Foveal input is not required for perception of crowd facial expression.
Foveal input is not required for perception of crowd facial expression.
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DOI：
10.1167/15.4.11
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发表时间：
2015-09
影响因子：
1.8
通讯作者：
Benjamin Wolfe;Anna Kosovicheva;A. Leib;Katherine Wood;D. Whitney
中科院分区：
文献类型：
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作者：
Benjamin Wolfe;Anna Kosovicheva;A. Leib;Katherine Wood;D. Whitney
视觉系统从一组物体中提取平均特征（Ariely，2001; Dakin & Watt，1997; Watamaniuk & Sekirst，1992），包括高水平的刺激，如面部（Haberman & Whitney，2007，2009）。这种现象，被称为整体感知，意味着一个内隐过程，这将不需要固定的个别刺激元素。然而，一些证据表明，整体感知可能是一个在连续注视中平均中央凹输入的过程（Ji，Chen，& Fu，2013; Jung，Bulthoff，Thornton，Lee，& Armann，2013）。为了直接测试是否有必要对物体进行视觉中心凹，我们测量了观察者在没有视觉中心凹输入的情况下对平均面部情绪的敏感度。受试者观看24张面孔的阵列，无论是在存在或不存在的凝视特遣队中央凹遮挡，并调整测试面匹配的平均表达的阵列。我们发现在遮挡和非遮挡条件之间的准确性没有差异，表明中央凹输入是不需要的合奏感知。不出所料，在没有中央凹输入的情况下，受试者直接注视面部的时间明显减少，但这并没有转化为对整体表达的敏感性的任何差异。接下来，我们改变了集合中可见的面孔数量，以测试受试者是否平均了人群中的多张面孔。在这两种情况下，随着更多的面孔出现，受试者的表现有所改善，这表明受试者在显示器中整合了来自多个面孔的信息，而不管他们是否能够获得中央凹信息。我们的研究结果表明，整体感知可以是一个隐蔽的过程，不需要直接获得中央凹信息。
The visual system extracts average features from groups of objects (Ariely, 2001; Dakin & Watt, 1997; Watamaniuk & Sekuler, 1992), including high-level stimuli such as faces (Haberman & Whitney, 2007, 2009). This phenomenon, known as ensemble perception, implies a covert process, which would not require fixation of individual stimulus elements. However, some evidence suggests that ensemble perception may instead be a process of averaging foveal input across sequential fixations (Ji, Chen, & Fu, 2013; Jung, Bulthoff, Thornton, Lee, & Armann, 2013). To test directly whether foveating objects is necessary, we measured observers' sensitivity to average facial emotion in the absence of foveal input. Subjects viewed arrays of 24 faces, either in the presence or absence of a gaze-contingent foveal occluder, and adjusted a test face to match the average expression of the array. We found no difference in accuracy between the occluded and non-occluded conditions, demonstrating that foveal input is not required for ensemble perception. Unsurprisingly, without foveal input, subjects spent significantly less time directly fixating faces, but this did not translate into any difference in sensitivity to ensemble expression. Next, we varied the number of faces visible from the set to test whether subjects average multiple faces from the crowd. In both conditions, subjects' performance improved as more faces were presented, indicating that subjects integrated information from multiple faces in the display regardless of whether they had access to foveal information. Our results demonstrate that ensemble perception can be a covert process, not requiring access to direct foveal information.