Illumination discrimination in the absence of a fixed surface-reflectance layout

Radonjić, Ana; Ding, Xiaomao; Krieger, Avery; Aston, Stacey; Hurlbert, Anya C.; Brainard, David H.

Abstract

Previous studies have shown that humans can discriminate spectral changes in illumination and that this sensitivity depends both on the chromatic direction of the illumination change and on the ensemble of surfaces in the scene. These studies, however, always used stimulus scenes with a fixed surface-reflectance layout. Here we compared illumination discrimination for scenes in which the surface reflectance layout remains fixed (fixed-surfaces condition) to those in which surface reflectances were shuffled randomly across scenes, but with the mean scene reflectance held approximately constant (shuffled-surfaces condition). Illumination discrimination thresholds in the fixed-surfaces condition were commensurate with previous reports. Thresholds in the shuffled-surfaces condition, however, were considerably elevated. Nonetheless, performance in the shuffled-surfaces condition exceeded that attainable through random guessing. Analysis of eye fixations revealed that in the fixed-surfaces condition, low illumination discrimination thresholds (across observers) were predicted by low overall fixation spread and high consistency of fixation location and fixated surface reflectances across trial intervals. Performance in the shuffled-surfaces condition was not systematically related to any of the eye-fixation characteristics we examined for that condition, but was correlated with performance in the fixed-surfaces condition.

Citation

Radonjić, A., Ding, X., Krieger, A., Aston, S., Hurlbert, A. C., & Brainard, D. H. (2018). Illumination discrimination in the absence of a fixed surface-reflectance layout. Journal of Vision, 18(5), Article 11. https://doi.org/10.1167/18.5.11

• Journal Article Type: Article
• Online Publication Date: May 21, 2018
• Publication Date: May 21, 2018
• Deposit Date: Jun 14, 2018
• Publicly Available Date: Jun 14, 2018
• Journal: Journal of Vision
• Electronic ISSN: 1534-7362
• Publisher: Association for Research in Vision and Ophthalmology
• Peer Reviewed: Peer Reviewed
• Volume: 18
• Issue: 5
• Article Number: 11
• DOI: https://doi.org/10.1167/18.5.11
• Public URL: https://durham-repository.worktribe.com/output/1328942