Colour-coding properties of sustained and transient channels in human vision
Colour-coding properties of sustained and transient channels in human vision
复制标题
人类视觉中持续和瞬态通道的颜色编码特性
作者：
D. Tolhurst
当视觉刺激的颜色在红色和绿色之间反复交替时，所诱发的视觉感受取决于重复的时间频率。在非常低的频率（例如，1-2 Hz）下，颜色的重复变化是显而易见的。但在频率高于10赫兹时，颜色不会发生变化;在这种情况下，刺激会呈现出均匀的黄色，但亮度似乎仍然在闪烁。这种观察表明，刺激的颜色可以通过一组不同于分析亮度或闪烁的通道来分析。闪烁或亮度通道比颜色通道响应更高的闪烁时间频率。这一想法得到了King-Smith的证实，他描述了对彩色闪光的敏感度如何随闪光持续时间而变化。他进一步描述了闪光的主观外观，并得出结论，刺激不一定是由检测其颜色的相同通道检测到的。当闪光短暂时，刺激通常看起来是消色差的，除了当波长低于约490 nm时。闪光的强度必须提高到检测阈值以上，才能感知到颜色。在较长的闪光持续时间，颜色是明显的，只要闪光是可检测的。传递刺激颜色信号的通道比传递无色信号的通道有更长的“整合时间”。这种实验检查两组通道的高时间频率行为的差异。这是有趣的，以检查低时间频率的行为，以及因为最近的神经生理学研究的猴子的视觉系统利用这种行为在分类神经元2 -5。有些神经元对长时间的静止刺激产生持续的反应，有些神经元对刺激的开始只产生短暂的反应。我在这里展示了人类的颜色通道给出持续的响应，而闪烁或亮度通道给出瞬态响应。
WHEN the colour of a visual stimulus is repetitively alternated between say red and green, the percept evoked depends upon the temporal frequency of repetition. At very low frequencies (for example, 1–2 Hz), the repetitive change in colour is readily apparent. But at frequencies above about 10 Hz, no changes in colour are perceived; the stimulus in this case would appear a uniform yellow but would still seem to be flickering in brightness. Observations of this kind suggest that the colour of a stimulus may be analysed by a set of channels different from that analysing the brightness or flicker. The flicker or brightness channels respond to higher temporal frequencies of flicker than do the colour channels. This idea was confirmed by King-Smith1 who has described how the sensitivity to coloured flashes of light changes with flash duration. He further described the subjective appearance of the flash, and concluded that a stimulus was not necessarily detected by the same channels as those that detected its colour. When the flash was brief, the stimuli usually looked achromatic, except when the wavelength was below about 490 nm. The intensity of the flash had to be raised above the detection threshold before the colour could be perceived. At longer flash durations, the colour was apparent as soon as the flash was detectable. The channels signalling the colour of a stimulus have a longer ‘integration time’ than those giving an achromatic percept. This kind of experiment examines differences in the high temporal frequency behaviour of the two sets of channels. It is of interest to examine the low temporal frequency behaviour as well because recent neuro-physiological investigations of the monkey's visual system make use of this behaviour in classifying neurones2–5. Some neurones give a sustained response to prolonged presentation of a stationary stimulus; others respond only transiently to the stimulus onset. I show here that human colour channels give sustained responses while the flicker or brightness channels give transient responses.