Data_Sheet_1_Pupil Size as a Gateway Into Conscious Interpretation of Brightness.docx

Although retinal illumination is the main determinant of pupil size, evidence indicates that extra-retinal factors, including attention and contextual information, also modulate the pupillary response. For example, stimuli that evoke the idea of brightness (e.g., pictures of the sun) induce pupillary constriction compared to control stimuli of matched luminance. Is conscious appraisal of these stimuli necessary for the pupillary constriction to occur? Participants' pupil diameter was recorded while sun pictures and their phase-scrambled versions were shown to the left eye. A stream of Mondrian patterns was displayed to the right eye to produce continuous flash suppression, which rendered the left-eye stimuli invisible on some trials. Results revealed that when participants were aware of the sun pictures their pupils constricted relative to the control stimuli. This was not the case when the pictures were successfully suppressed from awareness, demonstrating that pupil size is highly sensitive to the contents of consciousness.

尽管视网膜照度是决定瞳孔大小的主要因素，但已有研究证实，包括注意力与情境信息在内的视网膜外因素，同样可对瞳孔反应产生调节作用。例如，与亮度匹配的对照刺激相比，能够唤起亮度感知的刺激（如太阳图片）可引发瞳孔收缩。那么，瞳孔收缩的发生是否依赖于个体对这类刺激的有意识评估？实验过程中，向被试左眼呈现太阳图片及其相位打乱版本，同时记录其瞳孔直径；向被试右眼呈现连续的蒙德里安图案以诱发连续闪烁抑制（continuous flash suppression），使得部分试次中左眼呈现的刺激无法被被试觉知。结果显示，当被试能够觉知到太阳图片时，其瞳孔相较于对照刺激出现收缩；而当太阳图片成功被抑制于意识之外时，则未观察到该效应。这一发现表明，瞳孔大小对意识内容具有高度敏感性。