Luminance-induced shift in the apparent direction of gaze

Area of Science:

• Visual perception
• Ophthalmology
• Psychophysics

Background:

• The perceived direction of gaze is crucial for social interaction and visual guidance.
• Existing research primarily focuses on iris position and head orientation as gaze cues.
• The role of scleral luminance in modulating gaze perception remains underexplored.

Purpose of the Study:

• To investigate the impact of scleral luminance changes on the perceived direction of gaze.
• To quantify the magnitude of luminance-induced gaze shifts.
• To compare the influence of scleral luminance cues with iris position cues.

Main Methods:

• Experiments utilized photographic and schematic eye images with controlled scleral luminance variations.
• Participants reported perceived gaze direction under different luminance conditions.
• The effects of scleral luminance and iris shifts were measured independently and combined.

Main Results:

• Darkening one side of the sclera induced a substantial apparent gaze shift towards the darker area (8-15+ degrees).
• Luminance-induced gaze shifts and iris-shift-induced gaze shifts were found to act on a common perceptual level.
• The observed luminance cue effect was weaker than predicted by simple luminance-based models.

Conclusions:

• Scleral luminance is a significant, albeit underestimated, cue for determining perceived gaze direction.
• Low-level analysis of the eye's luminance configuration plays a critical role in gaze perception.
• Further research is needed to fully elucidate the mechanisms underlying luminance-based gaze judgments.