Afraz Seyed-Reza, Cavanagh Patrick
Department of Psychology, Harvard University, 33 Kirkland Street, Cambridge, MA 02138, USA.
Vision Res. 2008 Jan;48(1):42-54. doi: 10.1016/j.visres.2007.10.028.
Physiological results for the size of face-specific units in inferotemporal cortex (IT) support an extraordinarily large range of possible sizes--from 2.5 degrees to 30 degrees or more. We use a behavioral test of face-specific aftereffects to measure the face analysis regions and find a coarse retinotopy consistent with receptive fields of intermediate size (10 degrees -12 degrees at 3 degrees eccentricity). In the first experiment, observers were adapted to a single face at 3 degrees from fixation. A test (a morph of the face and its anti-face) was then presented at different locations around fixation and subjects classified it as face or anti-face. The face aftereffect (FAE) was not constant at all test locations--it dropped to half its maximum value for tests 5 degrees from the adapting location. Simultaneous adaptation to both a face and its anti-face, placed at opposite locations across fixation, produced two separate regions of opposite aftereffects. However, with four stimuli, faces alternating with anti-faces equally spaced around fixation, the FAE was greatly reduced at all locations, implying a fairly coarse localization of the aftereffect. In the second experiment, observers adapted to a face and its anti-face presented either simultaneously or in alternation. Results showed that the simultaneous presentation of a face and its anti-face leads to stronger FAEs than sequential presentation, suggesting that face processing has a dynamic nature and its region of analysis is sharpened when there is more than one face in the scene. In the final experiment, a face and two anti-face flankers with different spatial offsets were presented during adaptation and the FAE was measured at the face location. Results showed that FAE at the face location was inhibited more as the distance of anti-face flankers to the face stimulus was reduced. This confirms the spatial extent of face analysis regions in a test with a fixed number of stimuli where only distance varied.
颞下皮质（IT）中面部特异性单元大小的生理学结果支持了一系列非常大的可能大小范围——从2.5度到30度或更大。我们使用面部特异性后效的行为测试来测量面部分析区域，并发现了一种与中等大小感受野（在3度偏心率下为10度-12度）一致的粗略视网膜拓扑结构。在第一个实验中，观察者适应了一个在离注视点3度处的单一面孔。然后在注视点周围的不同位置呈现一个测试刺激（该面孔与其反面孔的变形），并让受试者将其分类为面孔或反面孔。面部后效（FAE）在所有测试位置并非恒定不变——在离适应位置5度的测试中，它降至最大值的一半。同时适应位于注视点两侧相对位置的面孔及其反面孔，会产生两个相反后效的独立区域。然而，对于四个刺激，面孔与反面孔在注视点周围等距交替出现时，FAE在所有位置都大大降低，这意味着后效的定位相当粗略。在第二个实验中，观察者适应同时或交替呈现的面孔及其反面孔。结果表明，面孔及其反面孔同时呈现比顺序呈现会导致更强的FAE，这表明面部处理具有动态性质，并且当场景中有多个面孔时，其分析区域会更加清晰。在最后一个实验中，在适应过程中呈现一个面孔和两个具有不同空间偏移的反面孔侧翼，并在面孔位置测量FAE。结果表明，随着反面孔侧翼与面孔刺激距离的减小，面孔位置的FAE受到的抑制作用更强。这在一个只有距离变化的固定数量刺激的测试中，证实了面部分析区域的空间范围。
