Cole G R, Stromeyer C F, Kronauer R E
Division of Applied Sciences, Harvard University, Cambridge, Massachusetts 02138.
J Opt Soc Am A. 1990 Jan;7(1):128-40. doi: 10.1364/josaa.7.000128.
The visibility of a 1 degree, 200-msec flash on a large yellow field was measured as a function of the intensity of a coincident pedestal flash (a flash that was the same in both temporal intervals of a two-alternative forced-choice trial). The various flashes were incremental (+Lum) or decremental (-Lum) yellow luminance flashes or green (+Chr) or red (-Chr) isoluminant chromatic flashes. With uncrossed conditions (Lum tests on Lum pedestals or Chr tests on Chr pedestals), we obtained the conventional dipper function, that is, the function of threshold test intensity was highly asymmetric about zero pedestal intensity, and strong pedestals induced strong masking. Crossed conditions produced neither effect: for example, with Chr tests on Lum pedestals, there was no dipper function: the function of threshold test intensity was symmetric about zero pedestal intensity, and strong pedestals produced no masking. Instead, the suprathreshold luminance pedestals facilitated chromatic detection by as much as 2-3X and also linearized the chromatic psychometric function, further enhancing sensitivity to weak chromatic stimuli. (Chromatic sensitivity on the suprathreshold luminance pedestal was approximately 25X higher than luminance sensitivity on the uniform field.) A pedestal consisting of a thin luminance ring that surrounded the chromatic test produced facilitation equal to that of the uniform-luminance pedestal: the pedestal may thus act to demarcate the test spatially and promote chromatic comparison with the surround. Removing the uniform yellow surround eliminated this crossed facilitation but did not eliminate the uncrossed facilitation (the dipper function), suggesting that different mechanisms mediate the crossed and uncrossed facilitations.
在一个大的黄色背景上，测量1度、200毫秒闪光的可见度，作为同时出现的背景闪光强度的函数（背景闪光在二选一强制选择试验的两个时间间隔中是相同的）。各种闪光包括增量（+Lum）或减量（-Lum）的黄色亮度闪光，或绿色（+Chr）或红色（-Chr）等亮度的彩色闪光。在不交叉条件下（对亮度背景进行亮度测试或对彩色背景进行彩色测试），我们得到了传统的勺状函数，即阈值测试强度函数关于零背景强度高度不对称，强背景会引起强烈的掩蔽。交叉条件下则没有这些效应：例如，对亮度背景进行彩色测试时，没有勺状函数：阈值测试强度函数关于零背景强度对称，强背景不会产生掩蔽。相反，阈上亮度背景使彩色检测的灵敏度提高了2至3倍，还使彩色心理测量函数线性化，进一步增强了对微弱彩色刺激的敏感性。（阈上亮度背景下的彩色灵敏度比均匀背景下的亮度灵敏度高约25倍。）由围绕彩色测试的细亮度环组成的背景产生的促进作用与均匀亮度背景相同：因此，背景可能起到在空间上划分测试区域并促进与周围环境进行彩色比较的作用。去除均匀的黄色背景消除了这种交叉促进作用，但没有消除不交叉促进作用（勺状函数），这表明不同的机制介导了交叉和不交叉促进作用。
