VISUAL ACCOMMODATION AND SUBJECT PERFORMANCE DURING A STEREOGRAPHIC OBJECT TASK USING LIQUID-CRYSTAL SHUTTERS

Virtual reality has become popular in a variety of fields. Three exper iments to study visual accommodation and task performance during stere ographic vision were carried out in order to better understand the hum an response to virtual reality. Visual accommodation to stereograms on CRT was studied. Subjects could see the target on the CRT display bin ocularly through liquid crystal shutters. Accommodation to a stereogra m with step changes in distance was tested first. As the second experi ment, accommodation to a stereogram with gradual changes in distance, and comparison of ability to perform a colour photograph stereogram ta sk were tested. Finally, accommodation and subject performance during a prolonged stereographic object task were observed for 30 min. A virt ual 'gate' was formed at a position 1.2 m from the subject. The virtua l target moved forward and backward through this gate between the posi tions of 0.8 m and 2.0 m. The subjects were asked to focus on the targ et and press a button as it moved through the virtual gate. Subjective response to the task and the error between the position where the but ton was pressed and the gate was recorded, It was concluded that there are some people who exhibit large changes in accommodation while perf orming a stereographic task. There is a tendency to accommodate to a d istance nearer than the baseline. Prolonged stereoscopic viewing cause d visual fatigue or loss of accommodation and diminished task performa nce.