Informative vision alters tactile perception

Previous studies have shown that individuals are more likely to detect a near-threshold tactile stimulus when seeing touch at the same location, leading to the hypothesis that informative vision enhances tactile perception. However, such results could also be explained by a more liberal response criterion when seeing touch. To examine if viewed touch enhances tactile perception, we presented participants with two tasks. Vibrotactile stimuli were presented at varying intensities to both the index and ring finger while participants watched videos of a hand being touched on one cued finger. In the comparative judgment task, participants indicated which finger received the more intense tactile stimulus on their own hand. Across multiple experiments, participants consistently demonstrated a shifted point of subjective equality, reporting that the tactile stimulus associated with the cued finger was more intense. These results provide evidence that the cue clearly altered performance but are agnostic regarding whether there was a shift in response bias or perceptual enhancement. In the equality judgment task, which is more resistant to response bias, participants indicated whether the stimulus intensities on their fingers were the same or different while watching the videos. For equality judgment performance, we found evidence for noise processes at the tails, as participants were more likely to judge tactile stimuli as equal when they were either near threshold or well-above threshold. For stimuli outside of this noise regime, we found a significant shift in the peak of the equality judgment curve (alpha) such that participants were most likely to respond ‘equal’ when the cued stimulus was less intense than the uncued stimulus. These findings suggest that viewing informative touch enhances tactile perception.