The effect of differences in viewing environment and method on physiological responses and perceptual stability while viewing three-dimensional images

Abstract

Background Stereoscopic (3D) viewing can induce motion sickness and visual discomfort under specific environmental conditions. Light adaptation is not always linear; preceding light exposure influences subsequent physiological responses (hysteresis). However, hysteresis in 3D viewing has rarely been studied. Objective This exploratory study examined whether physiological responses exhibit hysteresis—history-dependent asymmetries between increasing and decreasing illuminance phases—under combinations of low illuminance, color temperature, and viewing mode. Methods Eight healthy adults (age 21.75 ± 0.97 yr) were exposed to stereoscopic video under eight conditions (2 color temperatures × 2 illuminance-change directions × 2 viewing modes). Illuminance was varied in stepwise fashion (10–260 lx). Electroencephalogram (EEG; Fp1/Fp2), electrocardiogram (ECG), and Stabilometry were recorded. Repeated-measures ANOVAs with Benjamini–Hochberg FDR correction and paired Hedges’ g effect sizes were computed. Results Large hysteresis effects were observed for postural sway (Hedges’ g = 0.66–1.01) and moderate effects for theta-band EEG (|g| ≈ 0.5–0.65), particularly in peripheral vision under low illuminance. Stabilometry was significantly greater at 10 lx compared to higher illuminances (p < 0.05). The interaction between illuminance and illuminance-change direction was significant for total locus length per unit area (L/A) in peripheral vision under daylight color. Conclusions Postural control, but not autonomic function, exhibited strong history dependence in response to illuminance changes during 3D viewing. Findings suggest minimum illuminance guidelines (∼80–100 lx) and consideration of illuminance-ramp rates for VR safety and 3D content design.