Ricou Camille, Rabadan Vivien, Mofid Yassine, Aguillon-Hernandez Nadia, Wardak Claire
Université de Tours, INSERM, Imaging Brain & Neuropsychiatry iBraiN U1253, Tours 37032, France.
Soc Cogn Affect Neurosci. 2024 Sep 16;19(1). doi: 10.1093/scan/nsae055.
Human facial features (eyes, nose, and mouth) allow us to communicate with others. Observing faces triggers physiological responses, including pupil dilation. Still, the relative influence of social and motion content of a visual stimulus on pupillary reactivity has never been elucidated. A total of 30 adults aged 18-33 years old were recorded with an eye tracker. We analysed the event-related pupil dilation in response to stimuli distributed along a gradient of social salience (non-social to social, going from objects to avatars to real faces) and dynamism (static to micro- to macro-motion). Pupil dilation was larger in response to social (faces and avatars) compared to non-social stimuli (objects), with surprisingly a larger response for avatars. Pupil dilation was also larger in response to macro-motion compared to static. After quantifying each stimulus' real quantity of motion, we found that the higher the quantity of motion, the larger the pupil dilated. However, the slope of this relationship was not higher for social stimuli. Overall, pupil dilation was more sensitive to the real quantity of motion than to the social component of motion, highlighting the relevance of ecological stimulations. Physiological response to faces results from specific contributions of both motion and social processing.
人类的面部特征（眼睛、鼻子和嘴巴）使我们能够与他人交流。观察面部会引发生理反应，包括瞳孔扩张。然而，视觉刺激的社会和运动内容对瞳孔反应性的相对影响从未得到阐明。共有30名年龄在18至33岁之间的成年人使用眼动仪进行记录。我们分析了与事件相关的瞳孔扩张，以响应沿着社会显著性梯度（从非社会到社会，从物体到虚拟形象再到真实面孔）和动态性梯度（从静态到微运动再到宏观运动）分布的刺激。与非社会刺激（物体）相比，对社会刺激（面孔和虚拟形象）的瞳孔扩张更大，令人惊讶的是，对虚拟形象的反应更大。与静态相比，对宏观运动的瞳孔扩张也更大。在量化每个刺激的实际运动量后，我们发现运动量越高，瞳孔扩张越大。然而，这种关系的斜率在社会刺激中并不更高。总体而言，瞳孔扩张对实际运动量比对运动的社会成分更敏感，突出了生态刺激的相关性。对面部的生理反应是运动和社会处理的特定贡献的结果。
