1Department of Psychology, University of Toronto.
Psychol Sci. 2014 Mar;25(3):745-52. doi: 10.1177/0956797613514451. Epub 2014 Jan 24.
Darwin theorized that emotional expressions originated as opposing functional adaptations for the expresser, not as distinct categories of social signals. Given that two thirds of the eye's refractive power comes from the cornea, we examined whether opposing expressive behaviors that widen the eyes (e.g., fear) or narrow the eyes (e.g., disgust) may have served as an optical trade-off, enhancing either sensitivity or acuity, thereby promoting stimulus localization ("where") or stimulus discrimination ("what"), respectively. An optical model based on eye apertures of posed fear and disgust expressions supported this functional trade-off. We then tested the model using standardized optometric measures of sensitivity and acuity. We demonstrated that eye widening enhanced stimulus detection, whereas eye narrowing enhanced discrimination, each at the expense of the other. Opposing expressive actions around the eye may thus reflect origins in an optical principle, shaping visual encoding at its earliest stage-how light is cast onto the retina.
达尔文推测，情绪表达最初是表达者的对立功能适应，而不是不同类别的社会信号。鉴于眼睛三分之二的屈光力来自于角膜，我们研究了扩大眼睛（例如恐惧）或缩小眼睛（例如厌恶）的对立表达行为是否可以作为一种光学权衡，从而提高敏感性或准确性，从而分别促进刺激定位（“在哪里”）或刺激辨别（“是什么”）。基于恐惧和厌恶表情的眼部孔径的光学模型支持这种功能权衡。然后，我们使用敏感性和准确性的标准化验光测量来测试该模型。我们证明了眼睛变宽可以增强对刺激的检测，而眼睛变窄则可以增强辨别力，各有各的代价。因此，眼睛周围的对立表达动作可能反映了在光学原理中的起源，从而塑造了视觉编码的最早阶段——光线是如何投射到视网膜上的。
