|MadSci Network: Zoology|
The answer is yes, I am afraid rats are color blind, but they are as color blind as color blind people, but probably not monochromats (i.e they see colors but their discrimination of color is not as good as that of normal human beings or some insects).
See in Vision:
"Rats and mice have poor vision beyond three or four feet, but they are very sensitive to motion up to 30-50 feet away. They appear to be color blind. However, very light colored or reflective objects may stand out in their environment and cause aviodance among sensitive rodents. Mice are most active at night when light levels are low and rely lesson their eyesight then they do on their other senses, particulary smell and hearing."
Also see a nice introduction on colorblindness to understand what color blindedness means. Click here or here.
"Another essential refinement, COLOR PERCEPTION, also evolved independently several times, although intermittently. Among mammals, only humans, primates, and a few other species can recognize colors. Among insects, honeybees can be trained to distinguish colors, but they are color-blind to red. Similar training experiments have shown that at least some teleost, or bony fish, can discriminate colors, but elasmobranches, such as sharks, cannot."
Reference: Thomas P. Mattingly and Melvin L. Rubin The Eye, Groulier 1995 Encyclopedia
But if you ask if they could differentiate things based on color I think you should read this example: "Dogs have long been mistakenly considered color-blind. While they are unable to differentiate colors ranging from greenish yellow through orange to red, recent studies have shown that they can distinguish between colors at opposing ends of the spectrum."
Reference: Jacob E. Mosier groulier 1995
Alan J. Robertson is one of the world leading persons in COLOR PERCEPTION.
Try the links in the MadSci Library for more information on Zoology.