Snowden R J
School of Psychology Cardiff University Cardiff CF1 9EB Wales UK.
Curr Biol. 1998 Dec 3;8(24):1343-5. doi: 10.1016/s0960-9822(07)00567-2.
Where do we perceive an object to be when it is moving? Nijhawan [1] has reported that if a stationary test pattern is briefly flashed in spatial alignment with a moving one, the moving element actually appears displaced in the direction in which it is moving. Nijhawan postulates that this may be the result of a mechanism that predicts the future position of the moving element so as to compensate for the fact that the element will have moved position from the time at which the light left it to the time at which the observer becomes aware of it (as a result of the finite time taken for neural transmission). There is an alternative explanation of this effect, however. Changes in the stimulus presentation could affect perceptual latency [2], and therefore the perceived position if in motion (as suggested for the Pulfrich pendulum effect [3] [4]). In other words, if the flashed probe of the Nijhawan demonstration takes longer to reach perceptual awareness than the moving stimulus, the latter will appear to be ahead of the probe. Here, I demonstrate an alternative way of testing this hypothesis. When an illusory movement is induced (via the motion aftereffect) within a stationary pattern, it can be shown that this also produces a change in its perceived spatial position. As the pattern is stationary, one cannot account for this result via the notion of perceptual lags.
当物体移动时，我们会感知到它处于何处？尼加万[1]报告称，如果一个静止的测试图案与一个移动的图案在空间上短暂对齐闪烁，移动的元素实际上会在其移动的方向上出现位移。尼加万推测，这可能是一种机制的结果，该机制预测移动元素的未来位置，以补偿从光离开该元素到观察者意识到它（由于神经传导所需的有限时间）这段时间内该元素将移动位置这一事实。然而，对这种效应还有另一种解释。刺激呈现的变化可能会影响感知潜伏期[2]，因此如果物体在运动，就会影响其感知位置（正如对普尔弗里希摆效应[3][4]所提出的那样）。换句话说，如果尼加万演示中的闪烁探针比移动刺激到达感知意识所需的时间更长，那么后者看起来会在探针之前。在此，我展示了一种检验这一假设的替代方法。当在一个静止图案中诱发虚幻运动（通过运动后效）时，可以证明这也会导致其感知空间位置发生变化。由于图案是静止的，无法通过感知滞后的概念来解释这一结果。
