Clinical Correlates of Unidimensional and Multidimensional Full-Body Illusion in Female Adolescents with Anorexia Nervosa

Virtual reality (VR)-based mirror exposure therapies (VR-MET) are widely used for the treatment of anorexia nervosa (AN). However, their effectiveness may depend on how much patients perceive a virtual body as their own, a phenomenon known as the full-body illusion (FBI). This study examined FBI levels and their clinical correlates in adolescents with AN, a key developmental period in the disorder. Forty-nine female adolescents with AN were immersed in a VR environment and embodied in avatars reflecting their own body shape and weight through visuomotor and visuo-tactile stimulation. The FBI was assessed using both unidimensional measures and a multidimensional embodiment questionnaire. Correlation analyses and multiple linear regressions were conducted to explore associations between FBI components and AN-related variables, including body mass index, body dissatisfaction, body anxiety, state anxiety, and fear of gaining weight (FGW). Results showed significant negative correlations between body anxiety and FGW and FBI, particularly its unidimensional and ownership components, with FGW explaining 28.1 percent of FBI variance. Consistent with the Allocentric Lock hypothesis, these findings suggest that adolescents with AN may rely more strongly on stored, distorted body representations than on immediate multisensory evidence (sight, touch, and proprioception), creating a cognitive barrier to virtual ownership and potentially limiting VR-MET effectiveness during adolescence. Future research should incorporate more diverse samples—including different ages and genders—to further clarify the clinical role of embodiment processes in VR-based interventions.