Burr D C, Fiorentini A, Morrone C
Istituto di Neurofisiologia del CNR, Pisa, Italy.
Vision Res. 1998 Dec;38(23):3681-90. doi: 10.1016/s0042-6989(98)00056-x.
We measured reaction times for detecting motion onset for sinusoidal gratings whose contrast was modulated in either luminance or chromaticity, for various drift rates and contrasts. In general, reaction times to chromatic gratings were slower than to luminance gratings of matched cone contrast, but the difference in response depended critically on both contrast and speed. At high image speeds there was virtually no difference, whereas at low speeds, the difference was pronounced, especially at low contrasts. At high image speeds there was little dependence of reaction times on contrast (for either luminance or colour), whereas at low speeds the dependence was greater, particularly for chromatic stimuli. This pattern of results is reminiscent of those found for apparent speed of drifting luminance and chromatic gratings. We verified the effects of contrast on perceived speed, and went on to show that the effects of contrast on reaction times are totally predictable by the perceived speed of the stimuli, as if it were perceived rather than physical speed that determined reaction times. Our results support that idea of separate systems for fast and slow motion (with separate channels for luminance and colour at slower speeds), and further suggest that apparent speed and reaction times may be determined at a similar stage of motion analysis.
我们测量了在不同漂移速率和对比度下，检测正弦光栅运动起始的反应时间，这些光栅的对比度在亮度或色度上进行调制。一般来说，对彩色光栅的反应时间比对具有匹配锥体对比度的亮度光栅的反应时间要慢，但反应差异关键取决于对比度和速度。在高图像速度下，实际上没有差异，而在低速度下，差异很明显，尤其是在低对比度时。在高图像速度下，反应时间对对比度（无论是亮度还是颜色）的依赖性很小，而在低速度下，依赖性更大，特别是对于彩色刺激。这种结果模式让人想起在漂移的亮度和彩色光栅的视在速度中发现的情况。我们验证了对比度对视在速度的影响，并进而表明对比度对反应时间的影响完全可以通过刺激的视在速度来预测，就好像是视在速度而非物理速度决定了反应时间。我们的结果支持了快慢运动有独立系统的观点（在较慢速度下亮度和颜色有独立通道），并进一步表明视在速度和反应时间可能在运动分析的相似阶段被确定。
