Understanding embodiment: the structural components of the mirror box illusion experience, and the necessary conditions for embodiment to occur

Abstract

Firstly, understanding what it is like to have a body is a fundamental question as our body is central to our cognition, but complex to answer as we always have an experience of a body. To understand embodiment’s phenomenology, we used a psychometric approach to the mirror box illusion (MBI), which shifts participant’s experience of body to a reflected hand in a mirror using visuomotor and visuotactile congruence. Additionally, we explored if the structure of the experience of the MBI was similar to the rubber hand illusion’s, which lacks motor movement (Longo et al., 2008). ☐ Secondly, body ownership models, informed by the rubber hand illusion, have proposed that biomechanical possibility is necessary for embodiment. We used the mirror box illusion to examine whether this is true. In four studies, participants viewed a biomechanically impossible (i.e. 180-degree rotated) hand reflection in a mirror directly facing them and received unseen tactile stimulation on their hand. They were then asked whether they felt their hand/touch in the mirror location. The biomechanically impossible hand was embodied in approximately half of all trials, providing evidence that embodiment can occur even when anatomical constraints are violated. The realistic nature of the mirror hand may outweigh biomechanical impossibility, resulting in the illusion. When embodying the mirror hand, participants perceived a touch in the mirror location on approximately one-third of trials. These results demonstrate that ownership and referred tactile sensations are separable phenomena and suggest that more evidence is necessary to shift the perceived location of touch than body ownership.