Visual Capture of Touch: Out-of-the-Body Experiences With Rubber Gloves

Abstract

When the apparent visual location of a body part conflicts with its veridical location, vision can dominate proprioception and kinesthesia. In this article, we show that vision can capture tactile localization. Participants discriminated the location of vibrotactile stimuli (upper, at the index finger, vs. lower, at the thumb), while ignoring distractor lights that could independently be upper or lower. Such tactile discriminations were slowed when the distractor light was incongruent with the tactile target (e.g., an upper light during lower touch) rather than congruent, especially when the lights appeared near the stimulated hand. The hands were occluded under a table, with all distractor lights above the table. The effect of the distractor lights increased when rubber hands were placed on the table, "holding" the distractor lights, but only when the rubber hands were spatially aligned with the participant's own hands. In this aligned situation, participants were more likely to report the illusion of feeling touch at the rubber hands. Such visual capture of touch appears cognitively impenetrable.

Hands up: Attentional prioritization of space near the hand.

“…As a result, the visual information regarding the fake hand location, rather than the real hand location, combined with the visual information was able to elicit the facilitated target detection. Thus, the present findings are consistent with studies such as Pavani et al (2000). Pavani et al used a paradigm in which the visual location of a rubber hand competed with the location of a hidden, real hand.…”

Visual enhancement of touch and the bodily self

“…This is consistent with the claim of that synchronous stroking is a necessary prerequisite of the RHI. This hypothesis is at odds, however, with the findings of at least two studies that have reported significant effects of seeing a rubber hand without any stroking whatsoever (Farnè, Pavani, Meneghello, & Làdavas, 2000;Pavani, Spence, & Driver, 2000). We suggest that there may be (at least) two independent causes of the RHI: one driven purely by visual perception of the rubber hand in the proper position and orientation, another driven by the synchronous stroking of the participants' and the rubber hand.…”

Bodily ownership and self-location: Components of bodily self-consciousness

“…If this were the case, signals from any external object could potentially be integrated with bodily-related signals inducing a sense of ownership for that object. However, this does not normally occur, since the RHI is not induced (or it is much weaker) when visuo-tactile stimulation is applied to a non-corporeal object (Armel & Ramachandran, 2003;Haans, Ijsselsteijn, & de Kort, 2008;Tsakiris, Carpenter, James, & Fotopoulou, 2010;Tsakiris & Haggard, 2005) or when the rubber hand is placed in a position that is anatomically incompatible with the subject's posture (Costantini & Haggard, 2007;Lloyd, 2007;Pavani, Spence, & Driver, 2000). Tsakiris and Haggard (2005) and more recently Tsakiris (2010) argued that the sense of body ownership also depends on top-down processes, which act over and above multisensory integration mechanisms and help distinguish between objects that can and cannot be attributed to one's body as a function of their visual appearance and anatomical coherence with the physical body.…”