Cross-Modal Transfer of the Tilt Aftereffect From Vision to Touch.

Dafni Krystallidou,Peter Thompson

doi:10.1177/2041669516668888

Abstract

Visual input powerfully modulates the dynamics of tactile orientation perception. This study investigated the transfer of the tilt aftereffect (TAE) from vision to somatosensation. In a visual tilt adaptation paradigm, participants were exposed to clockwise or anticlockwise visual tilt, followed by three brief tactile two-point stimuli delivered on their forehead. In a two-alternative forced choice task, participants had to indicate whether the haptic stimulus was tilted to the right or left. Repeated exposure to oriented visual gratings produced a tactile TAE, such that the subsequent tactile stimuli appeared tilted toward the opposite direction. To assess the origin of this effect, the experiment was repeated with the head tilted. Adaptation to a gravitationally tilted grating but with the head tilted so that the grating was retinally vertical induced a robust tactile aftereffect suggesting that the visuotactile TAE is due to spatiotopic rather than retinotopic adaptation.

Highlights

Visual aftereffects refer to adaptation-induced illusory changes in visual perception and provide a powerful tool for elucidating the neural locus of complex visual processing (Zhao, Series, Hancock, & Bednar, 2011)
Psychometric functions were plotted for each participant, and the point of subjective vertical (PSV) determined by fitting a cumulative normal distribution to the data; 95% confidence intervals were fitted by a standard bootstrapping procedure. These results demonstrate that adaptation to a tilted visual stimulus can shift our perception of the vertical in the haptic domain just as it can in the visual domain—the traditional tilt aftereffect
To determine the reference frame of the visual-to-tactile tilt aftereffect (TAE), we introduced a discrepancy between the gravitational and the egocentric visual vertical by having observers adapt to visual gratings with their heads tilted, by the same angle and direction as the visual adaptor, so that the visually projected gratings were vertical on the retina but gravitationally they remained tilted

Summary

Introduction

Visual aftereffects refer to adaptation-induced illusory changes in visual perception and provide a powerful tool for elucidating the neural locus of complex visual processing (Zhao, Series, Hancock, & Bednar, 2011). In the case of the tilt aftereffect (TAE), prolonged exposure to tilted visual gratings (10–30 from vertical) causes a subsequently presented vertical line or grating (test stimulus) to be perceived as being tilted in the opposite direction (Gibson & Radner, 1937) This perceptual phenomenon has been often attributed to lateral interactions between orientation-selective mechanisms at an early stage of visual processing (Tolhurst & Thompson, 1975). Matsumiya (2013) demonstrated that adaptation to a visually presented face belonging to a specific facial expression (happy or sad) elicits a repulsive bias in the subsequent perception of a haptically perceived neutral face and vice versa Together, these studies illustrate that tactile processing depends on mechanisms adapted by vision, suggesting that visual stimulation can alter tactile processing

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