Bodily self-consciousness varies across the menstrual cycle

Aims: Physiological signals coming from both external and internal senses contribute to bodily self-consciousness, the basic feeling that one has a body (body ownership) that acts according to one’s will (body agency) and occupies a specific position (body location). The perception of internal signals (interoception) seems to differ between males and females, and, importantly for the present study, bodily representation changes in females according to their menstrual cycle. However, very little is known about how women integrate interoceptive and exteroceptive bodily cues and the menstrual phase in their conscious experience of the body. To fill this gap, we induced a breath-based bodily illusion (‘embreathment illusion’) that we recently described in a sample of male individuals and tested if the phase of the menstrual cycle influences the strength of the illusion in a sample of healthy young females. Materials and Methods: 15 healthy females took part in the study (age: mean ± SD = 24.67 ± 4.03 years). Participants underwent an immersive virtual reality (IVR) experience consisting of eight counterbalanced experimental conditions, combining two different avatar looks (i.e. ‘human-like’ vs. ‘wooden’ avatar) with two different points of view (i.e. first-person vs. third-person perspective) and two different breathing patterns (same vs. opposite breathing pattern as the participant). At the end of each scenario, participants answered a 5-item questionnaire on feelings of body ownership, agency, and location using a 0 to 100 visual analogue scale (VAS). Afterwards, measures of interoceptive accuracy (i.e. performance in the heartbeat counting task and pneumoception task) and sensibility (i.e. scores on the MAIA questionnaire) were collected. Results: Preliminary results showed a statistically significant main effect of feelings of bodily self-consciousness on VAS response (F=52.27; p<0.001). This main effect was qualified by an interaction between feelings of bodily self-consciousness and participants’ menstrual phase (F=2.77; p<0.05). In particular, post-hoc contrasts revealed that women in the premenstrual phase felt they controlled the avatar's movements more than participants in the menstrual phase (p<0.01). Discussion and Conclusions: The results of the experiment suggest that women do adjust their corporeal awareness to menstrual signals, with potential implications for the study of disordered bodily self-consciousness in female clinical populations (eating disorders, schizophrenia).