Body ownership increases the interference between observed and executed movements

Abstract

When we successfully achieve willed actions, the feeling that our moving body parts belong to the self (i.e., body ownership) is barely required. However, how and to what extent the awareness of our own body contributes to the neurocognitive processes subserving actions is still debated. Here we capitalized on immersive virtual reality in order to examine whether and how body ownership influences motor performance (and, secondly, if it modulates the feeling of voluntariness). Healthy participants saw a virtual body either from a first or a third person perspective. In both conditions, they had to draw continuously straight vertical lines while seeing the virtual arm doing the same action (i.e., drawing lines) or deviating from them (i.e., drawing ellipses). Results showed that when there was a mismatch between the intended and the seen movements (i.e., participants had to draw lines but the avatar drew ellipses), motor performance was strongly “attracted” towards the seen (rather than the performed) movement when the avatar’s body part was perceived as own (i.e., first person perspective). In support of previous studies, here we provide direct behavioral evidence that the feeling of body ownership modulates the interference of seen movements to the performed movements.

Virtual training leads to real acute physical, cognitive and neural benefits on healthy adults: study protocol for a randomized-controlled trial

“…The background of this RCT protocol study starts with two assumptions, based on data presented in literature: 1) HIE has acute beneficial consequences on executive functions and their neural basis (17,68); 2) the movements of the own virtual body can generate measurable consequences on the real body, comparable to ones when we actually move (33,41).…”

“…In this study, we combine the efficacy of the HIE on cognitive functions (17) with the possibility of manipulating SoBO and SoA offered by IVR (33,41). Our goal is to demonstrate whether a virtual HIEbased intervention performed exclusively by the considered-as-own virtual body, while the real subject's body is totally still (hereinafter vHIE), has acute cognitive and somatic beneficial effects on the real body, comparable to the ones that arise after an actual physical training.…”

“…Several recent papers shown that not only the simple display of an avatar in first-person perspective (1PP) creates the illusory sense of body ownership (SoBO) over the virtual body (38)(39)(40) but also its movements create the illusory sense of agency (SoA) over them (32,33,41); the actions performed by the own virtual body are subjectively considered as own generated and they arise subjective, behavioral and physiological reactions in the real subject's body perfectly analogous to what happens in the physical world (32,33). For example, when the movements of the own virtual body do not match the real ones, an unconscious adjustment of the actual performance occurred, driven by the sense of body ownership over the avatar (41).…”

“…Several recent papers shown that not only the simple display of an avatar in first-person perspective (1PP) creates the illusory sense of body ownership (SoBO) over the virtual body (38)(39)(40) but also its movements create the illusory sense of agency (SoA) over them (32,33,41); the actions performed by the own virtual body are subjectively considered as own generated and they arise subjective, behavioral and physiological reactions in the real subject's body perfectly analogous to what happens in the physical world (32,33). For example, when the movements of the own virtual body do not match the real ones, an unconscious adjustment of the actual performance occurred, driven by the sense of body ownership over the avatar (41). But even in absence of actual movements, so if the virtual body moves while the real body is totally still, the illusion can trigger measurable reactions perfectly comparable to the ones during an actual movement execution, online (33,41) or in terms of consequences (32,42,43): interestingly for our purposes, it has been shown that if the virtual body, displayed in 1PP, climbs a hill, in the real participant's body the heart rate (HR) increases, exactly as it happens in the physical world, but in this case it seems to be a physiological counterpart of the SoBO visual illusion (33).…”

“…For example, when the movements of the own virtual body do not match the real ones, an unconscious adjustment of the actual performance occurred, driven by the sense of body ownership over the avatar (41). But even in absence of actual movements, so if the virtual body moves while the real body is totally still, the illusion can trigger measurable reactions perfectly comparable to the ones during an actual movement execution, online (33,41) or in terms of consequences (32,42,43): interestingly for our purposes, it has been shown that if the virtual body, displayed in 1PP, climbs a hill, in the real participant's body the heart rate (HR) increases, exactly as it happens in the physical world, but in this case it seems to be a physiological counterpart of the SoBO visual illusion (33). In summary, IVR can provide effective investigating methods to better understand the relationship between sense of body ownership and sense of agency (44) and can provide potential solutions, complementary to the existing ones, for clinical population (see 43 for a review).…”