REVERSED EFFECT OF ADAPTING STIMULI ON VISUAL SENSITIVITY
REVERSED EFFECT OF ADAPTING STIMULI ON VISUAL SENSITIVITY
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DOI：
10.1098/rspb.1980.0131
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发表时间：
1980-01-01
期刊：
影响因子：
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通讯作者：
MOLLON, JD
中科院分区：
文献类型：
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作者：
POLDEN, PG;MOLLON, JD
眼睛对递增刺激的敏感度通常随着稳定的背景场强度的增加而降低。在这里，我们研究了一系列条件，在这些条件下，附加场异常地增加了灵敏度。如果紫光(A=423 nm)测试闪光的阈值强度是在109.7量子S-1°-2的蓝色(μ1=473 nm)场上测量的，那么如果将增强强度的黄色(μ2=575 nm)场添加到背景中，阈值可能会下降0.3-0.4个对数单位。无论是使用是/否还是强迫选择程序，易化都会发生(实验1、2)，当蓝、黄场被区分呈现时(实验5)，易化被取消(实验5)，并且其大小随暴露在复合适应场中的时间而变化(实验6)。最大促进所需的黄场强度(A)随着蓝场强度的增加而增加，(B)通常是使复合场消色所需的强度(实验1、3)。结果表明，心理生理定义的蓝色机制的敏感性不仅仅受短波长感受器吸收的光子控制。我们假设起源于短波长感受器的信号仅限于反色通道(假设1)，并且任何反色通道在其响应范围的中间值时对输入扰动最敏感(假设6)。我们将后一种原理与颜色辨别的线元分析联系起来。μ2的变化使我们能够估计输入到假定的对方通道的长波长输入的作用谱(实验4)。此光谱类似于光度函数V；，但对于μ1>；600 nm，促进作用小于对μ1？575 nm。我们讨论了本研究结果对斯泰尔斯的π机制的影响。如果探测是由对方通道进行的，斯泰尔斯的场敏感度是否会被当场波长改变或添加辅助场时接收后敏感度的变化所污染？尽管事后看来，斯泰尔斯使用的大而长的目标会有利于对手通道的检测，但双色法的一个未被认识到的优势可能是，单色场使对手通道变得不敏感，并确保检测是通过(后接收)灵敏度在场敏感性测量过程中变化很小的非对手通路进行的。斯泰尔斯自己的检查和其他证据表明，π4和π5几乎不会被对手过程扭曲，甚至对于蓝色机制来说，使用长波辅助场可能会调制对手通道的灵敏度，μ<；500 nm的相对场敏感度可能是受体的灵敏度。目前的结果确实表明，斯泰尔斯的双色法可以谨慎地扩展到视觉系统中颜色对立通道的研究。
The sensitivity of the eye to incremental stimuli normally decreases as the intensity of a steady background field increases. We examine here a range of conditions under which an added field anomalouslyincreasessensitivity. If the threshold intensity for violet (A = 423 nm) test flashes is measured on a blue (μ1= 473 nm ) field of 109.7quanta s-1deg-2and if then yellow (μ2= 575 nm) fields of increasing intensity are added to the background the threshold may fall by 0.3—0.4 logarithmic unit. The facilitation occurs whether yes/no or forced-choice procedures are used (experiments 1, 2), is abolished when the blue and yellow fields are presented dichoptically (experiment 5) and varies in magnitude with the duration of exposure to the composite adapting field (experiment 6). The intensity of the yellow field required for maximal facilitation (a) increases as the intensity of the blue field increases and (b) is typically that intensity required to render the composite field achromatic (experiments 1, 3). The results imply that the sensitivity of the psychophysically defined blue mechanism is not controlled merely by photons absorbed in the shortwavelength receptors. We hypothesize that signals originating in the short-wavelength receptors are confined to opponent-colour channels (assumption 1) and that any opponent-colour channel is most sensitive to input perturbations when at an intermediate value of its response range (assumption 6). We relate the latter principle to line-element analyses of colour discrimination. Variation of μ2allows us to estimate the action spectrum of the longwavelength input to the putative opponent channel (experiment 4). This spectrum resembles the photopic luminosity function, V; but for μ1> 600 nm the facilitation is less than for μ1« 575 nm. We discuss the implications of the present results for the π mechanisms of Stiles. If detection were by opponent channels, might Stiles’s field sensitivities be contaminated by variation in post-receptoral sensitivity when field wavelength was varied or when an auxiliary field was added? Although hindsight does suggest that the large and long targets used by Stiles would favour detection by opponent channels, an unappreciated advantage of the two-colour method may be that the monochromatic field desensitizes opponent channels and ensures that detection is via a nonopponent pathw ay whose (post-receptoral) sensitivity varies little in the course of field-sensitivity m easurem ents. Stiles’s own checks and other evidence suggest that π4and π5are little distorted by opponent processes and even for the blue mechanism, where the use of long-wavelength auxiliary fields would be likely to modulate the sensitivity of opponent channels, the relative field sensitivity for μ < 500 nm is probably that of the receptors. The present results do suggest that Stiles’s two-colour method can, with care, be extended to the study of chromatically opponent channels in the visual system.