In experiment 1, blue (b) was the rewarded training colour under white illumination (b_w). The distance in the colour triangle from b_w to the closest colour under the blue illumination is blue-green(bg_b). The distance between b_w and b_b is larger than between b_w and bg_b. In experiment 2, the training colour was yellow, y_w, and under blue illumination lg_b is closer to y_w than y_b. Under the yellow illumination, y_w is closest to y_y and the second closest is yellow-orange (yo_y). In experiment 5, the training colour green was closest to itself under yellow illumination. The closest distance is highlighted in bold.