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Jacqueline L. Snyder, Jeffrey B. Mulligan, Laurence T. Maloney; Horizontal binocular disparity facilitates visual search in stereoscopically-viewed displays. Journal of Vision 2004;4(8):679. doi: https://doi.org/10.1167/4.8.679.
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© ARVO (1962-2015); The Authors (2016-present)
In stereoscopically-viewed displays, search for a target among distractors is facilitated when the target and distractors lie in a planar array (He & Nakayama, PNAS, 1995, 92, 11155–59). We investigated observers' ability to detect a target within a planar array of distractors, while simultaneously viewing planar “distractor arrays” at other horizontal binocular disparities. We varied the disparity of these arrays to optimize search performance and to minimize the disparity required to segment the target's array from the distractor arrays. Stimuli consisted of three 3-by-4 arrays of red and green rectangles arranged on a black background (after He & Nakayama). Stimulus presentation time was 750ms. The arrays (denoted NEAR, CENTER and FAR) were ordered in depth along the line of sight. The disparity difference, D, was always equal between the NEAR and CENTER arrays, and CENTER and FAR arrays. The arrays were interleaved vertically so that the rectangles did not occlude each other. The 1st, 4th and 7th rows belonged to the NEAR array; the 2nd, 5th, and 8th to the CENTER array; and the 3rd, 6th and 9th to the FAR array. D ranged from 0–30 arc minutes of visual angle across trials. Two observers judged if a color singleton target was present in the CENTER array (yes/no task). Each rectangle in the NEAR and FAR arrays was randomly set to red or green. When D=0, the observer perceived all three arrays at the same depth, and her task was to detect the color singleton within the 2nd, 5th and 8th rows of the display. We measured disparity tuning curves as percent correct versus D. Without a disparity difference between the planes, both observers performed at chance. Increasing D to 15 arc min was sufficient to increase search performance to 95% correct for both observers, and performance was not improved by further increases in D. These results demonstrate that observers can use small disparity differences to restrict and guide search in stereoscopically-viewed displays.
NIH Grant EY08266; HFSP Grant RG0109/1999-B; NASA GSRP Dissertation Fellowship; NASA AOS Project of NASA Airspace Systems.
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