Emotional expressions are quickly and automatically read from human faces under natural viewing conditions. Yet, categorization of facial expressions is typically measured in experimental contexts with homogenous sets of face stimuli. Here we evaluated how the 6 basic facial emotions (Fear, Disgust, Happiness, Anger, Surprise or Sadness) can be rapidly and automatically categorized with faces varying in head orientation, lighting condition, identity, gender, age, ethnic origin and background context. High-density electroencephalography was recorded in 17 participants viewing 50 s sequences with natural variable images of neutral-expression faces alternating at a 6 Hz rate. Every five stimuli (1.2 Hz), variable natural images of one of the six basic expressions were presented. Despite the wide physical variability across images, a significant F/5 = 1.2 Hz response and its harmonics (e.g., 2F/5 = 2.4 Hz, etc.) was observed for all expression changes at the group-level and in every individual participant. Facial categorization responses were found mainly over occipito-temporal sites, with distinct hemispheric lateralization and cortical topographies according to the different expressions. Specifically, a stronger response was found to Sadness categorization, especially over the left hemisphere, as compared to Fear and Happiness, together with a right hemispheric dominance for categorization of Fearful faces. Importantly, these differences were specific to upright faces, ruling out the contribution of low-level visual cues. Overall, these observations point to robust rapid and automatic facial expression categorization processes in the human brain.

在自然观看条件下，可以快速自动地从人脸中读取情绪表达。然而，面部表情的分类通常是在具有同质面部刺激集的实验环境中测量的。在这里，我们评估了 6 种基本面部情绪（恐惧、厌恶、幸福、愤怒、惊讶或悲伤）) 可以根据头部方向、照明条件、身份、性别、年龄、种族起源和背景背景而变化的面部快速自动分类。在 17 名参与者中记录了高密度脑电图，这些参与者观看了 50 秒序列，其中性表情面部的自然可变图像以 6 赫兹的频率交替。每五个刺激（1.2 Hz），呈现六种基本表情之一的可变自然图像。尽管图像之间存在广泛的物理变异性，但在组级别和每个参与者的所有表达变化中都观察到了显着的 F/5 = 1.2 Hz 响应及其谐波（例如，2F/5 = 2.4 Hz 等）。面部分类反应主要出现在枕颞部位，根据不同的表情，具有明显的半球侧化和皮质地形。具体而言，与恐惧和幸福相比，发现对悲伤分类的反应更强，尤其是在左半球，而对恐惧面孔的分类则右半球占主导地位。重要的是，这些差异特定于直立的面孔，排除了低级视觉线索的贡献。总体而言，这些观察结果表明人脑中强大的快速和自动面部表情分类过程。这些差异特定于直立的面孔，排除了低级视觉线索的贡献。总体而言，这些观察结果表明人脑中强大的快速和自动面部表情分类过程。这些差异特定于直立的面孔，排除了低级视觉线索的贡献。总体而言，这些观察结果表明人脑中具有强大的快速和自动面部表情分类过程。