Superior discrimination for hue than for saturation and an explanation in terms of correlated neural noise

The precision of human colour discrimination depends on the region of colour space in which measurements are made and on the direction in which the compared colours—the discriminanda—differ. Working in a MacLeod–Boynton chromaticity diagram scaled so that thresholds at the white point were equal for the two axes, we made measurements at reference points lying on lines that passed at 45° or −45° through the white point. At a given reference chromaticity, we measured thresholds either for saturation (i.e. for discriminanda lying radially along the line passing through the white point) or for hue (i.e. for discriminanda lying on a tangent of a circle passing through the reference point and centred on the white point). The discriminanda always straddled the reference point in chromaticity. The attraction of this arrangement is that the two thresholds can be expressed in common units. All that differs between saturation and hue measurements is the phase with which the short-wave signal is co...人类色彩辨别精度取决于测量所在的色彩空间区域，以及待比较颜色（即辨别刺激discriminanda）的差异方向。本研究采用经缩放处理的麦克劳德-博伊顿色度图（MacLeod–Boynton chromaticity diagram），使白点（white point）处两个轴的阈值保持一致。我们在穿过白点且呈45°或−45°夹角的直线上的参考点处开展测量。在给定参考色度下，我们要么测量饱和度阈值（即待辨别刺激沿穿过白点的径向分布），要么测量色调阈值（即待辨别刺激位于以白点为圆心、过该参考点的圆的切线上）。所有待辨别刺激的色度始终横跨该参考点。该实验设置的优势在于，两类阈值可采用统一单位进行表述，饱和度与色调测量的唯一差异仅在于短波信号的相位……