Boutsen Luc, Humphreys Glyn W, Praamstra Peter, Warbrick Tracy
School of Life and Health Sciences, Aston University, Birmingham B4 7ET, UK.
Neuroimage. 2006 Aug 1;32(1):352-67. doi: 10.1016/j.neuroimage.2006.03.023. Epub 2006 Apr 24.
In the Thatcher illusion, a face with inverted eyes and mouth looks abnormal when upright but not when inverted. Behavioral studies have shown that thatcherization of an upright face disrupts perceptual processing of the local configuration. We recorded high-density EEG from normal observers to study ERP correlates of the illusion during the perception of faces and nonface objects, to determine whether inversion and thatcherization affect similar neural mechanisms. Observers viewed faces and houses in four conditions (upright vs. inverted, and normal vs. thatcherized) while detecting an oddball category (chairs). Thatcherization delayed the N170 component over occipito-temporal cortex to faces, but not to houses. This modulation matched the illusion as it was larger for upright than inverted faces. The P1 over medial occipital regions was delayed by face inversion but unaffected by thatcherization. Finally, face thatcherization delayed P2 over occipito-temporal but not over parietal regions, while inversion affected P2 across categories. All effects involving thatcherization were face-specific. These results indicate that effects of face inversion and feature inversion (in thatcherized faces) can be distinguished on a functional as well as neural level, and that they affect configural processing of faces in different time windows.
在撒切尔错觉中，眼睛和嘴巴倒置的脸在正立时看起来异常，但倒立时则不然。行为研究表明，正立脸的撒切尔化会扰乱局部构型的感知处理。我们记录了正常观察者的高密度脑电图，以研究在对面部和非面部物体的感知过程中错觉的事件相关电位（ERP）相关性，以确定倒置和撒切尔化是否影响相似的神经机制。观察者在检测异常类别（椅子）时，在四种条件下（正立与倒立，正常与撒切尔化）观察面部和房屋。撒切尔化使枕颞叶皮质上对面部的N170成分延迟，但对房屋则不然。这种调制与错觉相匹配，因为正立脸比倒立脸的调制更大。内侧枕叶区域的P1因面部倒置而延迟，但不受撒切尔化影响。最后，面部撒切尔化使枕颞叶区域的P2延迟，但顶叶区域则不然，而倒置则影响不同类别的P2。所有涉及撒切尔化的效应都是面部特异性的。这些结果表明，面部倒置和特征倒置（在撒切尔化的面部中）的效应在功能以及神经水平上都可以区分，并且它们在不同的时间窗口影响面部的构型处理。
