Krukowski Anton E, Pirog Kathleen A, Beutter Brent R, Brooks Kevin R, Stone Leland S
Human Factors Research and Technology Division, NASA Ames Research Center, Moffett Field, CA, USA.
J Vis. 2003 Dec 17;3(11):831-40. doi: 10.1167/3.11.16.
It has long been known that ocular pursuit of a moving target has a major influence on its perceived speed (Aubert, 1886; Fleischl, 1882). However, little is known about the effect of smooth pursuit on the perception of target direction. Here we compare the precision of human visual-direction judgments under two oculomotor conditions (pursuit vs. fixation). We also examine the impact of stimulus duration (200 ms vs. ~800 ms) and absolute direction (cardinal vs. oblique). Our main finding is that direction discrimination thresholds in the fixation and pursuit conditions are indistinguishable. Furthermore, the two oculomotor conditions showed oblique effects of similar magnitudes. These data suggest that the neural direction signals supporting perception are the same with or without pursuit, despite remarkably different retinal stimulation. During fixation, the stimulus information is restricted to large, purely peripheral retinal motion, while during steady-state pursuit, the stimulus information consists of small, unreliable foveal retinal motion and a large efference-copy signal. A parsimonious explanation of our findings is that the signal limiting the precision of direction judgments is a neural estimate of target motion in head-centered (or world-centered) coordinates (i.e., a combined retinal and eye motion signal) as found in the medial superior temporal area (MST), and not simply an estimate of retinal motion as found in the middle temporal area (MT).
长期以来，人们一直知道眼睛对移动目标的追踪对其感知速度有重大影响（奥伯特，1886年；弗莱施尔，1882年）。然而，关于平稳追踪对目标方向感知的影响却知之甚少。在此，我们比较了两种眼动条件（追踪与注视）下人类视觉方向判断的精度。我们还研究了刺激持续时间（200毫秒与约800毫秒）和绝对方向（基本方向与倾斜方向）的影响。我们的主要发现是，注视和追踪条件下的方向辨别阈值没有差异。此外，两种眼动条件显示出相似大小的倾斜效应。这些数据表明，无论有无追踪，支持感知的神经方向信号都是相同的，尽管视网膜刺激明显不同。在注视期间，刺激信息仅限于大的、纯粹的周边视网膜运动，而在稳态追踪期间，刺激信息由小的、不可靠的中央凹视网膜运动和一个大的传出副本信号组成。对我们研究结果的一个简洁解释是，限制方向判断精度的信号是在颞上内侧区（MST）发现的以头部为中心（或以世界为中心）坐标的目标运动的神经估计（即视网膜和眼球运动的组合信号），而不仅仅是在颞中区（MT）发现的视网膜运动估计。
