To accomplish the deceptively simple task of perceiving the size of objects in the visual scene, the visual system combines information about the retinal size of the object with several other cues, including perceived distance, relative size, and prior knowledge. When local component elements are perceptually grouped to form objects, the task is further complicated because a grouped object does not have a continuous contour from which retinal size can be estimated. Here, we investigate how the visual system solves this problem and makes it possible for observers to judge the size of perceptually grouped objects. We systematically vary the shape and orientation of the component elements in a two-alternative forced-choice task and find that the perceived size of the array of component objects can be almost perfectly predicted from the distance between the centroids of the component elements and the center of the array. This is true whether the global contour forms a circle or a square. When elements were positioned such that the centroids along the global contour were at different distances from the center, perceived size was based on the average distance. These results indicate that perceived size does not depend on the size of individual elements, and that smooth contours formed by the outer edges of the component elements are not used to estimate size. The current study adds to a growing literature highlighting the importance of centroids in visual perception and may have implications for how size is estimated for ensembles of different objects.

中文翻译：

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感知的组大小由组成元素的质心决定。

为了完成在视觉场景中感知物体大小的看似简单的任务，视觉系统将关于物体视网膜大小的信息与其他几个线索相结合，包括感知距离、相对大小和先验知识。当局部组件元素被感知分组以形成对象时，任务更加复杂，因为分组对象没有可以估计视网膜大小的连续轮廓。在这里，我们研究视觉系统如何解决这个问题，并使观察者能够判断感知分组对象的大小。我们在两个选择的强制选择任务中系统地改变组件元素的形状和方向，并发现组件对象数组的感知大小几乎可以从组件元素的质心和中心之间的距离完美预测的数组。无论全局轮廓是圆形还是正方形，都是如此。当元素的位置使得沿全局轮廓的质心与中心的距离不同时，感知大小基于平均距离。这些结果表明感知大小不依赖于单个元素的大小，并且由组成元素的外边缘形成的平滑轮廓不用于估计大小。