Table 1.

Contrasts (mean±s.e.) between the chromatic colour component and the achromatic brightness component of artificial moths and birch and moss backgrounds. (Note that blue moths were tested separately and therefore not compared with other moth types. Achromatic values of 1.0 predict equal brightness of moths and background.)

moth type	chromatic		achromatic
contrast	statistics	contrasts	statistics
birch
pink	0.42±0.03	pink versus brown: p=0.76	1.0±0.14	pink versus brown: p=0.95
brown	0.40±0.03	cryptic versus pink & brown: p<0.001	0.9±0.13	pink versus cryptic: p=0.84
cryptic	0.29±0.02		0.7±0.10	brown versus cryptic: p=0.67
blue	0.63±0.01		1.0±0.14
moss
pink	0.51±0.02	pink versus brown: p=0.78	2.6±0.16	pink versus brown: p=0.67
brown	0.48±0.02	pink versus cryptic: p=0.83	2.4±0.15	pink versus cryptic: p=0.09
cryptic	0.54±0.03	brown versus cryptic: p=0.43	2.0±0.12	brown versus cryptic: p<0.05
blue	0.56±0.00		2.7±0.17