The structure of conscious bodily self-perception during full-body illusions

Previous research suggests that bodily self-identification, bodily self-localization, agency, and the sense of being present in space are critical aspects of conscious full-body self-perception. However, none of the existing studies have investigated the relationship of these aspects to each other, i.e., whether they can be identified to be distinguishable components of the structure of conscious full-body self-perception. Therefore, the objective of the present investigation is to elucidate the structure of conscious full-body self-perception. We performed two studies in which we stroked the back of healthy individuals for three minutes while they watched the back of a distant virtual body being synchronously stroked with a virtual stick. After visuo-tactile stimulation, participants assessed changes in their bodily self-perception with a custom made self-report questionnaire. In the first study, we investigated the structure of conscious full-body self-perception by analyzing the responses to the questionnaire by means of multidimensional scaling combined with cluster analysis. In the second study, we then extended the questionnaire and validated the stability of the structure of conscious full-body self-perception found in the first study within a larger sample of individuals by performing a principle components analysis of the questionnaire responses. The results of the two studies converge in suggesting that the structure of conscious full-body self-perception consists of the following three distinct components: bodily self-identification, space-related self-perception (spatial presence), and agency.