired with high reward value compared to the direction paired with low reward value (p<0.05). The increase of the slope of the psychometric function was also significantly larger for the high reward direction compared to the low reward direction (p<0.05). The reward effect on perceptual learning could not be explained by attentional biases. Awareness tests before and after the training indicated that subjects were unconscious of the reward value and the reward-direction contingencies. Our findings suggest that reward signal promotes motion perceptual learning, even if the reward feedback was unconsciously perceived.
Meeting abstract presented at VSS 2013