Investigating crossmodal influence between nociception and vision using temporal order judgments

Coordinating spatial perception between external space and body space is essential to adapt behaviors to objects, especially when these objects become noxious. Little is known about the crossmodal link between nociception/pain and vision. This study investigates how a nociceptive stimulus affects the perception of visual stimuli that are presented in the same side of space as the stimulated body part. In a temporal order judgment task, participants judged which of two visual stimuli, one applied to either side of space, had been perceived first. Visual stimuli were presented either near participants’ hands (peripersonal) or far from them (extrapersonal). Each pair of visual stimuli was preceded by either one nociceptive stimulus applied on one of the hands (unilateral) or two nociceptive stimuli, one applied to each hand at the same time (bilateral). Results show that, as compared to the bilateral condition, participants’ judgments were biased positively to the advantage of the visual stimuli having occurred in the same side of space as the hand on which the nociceptive stimulus was applied. Moreover, this effect seems larger when the visual stimuli were presented close to the hands. These results suggest that the perception of external space can be affected by the occurrence of highly significant bodily sensations such as pain, specifically when external sensory events occur in the peripersonal space.