Haptic Illusions Induced by Tactile Flow

In this paper we report on a set of experiments involving perceptual illusions elicited by dynamic tactile stimulation of fingertips. These misperceptions are akin to some well studied optical illusions, which have been given an explanation in terms of the mechanisms of optic flow perception. We hypothesize that a similar perceptual mechanism exists for tactile flow, which is related to how humans perceive relative motion and pressure between the fingertips and objects in contact. We present a computational model of tactile flow, and discuss how it relates to accepted models of the neurophyisiology of touch. A particularly interesting phenomenon observed under some experimental circumstances, consisting of an incoherent tactile perception generating what we call a tactile vertigo, can be explained in terms of this model. The proposed tactile flow model also explains other phenomena observed in the past (namely, the Contact Area Spread Rate effect), and is of importance in designing simpler, more effective devices for artificial haptic sensing and displays.