Visually induced motion sickness, visual stress and photosensitive epileptic seizures: what do they have in common? - preface to the special issue.

Prolonged exposure to computer animation can cause undesirable side effects (e.g., the Pokémon incident: Takahashi and Tsukahara (1998) and motion sickness with computer games: de Waard et al., 2003). In 2005, the International Organization for Standardization (ISO) published the ISO workshop agreement 3 (IWA 3) that called for more guidelines on image safety. In particular, measures to reduce incidents of visually induced motion sickness (VIMS), visual stress (VS), and photosensitive epileptic seizures (PES) were on the top of the workshop’s agenda. Subsequent to the workshop, both the ISO and the Commission Internationale de ĺEclairage (CIE) have commissioned two technical study groups to draft guidelines concerning the quantification and prevention of VIMS, VS, and PES (ISO/TC159/SC4/SGISO and CIE TC-167: Ujike, 2007). Among the three disorderly conditions, PES is most clearly defined. A PES is an abnormal brain activity triggered by viewing certain visual stimuli. Its symptoms are clearly measurable by EEG recordings and about 1 in 4000 persons in the United Kingdom are susceptible (Harding and Harding, 2007). The type of visual stimuli that will cause PES has been the subject of many studies (see Harding’s article in this special issue) and its understanding has led to the development of an ITC guideline (ITC, 2001). Despite decades of research, VIMS (also known as cinema sickness: Griffin, 1990; cybersickness: McCauley and Sharkey, 1992; vection induced MS: Hettinger et al., 1990; and simulator sickness: Kennedy et al., 1990), the etiology of VIMS is still unknown. It is a condition in which viewers experience symptoms of nausea and eye fatigue during or after viewing visual stimuli with compelling ego-motion inappropriate to their physical body motion (Reason, 1978). Hettinger et al. (1990) reported correlations between levels of vection (illusion of self-motion) and levels of VIMS. They predicted that the VIMS is induced by sensations of vection (illusion of self-motion). Stoffregen and Smart (1998) further predicted that the illusion of self-motion causes postural instability and VIMS is a disorderly condition associated with prolonged postural instability. Stoffregen and his colleagues found that VIMS is preceded by postural instability. Similar to this line of thoughts, Bos and Bles (1998) predicted that VIMS is caused by a kind of disorientation in which ego-motion stimuli promote a subjective sense of vertical axis that is different from the vertical axis aligned with the gravitation force. Bos and Bles (1998) reported that VIMS commonly induced by watching a rotating drum could be eliminated by aligning the drum and