Figure 2.

Choice frequencies (with 5% confidence intervals) of M. stellatarum trained to discriminate a dimmer (grey bars) from a brighter (white bars) light of 440 nm. (a) Control test after six days of training, 130 choices by 13 animals, G-test, p<0.001. (b) The dim light is chosen even if it has changed wavelength, 470 nm; 130 choices by 13 animals, G-test, p<0.005. (c) Test for relative intensity learning, black bars indicate choices for a light 10 times dimmer than the positive training intensity (grey bars); 110 choices by 11 animals, G-test, n.s.