Kristjánsson Árni
Department of Psychology, School of Health Sciences, University of Iceland, Reykjavik, Iceland.
J Opt Soc Am A Opt Image Sci Vis. 2012 Jun 1;29(6):1180-7. doi: 10.1364/JOSAA.29.001180.
The range of variation in environmental stimuli is much larger than the visual system can represent. It is therefore sensible for the system to adjust its responses to the momentary input statistics of the environment, such as when our pupils contract to limit the light entering the eye. Previous evidence indicates that the visual system increasingly centers responses on the mean of the visual input and scales responses to its variation during adaptation. To what degree does adaptation to a stimulus varying in luminance over time result in such adjustment of responses? The first two experiments were designed to test whether sensitivity to changes in the amplitude and the mean of a 9.6° central patch varying sinusoidally in luminance at 0.6 Hz would increase or decrease with adaptation. This was also tested for a dynamic peripheral stimulus (random patches rotating on the screen) to test to what extent the effects uncovered in the first two experiments reflect retinotopic mechanisms. Sensitivity to changes in mean and amplitude of the temporal luminance variation increased sharply the longer the adaptation to the variation, both for the large patch and the peripheral patches. Adaptation to luminance variation leads to increased sensitivity to temporal luminance variation for both central and peripheral presentation, the latter result ruling retinotopic mechanisms out as sole explanations for the adaptation effects.
环境刺激的变化范围远大于视觉系统所能呈现的范围。因此，对于该系统而言，根据环境的瞬时输入统计信息来调整其反应是明智的，比如当我们的瞳孔收缩以限制进入眼睛的光线时。先前的证据表明，在适应过程中，视觉系统会越来越多地将反应集中在视觉输入的平均值上，并根据其变化来调整反应的尺度。对随时间亮度变化的刺激的适应在多大程度上会导致这种反应调整呢？前两个实验旨在测试对一个在0.6赫兹频率下亮度呈正弦变化的9.6°中央斑块的幅度和平均值变化的敏感度是否会随着适应而增加或降低。对于动态周边刺激（屏幕上旋转的随机斑块）也进行了此项测试，以检验在前两个实验中发现的效应在多大程度上反映了视网膜拓扑机制。对于大斑块和周边斑块，对时间亮度变化的平均值和幅度变化的敏感度随着对该变化的适应时间延长而急剧增加。对亮度变化的适应会导致对中央和周边呈现的时间亮度变化的敏感度增加，后一个结果排除了视网膜拓扑机制作为适应效应的唯一解释。
