Stürzel F, Spillmann L
Institute of Biophysics and Radiation Biology, Brain Research Unit, University of Freiburg, Hansastrasse 9, D-79104 Freiburg, Germany.
Perception. 2000;29(8):937-42. doi: 10.1068/p2888.
The expression of a face with its eyes and mouth inverted changes from 'pleasant' to 'grotesque' as the stimulus is rotated from 180 degrees to 0 degree (Thatcher illusion). We determined the angular orientation at which this change occurred for three manipulated faces. Mean thresholds for eighteen observers were found to lie between 94 degrees and 100 degrees relative to the vertical with an average overlap of about 15 degrees between an observer's ascending and descending thresholds. The sudden nature and relatively narrow zone of the changeover suggest a neuronal step-tuning of hypothetical face cells in the human brain, underlying the holistic ('grotesque') versus componential ('pleasant') processing of upright versus upside-down faces. Findings are discussed within the framework of cognitive, neuroimaging, and single-cell studies.
当刺激从180度旋转到0度时，眼睛和嘴巴倒置的面部表情会从“愉悦”变为“怪异”（撒切尔错觉）。我们确定了三个经过处理的面部出现这种变化时的角度方向。相对于垂直方向，18名观察者的平均阈值在94度至100度之间，观察者的上升阈值和下降阈值之间平均重叠约15度。这种转变的突然性和相对较窄的区域表明，人脑中假设的面部细胞存在神经元阶梯调谐，这是对面部正立与倒置的整体（“怪异”）与成分（“愉悦”）处理的基础。研究结果在认知、神经成像和单细胞研究的框架内进行了讨论。
