Flanagan P, Dodwell P C
Department of Psychology, Queen's University, Kingston, Ontario, Canada.
Spat Vis. 1991;5(3):159-87. doi: 10.1163/156856891x00074.
Visual channels are defined psychophysically; stimuli that interact share information in the same channel, and those that do not interact are processed in different channels. Channels are often investigated by means of adaptation to one stimulus, testing contrast threshold elevation with one (or more) others. Much recent work has tested the tuning of channels for orientation and spatial frequency, using simple line gratings. This study examined the pattern-specificity of such adaptation, testing the hypothesis that the fundamental operators of the Lie Transformation Group Theory of Neuropsychology (LTG/NP) define psychophysical channels. In Experiment I the three basic pattern pairs of LTG/NP were used as adaptation and test stimuli in a conventional contrast threshold-elevation experiment. Threshold elevation was pattern-specific, thus supporting the hypothesis. In subsequent experiments various 'fractured' patterns, and patterns generated by combinations of Lie operators were used both for adaptation and test. The results were mixed; some supported the original hypothesis, but many did not. Relations between local contour orientations in adaptation and test patterns could explain some results, but not all. The hypothesis that adaptation occurs to the oriented spatial-frequency components of the test patterns, on the other hand, gave a good fit to the data. It is concluded that there is pattern-specificity in contrast threshold elevation, but it is a form of specificity that can be explained without recourse to a model of geometrical pattern processing, at least for the simple patterns used here.
视觉通道是通过心理物理学来定义的；相互作用的刺激在同一通道中共享信息，而不相互作用的刺激则在不同通道中进行处理。通常通过对一种刺激进行适应，并使用一种（或多种）其他刺激来测试对比度阈值升高的方式来研究通道。最近的许多工作使用简单的线光栅测试了通道对方向和空间频率的调谐。本研究检验了这种适应的模式特异性，验证了神经心理学李变换群理论（LTG/NP）的基本算子定义心理物理通道的假设。在实验一中，LTG/NP的三个基本模式对被用作传统对比度阈值升高实验中的适应刺激和测试刺激。阈值升高具有模式特异性，因此支持了该假设。在随后的实验中，各种“破碎”模式以及由李算子组合生成的模式被用于适应和测试。结果参差不齐；一些支持了原始假设，但许多没有。适应模式和测试模式中局部轮廓方向之间的关系可以解释一些结果，但不是全部。另一方面，关于适应发生在测试模式的定向空间频率成分上的假设与数据拟合得很好。得出的结论是，对比度阈值升高存在模式特异性，但这是一种特异性形式，至少对于这里使用的简单模式来说，可以在不借助几何模式处理模型的情况下得到解释。
