To examine whether fallow deer, Dama dama, have colour vision, we trained f
our adult females on a two-choice discrimination task, where a positive chr
omatic stimulus (green) and a negative achromatic stimulus (grey) had simil
ar brightness. The criterion for learning was set at 80% correct responses.
To exclude the possibility that the hinds used small differences in bright
ness to distinguish between the green and the grey stimulus, we conducted a
test that differed from the training situation. A light green positive sti
mulus combined with a dark grey negative stimulus was alternated with a dar
k green positive stimulus combined with a light grey negative stimulus on e
very second trial. The positive green stimuli had different reflectance spe
ctra. After training, each of the four hinds showed over 80% correct respon
ses in the test. These results suggest that fallow deer can use colour visi
on in a discrimination situation by generalizing over slightly different co
lours, at least in the range of the green spectrum. (C) 2001 The Associatio
n for the Study of Animal Behaviour.