In a stimulus with multiple moving elements, an observer may perceive that the whole stimulus moves in unison if (a) one can associate an element in one frame with one in the next (correspondence) and (b) a sufficient proportion of correspondences signal a similar motion direction (coherence). We tested the necessity of these two conditions by asking the participants to rate the perceived intensity of linear, concentric, and radial motions for three types of stimuli: (a) random walk motion, in which the direction of each dot was randomly determined for each frame, (b) random image sequence, which was a set of uncorrelated random dot images presented in sequence, and (c) global motion, in which 35% of dots moved coherently. The participants perceived global motion not only in the global motion conditions but also in the random image sequences, though not in random walk motion. The type of perceived motion in the random image sequences depends on the spatial context of the stimuli. Thus, although there is neither a fixed correspondence across different frames nor a coherent motion direction, observers can still perceive global motion in the random image sequence. This result cannot be explained by motion energy or local aperture border effects.

中文翻译：

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在随机点图像序列中查看全局运动

在具有多个移动元素的刺激中，如果（a）人们可以将一帧中的元素与下一帧中的元素（对应）相关联，并且（b）足够比例的对应信号 a相似的运动方向（相干性）。我们通过要求参与者对三种类型的刺激的线性、同心和径向运动的感知强度进行评分来测试这两个条件的必要性：(a) 随机行走运动，其中每个点的方向是随机确定的帧，（b）随机图像序列，这是一组按顺序呈现的不相关的随机点图像，以及（c）全局运动，其中 35% 的点连贯地移动。参与者不仅在全局运动条件下而且在随机图像序列中感知全局运动，虽然不是随机行走运动。随机图像序列中感知运动的类型取决于刺激的空间背景。因此，尽管不同帧之间既没有固定的对应关系，也没有连贯的运动方向，但观察者仍然可以感知随机图像序列中的全局运动。这个结果不能用运动能量或局部孔径边界效应来解释。