Caharel Stéphanie, Jiang Fang, Blanz Volker, Rossion Bruno
Unité Cognition et Développement, Université Catholique de Louvain, 1348 Louvain-la-Neuve, Belgium.
Neuroimage. 2009 Oct 1;47(4):1809-18. doi: 10.1016/j.neuroimage.2009.05.065. Epub 2009 Jun 1.
The human brain recognizes faces by means of two main diagnostic sources of information: three-dimensional (3D) shape and two-dimensional (2D) surface reflectance. Here we used event-related potentials (ERPs) in a face adaptation paradigm to examine the time-course of processing for these two types of information. With a 3D morphable model, we generated pairs of faces that were either identical, varied in 3D shape only, in 2D surface reflectance only, or in both. Sixteen human observers discriminated individual faces in these 4 types of pairs, in which a first (adapting) face was followed shortly by a second (test) face. Behaviorally, observers were as accurate and as fast for discriminating individual faces based on either 3D shape or 2D surface reflectance alone, but were faster when both sources of information were present. As early as the face-sensitive N170 component (approximately 160 ms following the test face), there was larger amplitude for changes in 3D shape relative to the repetition of the same face, especially over the right occipito-temporal electrodes. However, changes in 2D reflectance between the adapter and target face did not increase the N170 amplitude. At about 250 ms, both 3D shape and 2D reflectance contributed equally, and the largest difference in amplitude compared to the repetition of the same face was found when both 3D shape and 2D reflectance were combined, in line with observers' behavior. These observations indicate that evidence to recognize individual faces accumulate faster in the right hemisphere human visual cortex from diagnostic 3D shape information than from 2D surface reflectance information.
三维（3D）形状和二维（2D）表面反射率。在这里，我们在面孔适应范式中使用事件相关电位（ERP）来研究这两种信息处理的时间进程。我们使用一个3D可变形模型生成了几对面孔，这些面孔要么完全相同，要么仅在3D形状上有所不同，要么仅在2D表面反射率上有所不同，要么在两者上都有所不同。16名人类观察者对这4种类型的面孔对中的单个面孔进行辨别，其中第一张（适应）面孔之后很快会出现第二张（测试）面孔。在行为上，观察者基于单独的3D形状或2D表面反射率来辨别单个面孔时，准确性和速度相当，但当两种信息来源都存在时会更快。早在对面孔敏感的N170成分（测试面孔出现后约160毫秒），相对于同一张面孔的重复，3D形状变化的振幅更大，尤其是在右侧枕颞电极上方。然而，适应面孔和目标面孔之间2D反射率的变化并没有增加N170的振幅。在大约250毫秒时，3D形状和2D反射率的作用相当，并且当3D形状和2D反射率都结合时，与同一张面孔的重复相比，振幅差异最大，这与观察者的行为一致。这些观察结果表明，在人类视觉皮层的右半球中，从诊断性的3D形状信息中识别单个面孔的证据比从2D表面反射率信息中积累得更快。
