The Virtual Hand Illusion in Obesity: Dissociation Between Multisensory Interactions Supporting Illusory Experience and Self-Location Recalibration

Abstract

<jats:title>Abstract</jats:title> <jats:p>The Rubber Hand Illusion (RHI) is used widely to investigate the multisensory integration mechanisms that support bodily self-consciousness and, more specifically, body ownership and self-location. It has been reported that individuals affected by obesity show anomalous multisensory integration processes. We propose that these obesity-induced changes could lead to an unusual susceptibility to the RHI and anomalous bodily self-experience. To test this hypothesis, we administered a modified version of the RHI (using a picture of the participant’s hand) to individuals affected by obesity and participants with a healthy weight. During synchronous and asynchronous stimulation, we compared the subjective experience of the illusion (using a questionnaire) and the effect of the illusion on self-location (i.e., proprioceptive drift). In accordance with the illusion phenomenology, both groups had a comparable subjective illusory experience after the synchronous stimulation. Nevertheless, individuals affected by obesity showed less recalibration of self-location than healthy weight participants. In light of a recent interpretation of the multisensory integration mechanisms that underpin the RHI, our findings suggest that in obesity visuo-tactile integration supporting the subjective experience of the illusion is preserved, whereas visuo-proprioceptive integration for self-location is reduced.</jats:p>

Body illusions for mental health: a systematic review

“…Seven studies used BIs toward a body part to investigate alterations in body representation in patients with eating disorders (ED) compared to a healthy control group (Carey & Preston, 2019;E. Eshkevari et al, 2012;Ertimiss Eshkevari et al, 2014;Keizer et al, 2014;Tagini et al, 2020;Zopf et al, 2016). Specifically, a significant reduction in hand size estimation and low levels of both implicit and explicit body satisfactions have been shown when using the moving rubber hand illusion (Carey & Preston, 2019).…”

“…In their study, Zopf and colleagues (2016) used the RHI to test whether body localization abilities are altered in patients with AN compared to a healthy control group: patients with AN displayed a compromised proprioceptive encoding of hand location (Zopf et al, 2016). In addition, Tagini and collegaues (2020), used the VHI in participants affected by obesity and participants with a healthy weight, to observe a possible unusual susceptibility to the RHI related to anomalous bodily self-experience, and found that even though participants with obesity reported a strong ownership illusion, a reduction in recoding self-location was also observed (Tagini et al, 2020).…”

“…Thakkar et al, 2011;Van Haren et al, 2018), as well as an altered self-recognition (Sandsten et al, 2020), and the way in patients with schizophrenia discriminate others (Ferroni et al, 2019). Moreover, BIs have been also used in patients with eating disorders (Carey and Preston, 2019;Eshkevari et al, 2012Eshkevari et al, , 2014Keizer et al, 2014;Tagini et al, 2020;Zopf et al, 2016;Forghieri et al, 2016;Keizer et al, 2016), in which inner body perception is often disturbed presenting distortions or mismatches in discriminating how the body is perceived and how physically it is (Malighetti et al, 2020). In this regard, BIs have been used to show alterations in body perception in patients with EDs compared to a healthy controls (Carey & Preston, 2019;E.…”

“…In this regard, BIs have been used to show alterations in body perception in patients with EDs compared to a healthy controls (Carey & Preston, 2019;E. Eshkevari et al, 2012;Ertimiss Eshkevari et al, 2014;Keizer et al, 2014;Tagini et al, 2020;Zopf et al, 2016), as well as to modulate body size estimation of real body parts that are more emotionally salient (e.g. shoulders, abdomen, hips) in patients with AN (Keizer et al, 2016).…”

Illusory Body Ownership Affects the Cortical Response to Vicarious Somatosensation

“…Visual stimuli consisted of videos displayed via MR-compatible goggles, placed at 3–5 cm in front of the participant’s eyes, and adjusted to achieve a clear dual-view image covering the entire visual field (Resonance Technology, Inc.). According to the VHI procedure, the videos showed a virtual right human hand being brushed by a paintbrush ( Tagini et al. 2019 ; Pyasik et al.…”