Fig. 5. Red color discrimination. Percent choices of P. icarus for the rewarded yellow, as a function of the ratio between the intensities of the rewarded and the unrewarded color. The number of choices made for each test and intensity ratio is indicated. (A) Choices made by 70 animals in tests with yellow and blue. G-test, P<0.05 for all intensity ratios. (B) Choices made by 86 animals in tests with yellow and red. G-test, P<0.05 for all ratios of intensity except 0.25. Note that the choice frequency for the rewarded color is significantly lower than chance in the test with 0.1 intensity ratio.