Greenlee M W, Heitger F
Neurologische Universitätsklinik mit Abteilung für Neurophysiologie, Freiburg im Br., F.R.G.
Vision Res. 1988;28(7):791-7. doi: 10.1016/0042-6989(88)90026-0.
Prolonged inspection of high contrast sinewave gratings increases the contrast required to detect gratings having a similar spatial frequency and orientation. The functional role of such adaptation has, however, in the past, eluded disclosure. We here show that 5 min adaptation to a 2 c/deg sinewave grating of 0.8 contrast changes the observer's ability to discriminate the contrast level of a subsequently presented grating of the same spatial frequency and orientation. Similar to the threshold elevation effect, the observers required more incremental contrast for background contrast levels between 0.1 and 0.4 following adaptation. However, for contrast levels above 0.5, the observers required less delta contrast, following adaptation, to correctly discriminate which of two gratings was incremented in contrast. A simple model for adaptation is proposed to account for the findings which is based on a shift in the semi-saturation constant of the detector's contrast-response function. According to this model, adaptation acts to linearize the underlying mechanism's response in the region near the prevailing contrast level.
对高对比度正弦波光栅进行长时间观察会提高检测具有相似空间频率和方向的光栅所需的对比度。然而，过去这种适应性的功能作用一直未被揭示。我们在此表明，对对比度为0.8的2 c/deg正弦波光栅进行5分钟的适应会改变观察者辨别随后呈现的相同空间频率和方向光栅的对比度水平的能力。与阈值升高效应类似，适应后，对于背景对比度水平在0.1至0.4之间的情况，观察者需要更多的增量对比度。然而，对于高于0.5的对比度水平，适应后观察者正确辨别两个光栅中哪个对比度增加所需的增量对比度更少。提出了一个简单的适应模型来解释这些发现，该模型基于探测器对比度响应函数的半饱和常数的变化。根据该模型，适应作用是使基础机制在当前对比度水平附近区域的响应线性化。
