Holcombe A O, Intriligator J, Tse P U
Department of Psychology, Harvard University, 33 Kirkland St., Cambridge, MA 02138, USA.
Percept Psychophys. 2000 Nov;62(8):1619-24. doi: 10.3758/bf03212159.
When a bright white disk revolves around a fixation point on a gray background, observers perceive a "spoke": a dark gray region that connects the disk with the fixation point. Our first experiment suggests that motion across the retina is both necessary and sufficient for spokes: The illusion occurs when a disk moves across the retina even though it is perceived to be stationary, but the illusion does not occur when the disk appears to move while remaining stationary on the retina. A second experiment shows that the strength of the illusion decreases with decreasing luminance contrast until subjective equiluminance, where little or no spoke is perceived. These results suggest that spokes originate at an early, predominantly luminance-based stage of motion processing, before the visual system discounts retinal motion caused by smooth pursuit.
当一个明亮的白色圆盘在灰色背景上围绕一个固定点旋转时，观察者会感知到一条“辐条”：一个将圆盘与固定点连接起来的深灰色区域。我们的第一个实验表明，视网膜上的运动对于辐条的形成既是必要的也是充分的：即使圆盘被感知为静止，但当它在视网膜上移动时，错觉就会出现；而当圆盘看似移动但在视网膜上保持静止时，则不会出现错觉。第二个实验表明，随着亮度对比度的降低，错觉的强度会减弱，直到主观等亮度时，几乎感觉不到或根本感觉不到辐条。这些结果表明，辐条起源于运动处理的早期阶段，主要基于亮度，在视觉系统消除由平稳追踪引起的视网膜运动之前。
