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What is the source of discomfort in 3D viewing: Accomodation, convergence, or immersion?

6 June 2012


About 15 to 20% of viewers experience increased discomfort after sustained viewing of stereoscopic 3D (S3D) movies. These symptoms unique to S3D viewing include visual (double vision, blurred vision) and motion sickness symptoms; little is understood about their underlying causes.

Based on our previous findings, here symptoms in S3D viewing are categorized as visual, ocular, motion sickness, physical, and cognitive. Reported evidence shows that all five types of symptom were heightened as the amount of image disparity (lateral spatial separation of corresponding images) was increased, indicating an underlying cause associated with image disparity. In addition, viewer’s perceived immersion increased with greater image disparity, until a critical level was achieved beyond which both perceived immersion and viewing symptoms decreased.

One of the likely underlying mechanisms for heightened viewing symptoms is the trigeminal-vascular reflex (TVR). The TVR can be triggered by light simulation (e.g., glare or flickering), motion stimulation, and excessive pressure on ophthalmic muscles (iris, ciliary body, and eye muscle). The TVR in turn disrupts cortical/subcortical activity in the anterior cingulate (attention and awareness), prefrontal (decision making and memory), and amygdala (emotion). This hypothesis would account for the increase of all five hype of symptoms in S3D viewing.

We discussed the likely conditions that heighten viewing symptoms in S3D viewing, including enhanced visually-based depth and motion perception, strong light stimulation and flickering images in a dark viewing condition, pressure stress from wearing 3D glasses, and the exceeding accommodative/convergence stress associated with S3D viewing. Our recent findings showed that one or more such conditions were associated with the abovementioned symptoms in both 2D and 3D viewing (e.g., sustained reading with high glare).

Effective changes for attenuating S3D viewing symptom were discussed. These changes include lowering image disparity, developing standards for viewing environment, creating ergonomic 3D glasses, and selectively reducing visual cues inducing perceived motion in depth.


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