Tactile distances are greatly underestimated in perception and motor reproduction

Tactile distance perception typically requires the integration of tactile speed over time. In this study, we investigated tactile distance perception by comparing subjects' ability to reproduce tactile distance by moving the hand, and compared this to their ability to estimate the magnitude of sliding distance. This is the first investigation of subjects' ability to use motor reproduction to reproduce the same tactile distance that was felt during passive sliding contact. To clarify the role of vibrotactile information in sliding distance perception, we investigated tactile distance perception by manipulating tactile mechanical signals in two different ways: by adding mechanical noise to the finger, or by sensing and amplifying vibrotactile signals in the finger. In our experiment, subjects systematically underestimated tactile sliding distance. On average, they reproduced 55% of the actual distance. Responses on the magnitude estimation and the distance reproduction tasks were highly similar. Subjects estimated sliding distance to be significantly longer when tactile signals were manipulated compared to no vibrotactile manipulations, although mechanical noise impaired distance perception accuracy. These results suggest that further research is needed in order to clarify the effect of underestimation of tactile distance on fine motor tasks guided by touch.