Achronopresence: how temporal visuotactile and visuomotor mismatches modulate embodiment

Abstract

The loss of body ownership, the feeling that your body and its limbs no longer belong to you, presents a severe clinical condition that has proven difficult to study directly. We here propose a novel paradigm using mixed reality to interfere with natural embodiment using temporally conflicting sensory signals from the own hand. In Experiment 1 we investigated how such a mismatch affects phenomenological and physiological aspects of embodiment, and identified its most important dimensions using a principle component analysis. The results suggest that such a mismatch induces a strong reduction in embodiment accompanied by an increase in feelings of disownership and deafference, which was, however, not reflected in physiological changes. In Experiment 2 we refined the paradigm to measure perceptual thresholds for temporal mismatches and compared how different multimodal, mismatching information alters the sense of embodiment. The results showed that while visual delay decreased embodiment both while actively moving and during passive touch, the effect was stronger for the former. Our results extend previous findings as they demonstrate that a sense of disembodiment can be induced through controlled multimodal mismatches about one's own body and more so during active movement as compared to passive touch. Based on the ecologically more valid protocol we propose here, we argue that such a sense of disembodiment may fundamentally differ from disownership sensations as discussed in the rubber hand illusion literature, and emphasize its clinical relevance. This might importantly advance the current debate on the relative contribution of different modalities to our sense of body and its plasticity.

Weakening the subjective sensation of own hand ownership does not interfere with rapid finger movements

“…In keeping with previous findings [15,[48][49][50][51][52][53][54], we observed that the disintegration of visual, tactile and proprioceptive signals from participants' own hand resulted in a reduction in perceived ownership over that hand (S3). This was observed for both VT incongruent VP match and VT incongruent VP mismatch conditions.…”

“…We must consider the general lack of changes in skin conductance response to threat, our objective measure of changes in body ownership, following multisensory disintegration. Whilst this is in keeping with another recent study using a multisensory disintegration paradigm [53], it is in contrast to Gentile et al [48], who observed reductions in skin conductance response to threat in conditions inducing reductions in the sensation of own hand ownership. It is possible that this stems from differences between our paradigm and the one employed by Gentile et al [48].…”

“…We examined whether experimentally induced reductions in the sensation of ownership over the hand would interfere with rapid finger movements. As shown in previous studies https://doi.org/10.1371/journal.pone.0223580.g005 [15,[48][49][50][51][52][53][54], the disintegration of multisensory information from the hand resulted in a reduction in the subjective sensation of ownership. We replicated this finding in three experiments through the manipulation of visuotactile and visuoproprioceptive information, and built on previous work by examining the reaction time, acceleration, and velocity of rapid finger movements following multisensory disintegration.…”

“…Furthermore, the influence of body ownership on the cortical motor system described by aforementioned experimental articles should not only have functional relevance, but should also be evident in paradigms other than the rubber hand illusion. Previous research suggests that presenting individuals with incongruent multisensory information regarding their real body can reduce the subjective sensation of ownership over the body or reduce skin conductance response to threats [48][49][50][51][52][53][54], suggesting that the real body can be both explicitly and implicitly disowned in experimental settings, without 'replacing' it with a false limb. This might provide a more pure way of examining the role of body ownership in the movement of the real body.…”

The monologue of the double: allocentric reduplication of the own voice alters bodily self perception

“…These strong phenomenal descriptions however were not in line with the physiological measures, which might indicate that the effect was not as strong as in previously described multisensory illusions, but might also be linked to accumulating evidence not replicating the link between phenomenal alterations of the bodily self and physiological measures such as temperature (de Haan et al, 2017;Roel Lesur et al, 2020). Yet, in consistency with previous finings for experimentally induced autoscopy (Lenggenhager et al, 2007(Lenggenhager et al, , 2009Noel et al, 2015), we found changes in the location of self-identified extracorporeal cues.…”