Schirillo J A, Shevell S K
Department of Psychology, University of Chicago, IL 60637, USA.
Perception. 1997;26(4):507-18. doi: 10.1068/p260507.
Achromatic brightness matches between two small patches were measured in a display containing ten larger regions of different luminances. The spatial organization of the ten regions was varied while keeping constant the immediate surround (and thus local contrast) of each patch as well as the average luminance of the entire stimulus. Various spatial arrangements were designed to alter the illumination inferred by the observer without changing the ensemble of luminances actually in view. Some spatial arrangements of the ten regions were consistent with five (simulated) surfaces under two distinct levels of illumination, with one luminance edge within the display (an 'apparent illumination edge') dividing the stimuli into an area of lower illumination and an area of higher illumination. In other spatial arrangements the ten regions were configured so that no luminance edge in the display could be interpreted as an ecologically valid illumination edge that provides a parsimonious interpretation of the ten regions; these conditions were designed to induce observers to infer ten surfaces under a single illuminant. When the ten regions were arranged with an apparent illumination edge, the patch within the area of lower perceived illumination was perceived as dimmer than when the same patch and immediate surround were presented with no apparent illumination edge. The results are interpreted by positing that the apparent illumination edge causes an observer to group together regions under the same perceived illuminant, with a consequent effect on brightness: lowering or raising the level of a perceived illuminant causes a patch of fixed contrast to be perceived as less bright or more bright, respectively, just as occurs when lowering or raising the level of real illumination. It is suggested that changes in brightness in a complex scene that result from a change in real illumination may be caused by a difference in inferred illumination at the perceptual level, not by simply a change in the amount of light absorbed by photoreceptors.
在一个包含十个不同亮度较大区域的显示屏中，测量了两个小色块之间的消色差亮度匹配。在保持每个色块的直接周边环境（以及局部对比度）和整个刺激的平均亮度不变的情况下，改变了这十个区域的空间组织。设计了各种空间排列方式，以改变观察者推断的照明情况，而不改变实际看到的亮度组合。十个区域的某些空间排列与在两种不同照明水平下的五个（模拟）表面一致，显示屏内有一个亮度边缘（“表观照明边缘”）将刺激分为较低照明区域和较高照明区域。在其他空间排列中，十个区域的配置使得显示屏中的任何亮度边缘都不能被解释为对这十个区域提供简约解释的生态有效照明边缘；这些条件旨在促使观察者推断在单一光源下的十个表面。当十个区域以表观照明边缘排列时，与没有表观照明边缘呈现相同色块和直接周边环境相比，在较低感知照明区域内的色块被感知为更暗。通过假设表观照明边缘会使观察者将处于相同感知光源下的区域归为一组，从而对亮度产生影响来解释这些结果：降低或提高感知光源的水平会使具有固定对比度的色块分别被感知为更暗或更亮，就如同降低或提高实际照明水平时发生的情况一样。有人提出，复杂场景中由实际照明变化导致的亮度变化可能是由感知层面推断照明的差异引起的，而不仅仅是由光感受器吸收的光量变化引起的。
