When a rubber hand ‘feels’ what the real hand cannot

Abstract

We examined a patient who was clinically much better at reporting tactile stimulation when he could see his stimulated hand. Experimentally, we found that he had difficulty detecting taps accompanied by a salient (but not predictive) light located directly above his concealed hand. However, his performance was dramatically improved if the light was attached to a rubber hand situated in line with the patient's hidden hand. Previous studies have suggested that tactile sensitivity can be improved by nearby visual stimulation. However, our effect shows that crossmodal sensory facilitation does not only depend upon simple spatial proximity alone. Rather, a simultaneous visual event dramatically improves perception of touch specifically when it is attributed to the perceiver's stimulated limb.

Multisensory integration in the Müller-Lyer illusion: From vision to haptics

“…Specifically, they might use tactile information about the midpoint of the line to correct the shift produced by the visual arrowheads. Evidence from brain-damaged patients (Rorden, Heutink, Greenfield, & Robertson, 1999) and neurologically unimpaired participants (Serino, Padiglioni, Haggard, & Ladavas, 2009;Taylor-Clarke, Kennett, & Haggard, 2002), indicates that vision may improve tactile detection, supporting an interpretation of this sort for the present observation that in the bimodal visuohaptic condition the illusory "error" is reduced in size.…”

Illusory touch and tactile perception in somatoform dissociators

“…This observed increase in tactile sensitivity is likely due to participants directing attention towards the site of stimulation. A neutral visual stimulus presented on or near a body part can lead to a shift in attentional focus toward that area [41], and it has been demonstrated that even noninformative vision can decrease tactile thresholds and increase spatial resolution for touch sensation when attention is directed toward the stimulated arm [42][43][44].…”

Development of a paradigm for measuring somatic disturbance in clinical populations with medically unexplained symptoms

“…Multisensory research indicates that a neutral visual stimulus, such as a light flash, can lead to a tactile attention shift toward a nearby body part [13] and that noninformative vision can decrease a patient's threshold for touch sensation (see Refs. [14,15]). When checking for signs of illness, patients with MUS are commonly reported to use visual inspection (e.g., mirror gazing).…”