Stromeyer C F, Lee J, Eskew R T
Division of Applied Sciences, Harvard University, Cambridge, MA 02138.
Vision Res. 1992 Oct;32(10):1865-73. doi: 10.1016/0042-6989(92)90047-m.
Thresholds of luminance and red-green chromatic flashes (200 msec) were measured on a yellow adapting field in the fovea and periphery (up to 12 degrees eccentricity for 1 degree flashes and 21 degrees eccentricity for 2 degrees flashes). Chromatic sensitivity (in cone contrast coordinates) is about 7 times higher than luminance sensitivity in the fovea but falls faster with eccentricity, so that luminance and chromatic sensitivities are similar at eccentricities of 20 degrees or less. At eccentricities greater than about 14 degrees, there is a clear asymmetry wherein green chromatic flashes are considerably less detectable than red ones. By measuring complete detection contours for many ratios of incremental and decremental red and green flashes, we isolated the red and green chromatic detection mechanisms, and demonstrated that the red-green asymmetry is not a property of the L- or M-cone response per se, but rather is a property of the post-receptoral, chromatic mechanisms. The peripheral luminance and chromatic mechanisms could be further separated with a suprathreshold luminance flash (a pedestal), since an intense pedestal masks coincident luminance test flashes but facilitates the chromatic flashes. The luminance pedestal approximately linearizes the chromatic detection function (the psychometric function).
在黄斑中心凹和周边区域的黄色适应背景下，测量了亮度阈值以及红-绿彩色闪光（200毫秒）的阈值（对于1度闪光，偏心度最高可达12度；对于2度闪光，偏心度最高可达21度）。在黄斑中心凹，彩色敏感度（以视锥细胞对比度坐标表示）比亮度敏感度高约7倍，但随着偏心度增加下降得更快，因此在偏心度为20度或更小的情况下，亮度和彩色敏感度相似。在偏心度大于约14度时，存在明显的不对称性，即绿色彩色闪光比红色闪光的可检测性明显更低。通过测量许多递增和递减红、绿闪光比例下的完整检测轮廓，我们分离出了红、绿彩色检测机制，并证明红-绿不对称性并非L或M视锥细胞反应本身的特性，而是感受器后彩色机制的特性。由于高强度的基座会掩盖同时出现的亮度测试闪光，但会促进彩色闪光，因此可以用阈上亮度闪光（一个基座）进一步分离周边亮度和彩色机制。亮度基座使彩色检测函数（心理测量函数）大致呈线性。
