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

Lookup NU author(s): Stacey Aston, Professor Anya Hurlbert

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

© 2018 The Authors. 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 fixedsurfaces 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.


Publication metadata

Author(s): Radonjic A, Ding X, Krieger A, Aston S, Hurlbert AC, Brainard DH

Publication type: Article

Publication status: Published

Journal: Journal of Vision

Year: 2018

Volume: 18

Issue: 5

Online publication date: 21/05/2018

Acceptance date: 26/12/2017

ISSN (electronic): 1534-7362

Publisher: Association for Research in Vision and Ophthalmology Inc.

URL: https://doi.org/10.1167/18.5.11

DOI: 10.1167/18.5.11


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