Yang J, Qi X, Makous W
Center for Visual Science, University of Rochester, NY 14627, USA.
Vision Res. 1995 Jul;35(14):1965-78. doi: 10.1016/0042-6989(94)00285-t.
Stimulating the visual system tends to desensitize it to certain stimulus properties. Such desensitization is usually called adaptation or masking, but the distinction between the two is unclear. Nonspecific desensitization by light is usually regarded as adaptation, whereas pattern-specific desensitization is typically considered masking. Here we unify the treatment of such desensitizing phenomena by handling both in the spatial frequency domain. The amount of adapting light in a stimulus is represented in the spatial frequency domain by the component at zero frequency. To determine whether such adapting light acts like other components in the spatial frequency domain, we compared the effect of masking by the zero frequency component with the effects of masking by components at other frequencies. We show that the zero frequency component acts like other masking components, decreasing sensitivity to nearby test frequencies and thereby producing the insensitivity to low spatial frequencies that gives the contrast sensitivity curve its band-pass shape at high light levels. Treating light adaptation as masking by the zero frequency component leads to a general model that describes visual sensitivity to test gratings of varying spatial frequency at varying mean luminance, in the presence (or absence) of masking gratings of varying spatial frequency. Individual components of the model provide insight into visual processing at the system level.
刺激视觉系统往往会使其对某些刺激特性不敏感。这种不敏感通常被称为适应或掩蔽，但两者之间的区别并不明确。光引起的非特异性不敏感通常被视为适应，而模式特异性不敏感则通常被认为是掩蔽。在这里，我们通过在空间频率域中处理这两种情况，统一了对这种脱敏现象的处理。刺激中适应光的量在空间频率域中由零频率分量表示。为了确定这种适应光在空间频率域中是否与其他分量的作用相同，我们比较了零频率分量的掩蔽效应与其他频率分量的掩蔽效应。我们表明，零频率分量的作用与其他掩蔽分量相同，降低了对附近测试频率的敏感性，从而导致在高光水平下对低空间频率不敏感，使对比度敏感性曲线呈现带通形状。将光适应视为由零频率分量进行掩蔽，会得到一个通用模型，该模型描述了在存在（或不存在）不同空间频率的掩蔽光栅的情况下，视觉对不同空间频率的测试光栅在不同平均亮度下的敏感性。该模型的各个分量为系统层面的视觉处理提供了见解。
