Peter A. Howarth and Kevin J. Hill
Visual Ergonomics Research Group1
Department of Human Sciences, Loughborough University,
Leicestershire, LE11 3TU, England.
The increasing use of Head-Mounted Displays (HMDs) for the viewing of virtual environments has been accompanied by a heightened awareness that, for some people, immersion in this way produces symptoms akin to those of motion sickness. However, this 'virtual simulation sickness', or 'cybersickness', must have a different genesis from that of motion sickness, as closing the eyes prevents the former but not the latter. Although it is known that most people can adapt (or 'habituate' if the stimulus is one that is repeated) to real motion ( Griffin, 1990), the characteristics of habituation to the appearance of motion are not yet known.
In order to examine this habituation, we extended the work of Ramsey ( 1996) by examining two groups of participants who had different amounts of visual stimulation ( Hill and Howarth, 1999). Of the 26 participants who started that experiment, 19 completed the full five days, during which time they were exposed to a virtual environment for twenty minutes (unless their symptoms became too severe) on a daily basis. Eleven of these participants were also exposed for an extra fifteen minutes daily, to provide additional visual stimulation. All 19 participants showed habituation over the week, with those who had been given the extra exposure showing the greater effect. We have now re-examined 10 of these participants (those available) after a time lapse of six months. During this time none of the participants experienced any immersion in a virtual environment, and we report here that the level of habituation previously seen has not been maintained.____________________