Laeng Bruno, Canoluk Hüseyin Berke, Nabil Shoaib
Department of Psychology, University of Oslo, Oslo, Norway.
RITMO Centre for Interdisciplinary Studies in Rhythm, Time and Motion, University of Oslo, Oslo, Norway.
Front Hum Neurosci. 2025 Aug 26;19:1604114. doi: 10.3389/fnhum.2025.1604114. eCollection 2025.
Using infrared eye tracking, we show that when gaze is maintained at the center of one of two equiluminant surfaces of a Cornsweet stimulus, designed by Lotto and Purves, that illusorily appear to be lighter or darker than the other, the eye pupils constrict or dilate, respectively. That is, pupil sizes mirror the subjective experience of differential brightness. Previous studies of pupil responses to illusions of light had focused on illusions of unveridical light sources (e.g., patterns resembling the sun), whereas in the present study, we show pupil adjustments to the illusory brightness of object surfaces within images of realistic scenes. In two control experiments, we also showed that when the edge gradients of the Cornsweet stimulus, which do differ in luminance, were either occluded or presented alone in a black field, there were no differences in pupil diameters. We also conclude that adjustments to the perception of surface reflectance are unlikely to represent anticipatory responses to probable risks of temporary visual impairment (i.e., dazzle to sunlight) and, instead, indicate that a gradual process of disambiguation of the visual scene is sufficient to elicit adjustments to the apparent light intensity of an object's surface.
通过红外眼动追踪，我们发现，当注视点保持在由洛托和珀维斯设计的科恩斯威特刺激的两个等亮度表面之一的中心时（这两个表面会产生错觉，看起来一个比另一个更亮或更暗），眼睛瞳孔会分别收缩或扩张。也就是说，瞳孔大小反映了亮度差异的主观体验。先前关于瞳孔对光错觉反应的研究主要集中在非真实光源的错觉上（例如，类似太阳的图案），而在本研究中，我们展示了瞳孔对现实场景图像中物体表面错觉亮度的调整。在两个对照实验中，我们还表明，当科恩斯威特刺激中确实存在亮度差异的边缘梯度被遮挡或单独呈现在黑色背景中时，瞳孔直径没有差异。我们还得出结论，对表面反射率感知的调整不太可能代表对暂时视力受损（即阳光眩光）可能风险的预期反应，相反，这表明视觉场景的逐步解歧义过程足以引发对物体表面表观光强度的调整。
