Colorblindness in the rat

Using Devoe''s Poster paints and a modification of Lashley''s jumping apparatus, an attempt was made to train Chinese Hooded rats to distinguish between shades of red, green, blue and gray. The first set of rats reacted easily to brightness differences but failed to distinguish between hues when position habits, smell, and brightness differences were eliminated. Between any two colors presented confusion pairs were easily determined. A 2nd set of rats after much more training than was necessary for the 1st set were unable to differentiate the confusion pairs although were later easily trained to brightness differences. The rats were regarded as being unable to discriminate amongst reds, blues, greens, and grays provided that brightness (and other secondary criteria) had been equalized for the rat''s eye by tests on rats conditioned to brightness differences.