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Kenchi Hosokawa, Satoko Ohtsuka, Takao Sato; Depth perception from intermittent motion parallax stimuli. Journal of Vision 2005;5(8):729. doi: 10.1167/5.8.729.
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© ARVO (1962-2015); The Authors (2016-present)
Depth perception from motion parallax is based on relative motion. When object's depth changes, the change is immediately reflected in a change in relative motion as an input. However, the change is not necessarily reflected to a change in perceived depth. In this study, we examined the temporal characteristics of depth perception from motion parallax by using stimuli where relative motion was presented only a part of head movement period.
In the experiment, random-dot patterns moving with a sinusoidal velocity gradient were presented. Relative movements were presented only a part of the observers' head movement period, and stationary patterns were presented the rest of the period. Thus motion parallax changed abruptly in the middle of observers' head movement. The ratios of the moving part to the entire head movement period (motion ratios) were varied in five steps between 1/6 to 5/6. Equivalent disparities were 20, 40, and 60 min in motion period. These intermittent stimuli and those with constant parallax (constant stimuli) were presented side by side during a head movement and observers were asked to match the perceived depth of the two stimuli by adjusting parallax value of the constant stimuli to obtain the point of subjective equality(PSE) . Observers' head movement was reciprocating, and traveling 20 cm in either direction. Head movements were cued by tones so that each one-way movement takes 1 second. The results indicated that there was no noticeable change in depth during each head movement regardless of the motion ratios, and that the perceived depth was proportional averaged parallax value during a head movement. There was no effect of parallax values on this relationship. The present results suggest that depth perception induced by motion parallax is averaged over a time period which is likely to be longer than a second.
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