VR IN EATING DISORDERS: THE RATIONALE Virtual environments (VEs) has recently attracted much attention in clinical medicine. Given the new opportunities offered by this new technology, some ongoing research project are now testing the possibility of using VR for behavioural therapy. Since the spring of 1993, researchers at Georgia Institute of Technology's Graphics, Visualization, and Usability Center have been exploring the possibility of using virtual environments for therapy of individuals with psychological disorders (Hodges, Bolter, Mynatt, Ribarsky, & Van Teylingen, 1993; Rothbaum et al., 1995a, 1995b). Hodges et al. (1995) report on a project that makes use of VEs to provide acrophobic patients with fear-producing experiences of heights in a safe situation. In a more recent work Hodges, Rothbaum, Watson, Kessler & Opdyke (1996) verified the possibility of using a virtual reality airplane for exposure therapy in the treatment of fear of flying. Kijima, Shirakawa, Hirose, & Nihei (1994) have been exploring the use of VEs to reproduce sand box play, a technique used in diagnosis and psychotherapy. Strikland (1996), developed a VR application to help autistic children. The idea is to use VR to provide a customized learning environment for individual with autism. One of the main advantages of a virtual environment is that it can be used in a medical facility, thus avoiding the need to venture into public situations. Infact, in these studies VEs are mainly used in order to simulate the real world and to assure the researcher full control of all the parameters implied. However a promising new use of VEs based on a totally different approach is modification of body representations. Here is described the rationale of such approach.

In contrast to the great number of publications on body image, only a few papers focus on the treatment of a disturbed body image in eating disorders. In general, two direct and specific approaches can be distinguished: a cognitive/behavioural approach aimed at influencing patients' feelings of dissatisfaction with different parts of their bodies by means of individual interviews, relaxation and imaginal techniques (Butter & Cash, 1987), and a visual/motorial approach which makes use of videorecordings of particular gestures and movements with the aim of influencing the level of bodily awareness (Wooley & Wooley, 1985). An interesting possibility could be the integration of the two methods (cognitive-behavioural and visual-motorial) commonly used in the treatment of body experience disturbances within a virtual environment. A choice of this type would make it possible to use the psycho-physiological effects provoked by the experience for therapeutical purposes. It is well known that in practically all VR systems, the human operator's normal sensorimotor loops are altered by the presence of distorsions, time delays and noise in the system. The somesthetic systems has a proprioceptive subsystem that senses the body's internal state, such the position of limbs and joints and the tension of the muscles and tendons. Mismatches between the signals from the proprioceptive system and the external signals of a virtual environments alter body perceptions and can cause discomfort or simulator sickness (Sadowsky & Massof, 1994). In a recent study, Cioffi (1993) analysed these effects and found that, in VR, the self-perception of one's own body undergoes profound changes that are similar to those achieved in the 1960s by many psychologists in their studies of perceptual distorsion. In particular, about 40% of the subjects felt as if they had "dematerialised" or as if they were in the absence of gravity; 44% of the men and 60% of the women claimed not to feel their bodies. Perceptual distorsions, leading to a few seconds of instability and a mild sense of confusion, were also observed in the period immediately following the virtual experience. Such effects, attributable to the reorganisational and reconstructive mechanisms necessary to adapt the subjects to the qualitatively distorted world of VR, could be of great help during the course of a therapy aimed at influencing the way the body is experienced, because they lead to a greater awareness of the perceptual and sensory/motorial processes associated with them. When a particular event or stimulus violates the information present in the body schema (as occurs during a virtual experience), the information itself becomes accessible at a conscious level (Baars, 1988). This facilitates the process of modification and, by means of the mediation of the self (which tries to integrate and maintain the consistency of the different representations of the body), also makes it possible to influence the body image.