Motion Aftereffects Transfer between Touch and Vision

Current views on multisensory motion integration assume separate substrates where visual motion perceptually dominates tactile motion [1, 2]. However, recent neuroimaging findings demonstrate strong activation of visual motion processing areas by tactile stimuli [3-6], implying a potentially bidirectional relationship. To test the relationship between visual and tactile motion processing, we examined the transfer of motion aftereffects. In the well-known visual motion aftereffect, adapting to visual motion in one direction causes a subsequently presented stationary stimulus to be perceived as moving in the opposite direction [7, 8]. The existence of motion aftereffects in the tactile domain was debated [9-11], though robust tactile motion aftereffects have recently been demonstrated [12, 13]. By using a motion adaptation paradigm, we found that repeated exposure to visual motion in a given direction produced a tactile motion aftereffect, the illusion of motion in the opponent direction across the finger pad. We also observed that repeated exposure to tactile motion induces a visual motion aftereffect, biasing the perceived direction of counterphase gratings. These crossmodal aftereffects, operating both from vision to touch and from touch to vision, present strong behavioral evidence that the processing of visual and tactile motion rely on shared representations that dynamically impact modality-specific perception.