The Improved Sensitivity to Crossmodal Asynchrony Caused by Voluntary Action: Comparing Combinations of Sensory Modalities

The brain has to assess the fine temporal relationship between voluntary actions and their sensory effects to achieve precise spatiotemporal control of body movement. Recently we found that voluntary action improved the subsequent perceptual temporal discrimination between somatosensory and auditory events. In voluntary condition, participants actively pressed a button and a noise burst was presented at various onset asynchronies relative to the button press. The participants made either ‘sound-first’ or ‘touch-first’ responses. We found that the temporal order judgment performance in the voluntary condition (as indexed by just noticeable difference) was significantly better than that when their finger was passively stimulated (passive condition). Temporal attention and comparable involuntary movement did not explain the improvement caused by the voluntary action. The results suggest that predicting sensory consequences via a ‘forward’ model enhances perceptual temporal resolution for precise control of the body. The present study examined whether this improved temporal sensitivity caused by the voluntary action is also observed for the other combinations of sensory modalities. We compared the effects of voluntary action on the temporal sensitivity between auditory-somatosensory, visual-somatosensory, and somatosensory-somatosensory stimulus pairs