Understanding components of embodiment: Evidence from the mirror box illusion.

Past studies have examined embodiment in the rubber hand illusion, using principal components analysis (PCA) to identify factors from questionnaire responses during synchronous and asynchronous stroking. To better understand the phenomenology of embodiment, we used PCA in the mirror box illusion to examine performance across conditions that varied in movement synchrony to examine multisensory integration and movement type to vary the amount of multisensory congruence. We found three dissociable components in all conditions: embodiment, deafference and attentiveness. We also examined how these embodiment ratings varied across the four conditions. As hypothesized, embodiment ratings were highest for synchronous movement, with feelings of deafference highest for asynchronous movement. Furthermore, there was a movement by timing interaction, such that sliding resulted in greater differences in synchronous versus asynchronous ratings than tapping. These results suggest that embodiment or deafference can be changed as a function of the amount of multisensory congruence.