The Effect of Visual, Spatial and Temporal Manipulations on Embodiment and Action

Abstract

The feeling of owning and controlling the body relies on the integration and interpretation of sensory input from multiple sources with respect to existing representations of the bodily self. Illusion paradigms involving multisensory manipulations have demonstrated that while the senses of ownership and agency are strongly related, these two components of bodily experience may be dissociable and differentially affected by alterations to sensory input. Importantly, however, much of the current literature has focused on the application of sensory manipulations to external objects or virtual representations of the self that are visually incongruent with the viewer’s own body and which are not part of the existing body representation. The current experiment used MIRAGE-mediated reality to investigate how manipulating the visual, spatial and temporal properties of the participant’s own hand (as opposed to a fake/virtual limb) affected embodiment and action. Participants viewed two representations of their right hand inside a MIRAGE multisensory illusions box with opposing visual (normal or grossly distorted), temporal (synchronous or asynchronous) and spatial (precise real location or false location) manipulations applied to each hand. Subjective experiences of ownership and agency towards each hand were measured alongside an objective measure of perceived hand location using a pointing task. The subjective sense of agency was always anchored to the synchronous hand, regardless of physical appearance and location. Subjective ownership also moved with the synchronous hand, except when both the location and appearance of the synchronous limb were incongruent with that of the real limb. Objective pointing measures displayed a similar pattern, however movement synchrony was not sufficient to drive a complete shift in perceived hand location, indicating a greater reliance on the spatial location of the real hand. The results suggest that while the congruence of self-generated movement is a sufficient driver for the sense of agency, the sense of ownership is additionally sensitive to cues about the visual appearance and spatial location of one’s own body.

Pins & Needles: Towards Limb Disownership in Augmented Reality

“…While research into the sense of agency has managed to address this by experimentally modulating a loss of control (48-51) (Franck et al, 2001;Kannape & Blanke, 2013;Leube et al, 2003;Nielsen, 1963), a symptom that is often found in clinical conditions (see e.g. (Blakemore, Wolpert, & Frith, 2002)), ownership studies have instead investigated the opposite: a 'positive' ownership of an artificial limb such as a rubber hand or foot (Bigna Lenggenhager, Hilti, & Brugger, 2015), or even two versions of one's own hand (Ratcliffe & Newport, 2017) (an interesting conundrum of this study is that the 'fake' hand is actually based on the participant's own hand, leading to the question of whether one can disown one representation of one's hand over another). Analog to sensorimotor studies delineating the spatiotemporal limits of agency, we have here introduced a paradigm to directly induce disownership of one's own limb: where participants report a loss of control over their actions in agency research, participants in the ReHI perceive a weakened ownership over their own hand and arm.…”

“…Next to our understanding of the nature of bodily self-consciousness and its disorders , these data contribute towards developing methods to restore the bodily self where it is disturbed (G. L. Moseley, 2007;Pazzaglia, Haggard, Scivoletto, Molinari, & Lenggenhager, 2016). Strikingly however, most studies using multisensory stimulation in healthy participants or patients targeted the manipulation to bodily ownership of an additional and external, fake or virtual body (part), or more recently, two virtual representations of one's own limb (Newport & Preston, 2011;Ratcliffe & Newport, 2017). In the above-described rubber hand illusion (RHI), the most striking phenomenological perception is not the feeling of disownership of the real hand but the feeling of ownership for the supernumerary rubber hand.…”

Rubber Hand Illusion does not arise from comparisons with internal body models: a new multisensory integration account of the sense of ownership

“…According to Tsakiris (2010), the filter operates in a 304 gradual rather than a bottleneck fashion: "the more the viewed object matches the structural 305 appearance of the body-part's form, the stronger the experience of body-ownership will be" (p. 306 707). Consistently, a gradual reduction in the strength of the feeling of ownership is sometimes 307 reported with the distortions of the appearance of the hand (e.g., Ratcliffe & Newport, 2017). 308 2 Note that the predictive processing framework may predict the exclusion of some body properties from the body model; a continuously adapting and liberal model would be more functional in the case of constantly changing body properties (e.g., hand size changes when one puts on weight, skin color temporarily changes from bruises and sun exposition, etc).…”

Peer Review #2 of "Illusory resizing of the painful knee is analgesic in symptomatic knee osteoarthritis (v0.1)"

“…Manuscript to be reviewed the sense of ownership in multisensory illusions is additionally sensitive to cues about visual appearance and spatial location when those illusions are applied to one's own body (Ratcliffe & Newport 2017). Further, the present incongruent VT condition may be argued to have spatial congruence (the hand is located and tactile input occurs at the visually seen location on the leg) and temporal congruence (tactile input occurs at the same time the visual change occurs), but not tactile directional congruence (the tactile input does not match the direction of visual change).…”