Ashida Hiroshi, Yamagishi Noriko, Anderson Stephen J
Graduate School of Letters, Kyoto University, Kyoto 6068501, Japan.
Exp Brain Res. 2007 Dec;183(4):425-34. doi: 10.1007/s00221-007-1059-0. Epub 2007 Jul 21.
We sought to determine the extent to which colour (and luminance) signals contribute towards the visuomotor localization of targets. To do so we exploited the movement-related illusory displacement a small stationary window undergoes when it has a continuously moving carrier grating behind it. We used drifting (1.0-4.2 Hz) red/green-modulated isoluminant gratings or yellow/black luminance-modulated gratings as carriers, each curtailed in space by a stationary, two-dimensional window. After each trial, the perceived location of the window was recorded with reference to an on-screen ruler (perceptual task) or the on-screen touch of a ballistic pointing movement made without visual feedback (visuomotor task). Our results showed that the perceptual displacement measures were similar for each stimulus type and weakly dependent on stimulus drift rate. However, while the visuomotor displacement measures were similar for each stimulus type at low drift rates (<4 Hz), they were significantly larger for luminance than colour stimuli at high drift rates (>4 Hz). We show that the latter cannot be attributed to differences in perceived speed between stimulus types. We assume, therefore, that our visuomotor localization judgements were more susceptible to the (carrier) motion of luminance patterns than colour patterns. We suggest that, far from being detrimental, this susceptibility may indicate the operation of mechanisms designed to counter the temporal asynchrony between perceptual experiences and the physical changes in the environment that give rise to them. We propose that perceptual localisation is equally supported by both colour and luminance signals but that visuomotor localisation is predominantly supported by luminance signals. We discuss the neural pathways that may be involved with visuomotor localization.
我们试图确定颜色（和亮度）信号在多大程度上有助于目标的视觉运动定位。为此，我们利用了一个小的静止窗口在其后方有一个连续移动的载波光栅时所经历的与运动相关的虚幻位移。我们使用漂移（1.0 - 4.2赫兹）的红/绿调制等亮度光栅或黄/黑亮度调制光栅作为载波，每个载波在空间上都被一个静止的二维窗口截断。每次试验后，窗口的感知位置通过参考屏幕上的尺子（感知任务）或在没有视觉反馈的情况下进行的弹道指向运动的屏幕触摸（视觉运动任务）来记录。我们的结果表明，每种刺激类型的感知位移测量值相似，并且对刺激漂移率的依赖性较弱。然而，虽然在低漂移率（<4赫兹）时，每种刺激类型的视觉运动位移测量值相似，但在高漂移率（>4赫兹）时，亮度刺激的视觉运动位移测量值明显大于颜色刺激。我们表明，后者不能归因于刺激类型之间感知速度的差异。因此，我们假设我们的视觉运动定位判断对亮度模式的（载波）运动比颜色模式更敏感。我们认为，这种敏感性远非有害，可能表明旨在抵消感知体验与产生这些体验的环境物理变化之间的时间异步的机制在起作用。我们提出，感知定位同样受到颜色和亮度信号的支持，但视觉运动定位主要由亮度信号支持。我们讨论了可能与视觉运动定位有关的神经通路。
