Evaluating sense of embodiment in virtual reality with EEG: A scoping review

In Virtual Reality (VR) experiences, embodiment refers to owning and controlling a virtual body. It combines Sense of Body Ownership, Sense of Agency, and Sense of Self Location, making the users feel that the virtual body is their own. Despite the growing interest in the topic, embodiment still lacks quantitative objective and subjective standard practices for its assessment. In this context, we performed a scoping review searching scientific databases to assess the extent of existing literature on the topic of embodiment, its components, and their assessment via electroencephalography (EEG)-based techniques. We also investigated the relationship between physiological EEG-derived indices and psychometric data collected through questionnaires aimed at evaluating the participants' subjective experience. Forty-one articles were included in the review and classified according to the embodiment modulated component(s) and EEG techniques. The results of the literature analysis highlighted high heterogeneity in the VR-induced stimulations and in EEG data collection, preprocessing, and analysis. Also, in the reviewed studies, subjective feedback was typically collected via non-standardized and often non-validated questionnaires. Such marked heterogeneity reflects a lack of consensus on key subjective and EEG-based markers of embodiment, suggesting the need for greater standardization in the design of future research. Nonetheless, individual studies’ results indicate that embodiment can elicit measurable responses that can be quantified via EEG-derived metrics and correlated with subjective feelings. Further investigations are thus needed to better design VR experiences involving embodiment.