Tactile afference in online movement guidance to a body location

Like visual motion, tactile motion conveys the direction and magnitude of target change (e.g., when catching a slipping towel on the body). Despite the lower density of tactile vs. visual receptors (Johansson & Vallbo, 1979; Osterberg, 1935) and shorter detection latencies for tactile vs. visual stimuli (Ng & Chan, 2012), tactile motion has been hypothesized to yield comparable processes to visual motion (e.g., Pack & Bensmaia, 2015). The purpose of our experiment was to compare the latency and magnitude of corrections to a moving tactile or visual target. If comparable processes take place during visual and tactile target motion, then the lower density of tactile receptors should yield smaller correction amplitudes but no differences in the latency of corrections. Participants made reaching movements to an LED or a myofilament touching the non-reaching finger. In one-third of the trials, the target was displaced either 3-cm away or toward the participant, 200 ms after movement onset. Participants were instructed to adjust their trajectories towards the new target location. The results for the correction latencies did not yield significant differences between the tactile and visual targets. However, when the target was perturbed toward the participant, there were larger correction magnitudes in the visual than the tactile target condition. These findings support the hypothesis that moving tactile and visual stimuli can yield comparable processes. Also, these findings complement other research showing that moving the target hand yield earlier and larger corrections than moving a visual target (Manson et al., 2019). Hence, not all corrections to non-visual targets are controlled for in the same manner.