Effects of unconscious action learning on action and perception

Abstract

Perception learning is a way to improve people’s sensory ability by extensive training. Researchers have been investigating the specificity of perceptual learning and the extent to which it can be transferred to untrained features or locations for decades. It is still unclear whether or not learning can transfer across the two visual pathways: the ventral pathway mediating visual perception and the dorsal pathway mediating visuomotor skills. If action learning could transfer to visual perception or vice versa, then we can use this transfer to design training protocols to help patients with either ventral or dorsal lesions. Given that patients with ventral lesions usually have deficits in visual perception, to mimic the situation of this kind of patient, we made stimuli (a long and narrow rectangle frame, either horizontal or vertical) invisible with continuous flash suppression (CFS) and trained participants to pretend to insert a card into the frame (action learning). Participants were tested before, four days after, or eight days after training. There were three kinds of tests, a sensitivity test which tests the contrast at which the orientation of the frame could be recognized at 75% accuracy, an action test in which participants were asked to post the card into the frame, and a perception test in which participants were asked to verbally report the orientation of the frame. We found that after eight days of training, participants’ performance in all three tasks was improved. The amount of action and perception improvement was correlated with each other. The amount of perception improvement after action learning was correlated with the depth of unconsciousness (i.e., the ratio of stimulus contrast to the contrast threshold of each participant before training). Overall, our study suggests that the learning effect can transfer across the two pathways.