Yorzinski Jessica L, Thorstenson Christopher A, Nguyen Trezze P
Department of Ecology and Conservation Biology, Texas A&M University, College Station, TX, United States.
Department of Psychology and Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI, United States.
Front Psychol. 2021 Mar 9;12:632616. doi: 10.3389/fpsyg.2021.632616. eCollection 2021.
The white sclera is important in facilitating gaze perception in humans. Iris color may likewise influence gaze perception but no previous studies have directly assessed its effect. We therefore examined how the interaction between sclera and iris color influences human gaze perception. We recorded the eye movements of human participants as they performed a visual search task with human faces exhibiting directed or averted gaze. The faces either exhibited light or dark irises. In addition, the faces had sclera that were depigmented (white) or pigmented (matched the color of the iris). We found that participants were quick and accurate in evaluating gaze regardless of iris color in faces with depigmented sclera. When the sclera were pigmented, participants were slower to evaluate the gaze of faces with both light and dark irises but these effects were most pronounced in the faces with dark irises. Furthermore, participants were generally less accurate in assessing faces with pigmented sclera when the irises were dark rather than light. Our results suggest that depigmented sclera are especially important for gaze perception in faces with dark irises. Because depigmented sclera likely evolved at a time when ancestral humans exhibited dark irises, the depigmented sclera may have been crucial for efficient and accurate gaze perception in ancestral humans.
白色巩膜对促进人类的注视感知很重要。虹膜颜色可能同样会影响注视感知，但此前尚无研究直接评估其影响。因此，我们研究了巩膜和虹膜颜色之间的相互作用如何影响人类的注视感知。我们记录了人类参与者在执行视觉搜索任务时的眼动情况，任务中呈现的人脸具有直视或回避的目光。这些人脸的虹膜要么是浅色，要么是深色。此外，人脸的巩膜要么是无色素沉着的（白色），要么是有色素沉着的（与虹膜颜色匹配）。我们发现，对于巩膜无色素沉着的人脸，无论虹膜颜色如何，参与者在评估目光时都快速且准确。当巩膜有色素沉着时，参与者评估浅色和深色虹膜人脸的目光速度较慢，但这些影响在深色虹膜人脸中最为明显。此外，当虹膜为深色而非浅色时，参与者评估巩膜有色素沉着的人脸时通常准确性较低。我们的结果表明，无色素沉着的巩膜对于深色虹膜人脸的注视感知尤为重要。由于无色素沉着的巩膜可能是在人类祖先虹膜为深色时进化而来的，因此无色素沉着的巩膜可能对人类祖先高效准确的注视感知至关重要。
