Geesaman B J, Qian N
Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge 02139, USA.
Vision Res. 1996 Oct;36(20):3281-92. doi: 10.1016/0042-6989(96)00054-5.
Using random dot stimuli well controlled for dot speed, we found that the moving features in expanding patterns appear to move faster than those in rotating patterns. The illusion is well correlated with the strength of the global motion signal. For example, in displays where the number of motion directions defining the patterns is reduced, the magnitude of the illusion decreases. Similarly, the strength of the effect diminishes as dot density is reduced. In patterns where only wedge-shaped segments of the stimuli are left exposed, the difference in perceived speed increases with the angular size of the wedge. Stimulus placement relative to the fixation point has little effect on the persistence of this phenomenon-expansion patterns appear to contain elements of greater speed, independent of stimulus eccentricity. These results argue against a local explanation for this perceptual illusion, suggesting that the global motion pattern of the stimulus, per se, is responsible.
使用对点速度控制良好的随机点刺激，我们发现膨胀模式中的运动特征似乎比旋转模式中的运动特征移动得更快。这种错觉与全局运动信号的强度密切相关。例如，在定义模式的运动方向数量减少的显示中，错觉的程度会降低。同样，随着点密度的降低，这种效应的强度也会减弱。在仅留下刺激的楔形部分暴露的模式中，感知速度的差异随着楔形的角度大小而增加。刺激相对于注视点的位置对这种现象的持续性影响很小——膨胀模式似乎包含速度更快的元素，与刺激离心率无关。这些结果反对对这种感知错觉的局部解释，表明刺激本身的全局运动模式是原因所在。
