Tactile Slip and Hand Displacement: Bending Hand Motion with Tactile Illusions

Touch provides an important cue to perceive the
physical properties of the external objects. Recent studies
showed that tactile sensation also contributes to our sense of
hand position and displacement in perceptual tasks. In this
study, we tested the hypothesis that, sliding our hand over
a stationary surface, tactile motion may provide a feedback
for guiding hand trajectory. We asked participants to touch
a plate having parallel ridges at different orientations and to
perform a self-paced, straight movement of the hand. In our
daily-life experience, tactile slip motion is equal and opposite
to hand motion. Here, we used a well-established perceptual
illusion to dissociate, in a controlled manner, the two motion
estimates. According to previous studies, this stimulus produces
a bias in the perceived direction of tactile motion, predicted by
tactile flow model. We showed a systematic deviation in the
movement of the hand towards a direction opposite to the one
predicted by tactile flow, supporting the hypothesis that touch
contributes to motor control of the hand. We suggested a model
where the perceived hand motion is equal to a weighted sum
of the estimate from classical proprioceptive cues (e.g., from