The haptic analog of the visual Aubert-Fleischl phenomenon

Abstract

In vision, the perceived velocity of a moving stimulus is different depending on whether the image moves across the retina with the eyes immobile or whether the observer pursues the stimulus such that the stimulus is stationary on the moving retina. The effect is known as the Aubert-Fleischl phenomenon. Here, we reproduced the analog of this visual illusion in haptics. For this purpose, we asked our participants to estimate the speed of a moving belt either from tactile cues, by keeping the hand world stationary, or from proprioceptive cues by tracking the belt with a guided upper-limb movement. The participants overestimated the speed of the moving stimulus determined from tactile cues compared with proprioceptive cues, in analogy with the Aubert-Fleischl phenomenon. Reproducing the illusion in the haptic modality may help evaluating some of the general mechanisms of spatial constancy in perceptual systems.