Patel Khushbu Y, Munasinghe Anudhi P, Murray Richard F
Department of Psychology and Centre for Vision Research, York University, Toronto, Canada.
Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA, USA.
J Vis. 2018 May 1;18(5):1. doi: 10.1167/18.5.1.
Lightness constancy is the ability to perceive surface reflectance correctly despite substantial changes in lighting intensity. A classic view is that lightness constancy is the result of a "discounting" of lighting intensity, and this continues to be a prominent view today. Logvinenko and Maloney (2006) have proposed an alternative approach to understanding lightness constancy, in which observers do not make explicit estimates of reflectance, and lightness constancy is instead based on a perceptual similarity metric that depends on both the reflectance and the illuminance of surfaces viewed under different lighting conditions. Here we compare these two views using a novel, free-adjustment reflectance-matching task. We test whether observers can match reflectance in a task where they are free to adjust both the illuminance and the reflectance of the match stimulus over a wide range. We find that observers can match reflectance under these conditions, which supports the view that observers make explicit estimates of reflectance. We also compare performance in this free adjustment task using physical objects and computer-rendered images as stimuli. We find that lightness constancy is good in both cases, but with some evidence of a glow-related artifact with computer-rendered stimuli.
明度恒常性是指即使光照强度发生显著变化，仍能正确感知表面反射率的能力。一种经典观点认为，明度恒常性是光照强度“折扣”的结果，如今这一观点仍然占据主导地位。洛维年科和马洛尼（2006年）提出了另一种理解明度恒常性的方法，即观察者不会对反射率进行明确估计，相反，明度恒常性基于一种感知相似性度量，该度量取决于在不同光照条件下观察到的表面的反射率和照度。在此，我们使用一种新颖的、自由调整反射率匹配任务来比较这两种观点。我们测试观察者在一项任务中是否能够匹配反射率，在该任务中他们可以在很宽的范围内自由调整匹配刺激的照度和反射率。我们发现观察者在这些条件下能够匹配反射率，这支持了观察者对反射率进行明确估计的观点。我们还比较了使用物理对象和计算机渲染图像作为刺激时在这项自由调整任务中的表现。我们发现两种情况下明度恒常性都很好，但有证据表明计算机渲染刺激存在与光晕相关的伪影。
