Measurement of postural stability before and after immersion in a virtual environment.

Research into the effects of simulators has led to suggestions that postural instability occurring after immersion in a virtual reality virtual environment (VR/VE) may have direct implications for the safety of post-immersion activities such as driving or operating machinery. However, experimental studies have highlighted a lack of standardisation in the postural stability measurement techniques applied and subsequent inconsistencies in the results obtained. An experiment was conducted to evaluate the use of static, dynamic and posturographic postural stability measures in determining the effect of participation in an interactive virtual environment (VE) for 20 min. The results demonstrate differences in the sensitivity of postural stability measurement techniques and variations in inter- and intra-individual responses to measures. The VE immersion was found to produce postural instability only when measured using a posturographic technique under normal stance static posture, and then only mildly and not long-lasting. No associations were found between reported symptoms of simulator sickness and postural stability with postural stability measures. This paper discusses issues relating to postural stability measurement and the implications for evaluation of virtual environment effects.