A new study has determined why prolonged viewing of stereo 3-D displays on smartphones and desktop devices can lead to visual discomfort, fatigue and headaches. Researchers say these displays strain our eyes by forcing us to focus on the screens and simultaneously adjust to the distance of the content.
This conflict and its effect on viewers of stereo 3-D is referred to as "vergence-accommodation," according to a new Journal of Vision study.
"When watching stereo 3-D displays, the eyes must focus — that is, accommodate — to the distance of the screen because that's where the light comes from. At the same time, the eyes must converge to the distance of the stereo content, which may be in front of or behind the screen," explained Martin Banks, professor of optometry and vision science, University of California, Berkeley.
Through a series of experiments on adults, Banks and his team observed the interaction between the viewing distance and the direction of the conflict, and examined whether placing the content in front of or behind the screen affected viewer discomfort.
The results found that on devices such mobile phones and desktop displays that are typically viewed a short distance away, stereo content placed in front of the screen — appearing closer to the viewer and into the space of viewer's room — was less comfortable than content placed behind the screen.
Conversely, when viewing at a longer distance such as a movie theater screen and stereo content placed behind the screen — appearing as though the viewer is looking through a window scene behind the screen — was also less comfortable.
Discomfort associated with viewing stereo 3-D is a major problem that may limit the use of technology," Banks said. "We hope that our findings will inspire more research in this area."
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