Queensland University of Technology.
Swinburne University of Technology, Melbourne, Australia.
J Cogn Neurosci. 2021 Feb;33(2):303-314. doi: 10.1162/jocn_a_01656. Epub 2020 Dec 7.
Face inversion effects occur for both behavioral and electrophysiological responses when people view faces. In EEG, inverted faces are often reported to evoke an enhanced amplitude and delayed latency of the N170 ERP. This response has been attributed to the indexing of specialized face processing mechanisms within the brain. However, inspection of the literature revealed that, although N170 is consistently delayed to a variety of face representations, only photographed faces invoke enhanced N170 amplitudes upon inversion. This suggests that the increased N170 amplitudes to inverted faces may have other origins than the inversion of the face's structure. We hypothesize that the unique N170 amplitude response to inverted photographed faces stems from multiple expectation violations, over and above structural inversion. For instance, rotating an image of a face upside-down not only violates the expectation that faces appear upright but also lifelong priors about illumination and gravity. We recorded EEG while participants viewed face stimuli (upright vs. inverted), where the faces were illuminated from above versus below, and where the models were photographed upright versus hanging upside-down. The N170 amplitudes were found to be modulated by a complex interaction between orientation, lighting, and gravity factors, with the amplitudes largest when faces consistently violated all three expectations. These results confirm our hypothesis that face inversion effects on N170 amplitudes are driven by a violation of the viewer's expectations across several parameters that characterize faces, rather than a disruption in the configurational disposition of its features.
当人们观看面部时，会出现行为和电生理反应的面部反转效应。在脑电图（EEG）中，常报告倒置的面部会引起 N170 事件相关电位（ERP）的振幅增强和潜伏期延迟。这一反应归因于大脑中专门的面部处理机制的索引。然而，文献回顾表明，尽管 N170 对于各种面部表现形式的延迟是一致的，但只有拍摄的面部在倒置时会引起 N170 振幅的增强。这表明，倒置面部的 N170 振幅增加可能源于面部结构倒置之外的其他原因。我们假设，倒置拍摄的面部引起的独特的 N170 振幅反应源于多重预期违反，超出了结构倒置。例如，将面部图像倒置不仅违反了面部直立出现的预期，还违反了关于照明和重力的终身先验。我们在参与者观看面部刺激（直立与倒置）时记录了脑电图，其中面部的照明来自上方与下方，以及模型的拍摄是直立的还是倒挂的。发现 N170 振幅受到方向、照明和重力因素的复杂相互作用的调节，当面部一致违反所有三个预期时，振幅最大。这些结果证实了我们的假设，即 N170 振幅对面部反转效应的驱动是由违反了几个特征描述面部的参数的观察者的期望引起的，而不是由其特征的配置布置的中断引起的。
