Integration time for the perception of depth from motion parallax

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• 作者：Mark Nawrot^a ; ^{mark.nawrot@ndsu.edu} ; Keith Stroyan^b
• 关键词：Depth perception ; Motion parallax ; Pursuit eye movements ; Binocular stereopsis ; Motion masking
• 刊名：Vision Research
• 出版年：2012
• 期刊代码：268_00426989
• 类别：med
• 出版时间：15 April, 2012
• 卷：59
• 期：Complete
• 页码：64-71
• 文件大小：375 K

摘要

The perception of depth from relative motion is believed to be a slow process that 鈥渂uilds-up鈥?over a period of observation. However, in the case of motion parallax, the potential accuracy of the depth estimate suffers as the observer translates during the viewing period. Our recent quantitative model for the perception of depth from motion parallax proposes that relative object depth (d) can be determined from retinal image motion (d胃/dt), pursuit eye movement (d伪/dt), and fixation distance (f) by the formula: d/f 鈮?#xA0;d胃/d伪. Given the model鈥檚 dynamics, it is important to know the integration time required by the visual system to recover d伪 and d胃, and then estimate d. Knowing the minimum integration time reveals the incumbent error in this process. A depth-phase discrimination task was used to determine the time necessary to perceive depth-sign from motion parallax. Observers remained stationary and viewed a briefly translating random-dot motion parallax stimulus. Stimulus duration varied between trials. Fixation on the translating stimulus was monitored and enforced with an eye-tracker. The study found that relative depth discrimination can be performed with presentations as brief as 16.6 ms, with only two stimulus frames providing both retinal image motion and the stimulus window motion for pursuit (mean range = 16.6-33.2 ms). This was found for conditions in which, prior to stimulus presentation, the eye was engaged in ongoing pursuit or the eye was stationary. A large high-contrast masking stimulus disrupted depth-discrimination for stimulus presentations less than 70-75 ms in both pursuit and stationary conditions. This interval might be linked to ocular-following response eye-movement latencies. We conclude that neural mechanisms serving depth from motion parallax generate a depth estimate much more quickly than previously believed. We propose that additional sluggishness might be due to the visual system鈥檚 attempt to determine the maximum d胃/d伪 ratio for a selection of points on a complicated stimulus.