Bioresponse to Stereoscopic Movies Presented via a Head-mounted Display

Three-dimensional (3-D) television sets are already available in the market and are becoming increasingly popular among consumers. The 3-D movies they play, however, induce the negative sensations of asthenopia and motion sickness in some viewers. Visually induced motion sickness (VIMS) is caused by sensory conflict, i.e., a disagreement between vergence and visual accommodation during the viewing of stereoscopic images. VIMS can be analyzed both subjectively and physiologically. The objective of this study is to develop a method for detecting VIMS. We quantitatively measured head acceleration and body sway during viewer exposure to both a twodimensional (2-D) image and a conventional three-dimensional (3-D) movie. The subjects wore headmounted displays (HMDs) and maintained the Romberg posture for the first 60 s and a wide stance (midlines of the heels 20 cm apart) for the next 60 s. Head acceleration was measured using an active tracer at a sampling frequency of 50 Hz. Subjects completed the Simulator Sickness Questionnaire (SSQ) immediately afterwards. Statistical analysis was then applied to the SSQ subscores and to each index of stabilograms. Transfer function analysis indicated that the acceleration of the head in the anteriorposterior direction while watching a 3-D movie can affect lateral body sway, thereby causing VIMS.