A PRELIMINARY STUDY Until now some problems have existed with virtual reality. There are anecdotal reports that immersive VR can lead to symptoms similar to motion sickness symptoms. Visually induced motion sickness is a syndrome that occasionally occurs when physically stationary individuals view compelling visual representations of self motion. It may also occur when detectable lags are present between head movements and recomputations and presentation of the visual display in HMD. Motion sickness is characterised by a diverse set of symptoms but is primarily exemplified by nausea and vomiting. In the case of VEBIM, with adults and adolescents as possible subjects, both including people with psychological and physical problems, the need to verify the problems associated with operating in a virtual environment has to be addressed. The present preliminary study was designed to test VEBIM effects on a non-clinical sample. In particular the study was designed to: (1) verify the effects provoked by VEBIM on blood pressure and heart rate; (2) verify the effects provoked by VEBIM on the body experience. Subjects 71 subjects (47 males and 24 females: mean age: 23.18+/-7.54; mean weight: 67.34 Kg +/- 15.42; mean height 173.3 cm +/- 7.97) attending a conference on virtual reality participated in the study.   Procedures All the subjects were submitted to VEBIM for no more than ten minutes and no less than eight. All the subjects included in the study reached zone 5. No subject experienced zone 6.   Guided Imagery approach After the subject entered in a zone the therapist described the situation and encouraged him/her to associate to it in pictures rather than in words, and to give a detailed description of them following the procedure described by Leuner (1969) and Kearney-Cooke (1989). This procedure was repeated for each of the five zone experienced.

Measures

Before the virtual experience the subjects were fitted with a blood pressure cuff and were asked to sit quietly during a 5-minute baseline period and to relax. During this period blood pressure and heart rate were recorded. Just after the virtual experience and after a 10-minute post-task period blood pressure and heart rate were recorded again.

Just before entering the virtual environment and just after, all the subjects were submitted to two scales for assessing body experience:

- the Figure Rating Scale - FRS (Thompson & Altabe, 1991), a set of 9 male and female figures which vary in size from underweight to overweight.

- the Contour Drawing Rating Scale - CDRS (Thompson & Gray, 1995) a set of 9 male and female figures with precisely graduated increments between adiacent sizes.

- the Breast/Chest Rating Scale - BCRS (Thompson & Tantleff, 1992), a set of 5 male and 5 female schematic figures, ranging from small to large upper torso.

In these tests subjects are asked to rate the figures based on the following instructional protocol: (a) current size and (b) ideal size. The difference between the ratings is called the "discrepancy index" and is considered to represent the individual's level of dissatisfaction. Both scales have good test-retest reliability.

Statistical Analysis

A power calculation was made to verify the opportunity to obtain statistically significant differences between the pre and post-VR scores. Given the low statistical power we decided to use exact methods, a series of statistical algorithms developed by the Harvard School of Public Health, that enable researchers to make reliable inferences when data are small, sparse, heavily tied or unbalanced (SPSS, 1995). The exact method used to compare the scores was the marginal homegeneity test (Agresti, 1990).

Results

Table 1 lists the means and standard deviations for the pressure and heart rate scores, across the three measurement occasions. No significant difference was found before and after the VR experience. Only two of the subject experienced simulation sickness.

	Measurement 1		Measurement 2		Measurement 3
	Mean	SD	Mean	SD	Mean	SD
Systolic Pressure	134.61	20.06	133.09	20.8	124.13	18.56
Diastolic Pressure	89.23	21.09	88.2	23.72	84.6	16.38
Heart rate	74.01	15.68	72.11	11.06	72.09	14.14

Table 1. Means and standard deviations for the pressure and heart rate scores

Table 2 presents the means and standard deviations for the body image scores obtained before and after the virtual experience. The marginal homogeneity test reported significant differences in the Ideal FRS and Ideal CDRS scores: both scores were higher after experiencing VEBIM. An analysys of the three discrepancy indexes revealed significant lower values for FRS and CDRS after the experience in the virtual environment. These results mean that VEBIM is able to reduce the body dissatisfaction of the subjects.

All the subjects	Real FRS	Ideal FRS	Real CDRS	Ideal CDRS	Real BCRS	Ideal BCRS
Before	3.8+/-1.34	3.18+/-0.72***	4.79+/-1.49	4.11+/-0.95*	2.79+/-1.30	2.91+/-1.95
After	3.84+/-1.28	3.53+/-0.96***	4.74+/-1.53	4.21+/-1.07*	2.82+/-1.27	2.94+/-0.97

* p<0.05 ** p<0.01 *** p<0.005

Table 2. Means and standard deviations for the body image scores

To explore for possible sex differences on each body image variable, we divided the sample in two groups according to the gender and resubmitted them to the marginal homegeneity test. Means and standard deviations for the body image scores are reported in Table 3 (female subjects) and Table 4 (male subjects).

Males	Real FRS	Ideal FRS	Real CDRS	Ideal CDRS	Real BCRS	Ideal BCRS
Before	4.12+/-1.42	3.8+/-0.82	5.19+/-1.48*	4.87+/-1.06**	2.67+/-1.19	3+/-0.93
After	4.09+/-1.41	3.89+/-0.89	5.02+/-1.6*	4.62+/-0.85**	2.76+/-1.23	3.2+/-0.82

* p<0.05 ** p<0.01 *** p<0.005

Table 3 Means and standard deviations for the body image scores in males

Females	Real FRS	Ideal FRS	Real CDRS	Ideal CDRS	Real BCRS	Ideal BCRS
Before	3.14+/-0.93	2.61+/-0.8***	4+/-1.18	3.5+/-0.83	2.98+/-1.49	2.75+/-1.13
After	3.35+/-0.81	2.91+/-0.75***	4.21+/-1.25	3.52+/-1.08	2.93+/-1.35	2.52+/-1.08

* p<0.05 ** p<0.01 *** p<0.005

Table 4 Means and standard deviations for the body image scores in females

In the male sample significant differences were found in the Real CDRS and Ideal CDRS scores: both scores were lower after the virtual experience. No significant differences were found in the discrepancy index.

For the female sample the marginal homogeneity test reported a significant difference in the Ideal FRS score: the scores was higher after experiencing VEBIM. An analysys of the discrepancy indexes showed a significant lower value for FRS after the virtual experience.

Conclusions

The present study shows that even a short-term application of VEBIM is able to partially reduce the level of body dissatisfaction without any major side effect. The fact that the at least the female subjects of our sample view their body as nearer after the procedure than before to their ideal means that the virtual environment has induced a more realistic view of their body.

As such, the procedure might be helpful as a part of a comprehensive treatment package to break through the "resistance" to treatment in clinical subjects (Vandereycken, 1990; Vandereycken, Probst, & Meermann, 1988) . Nevertheless, an alteration of the body image toward a more realistic "proportion"- that is, closing the gap between the actual and ideal body image - might be decisive for the long-term outcome. We assume that the virtual experience might be useful to achieve these goal, not as a magic trick but as a catalyzer in a therapeutic process.

Of course we have to test both the effects of the virtual environment on a clinical sample and how long the impact of the virtual environment will last. In this preliminary study we have limited the test to just one session, but from a therapeutic viewpoint it seems more reasonable to repeat the procedure. We have already planned an extention of the study as a part of the VREPAR research project.