Faculty of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan.
Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan.
J Neurophysiol. 2022 Apr 1;127(4):1198-1207. doi: 10.1152/jn.00498.2021. Epub 2022 Mar 30.
Expectations about forthcoming visual motion shaped by observers' experiences are known to induce anticipatory smooth eye movements (ASEMs) and changes in visual perception. Previous studies have demonstrated discrete effects of expectations on the control of ASEM and perception. However, the tasks designed in those studies were not able to segregate the effects of expectations and execution of ASEM itself on perception. In the present study, we attempted to directly examine the effect of ASEM itself on visual speed perception with a two-alternative forced-choice (2AFC) task, in which observers were asked to track a pair of sequentially presented visual motion stimuli with their eyes and to judge whether the second stimulus (test stimulus) was faster or slower than the first (reference stimulus). Our results showed that observers' visual speed perception, quantified by a psychometric function, shifted according to ASEM velocity. This was the case even though there was no difference in the steady-state eye velocity. Further analyses revealed that the observers' perceptual decisions could be explained by a difference in the magnitude of retinal slip velocity in the initial phase of ocular tracking when the reference and test stimuli were presented, rather than in the steady-state phase. Our results provide psychophysical evidence of the importance of initial ocular tracking in visual speed perception and the strong impact of ASEM. We provide psychophysical evidence that the execution of anticipatory smooth eye movement (ASEM) leads to underestimation of visual speed perception, that is, observers perceive the object motion velocity as slower than when ASEM is not induced, even though the performance of subsequent ocular tracking is comparable. Moreover, our results showed that such perceptual decisions regarding object motion velocity were derived from the ASEM-induced decrease in retinal slip velocity during the initial phase of ocular tracking.
人们已经知道，对即将到来的视觉运动的预期会引起预期的平滑眼动（ASEM）和视觉感知的变化。先前的研究已经证明了期望对 ASEM 控制和感知的离散影响。然而，这些研究中的任务设计无法将期望的影响和 ASEM 本身的执行对感知的影响分开。在本研究中，我们试图通过一个二选一强制选择（2AFC）任务直接检查 ASEM 本身对视觉速度感知的影响，在该任务中，观察者被要求用眼睛跟踪一对连续呈现的视觉运动刺激，并判断第二个刺激（测试刺激）是否比第一个刺激（参考刺激）快或慢。我们的结果表明，观察者的视觉速度感知，通过心理物理函数来量化，根据 ASEM 的速度而发生变化。即使在稳态眼速没有差异的情况下也是如此。进一步的分析表明，观察者的感知决策可以用参考和测试刺激呈现时眼球跟踪初始阶段视网膜滑移速度的差异来解释，而不是在稳态阶段。我们的结果提供了心理物理学证据，证明了初始眼球跟踪在视觉速度感知中的重要性和 ASEM 的强烈影响。我们提供了心理物理学证据，表明预期平滑眼动（ASEM）的执行会导致视觉速度感知的低估，即观察者感知到的物体运动速度比不诱导 ASEM 时更慢，尽管后续眼球跟踪的性能相当。此外，我们的结果表明，关于物体运动速度的这种感知决策是源自于在眼球跟踪的初始阶段 ASEM 引起的视网膜滑移速度的降低。
