Adaptation to motion presented with a tactile array

We investigated the effects of adaptation to 2 min of tactile apparent motion along the proximo-distal axis of the finger pad, produced with a vibrotactile array (Optacon), and developed a novel method to reveal the tactile motion aftereffect. Participants continuously reported perceived direction during adaptation to motion in the distal or proximal direction. The clarity of the direction percept weakened over time. Following this adaptation phase, participants judged the direction of a dynamic test stimulus composed of simultaneous motion in both directions. A tactile motion aftereffect (tMAE) resulted - the test stimulus was felt to move in the direction opposite to the adapting motion. The tMAE was robust to changes in the stimulus including speed and spatial features of the moving pattern, but there was a general bias to perceive distal motion. The implication for tactile devices is that motion signals should be brief and varied to avoid adaptation artifacts.