[I]n 1915 at the University of Colorado, two scientists were trying to determine whether cats could see colors and so devised an experiment like so: two jars, one wrapped with gray paper, one wrapped with colored paper, were placed before the cat.
If the cat touched the colored jar with its nose or paw or the like, it would get a tiny fish. If it touched the gray jar, it got nothing. After 18 months and 100,000 tries, the cats tested only correctly picked the colored jar around half the time.
However, cats did have both cones and rods in their eyes, which seemed to fly in the face of the above research. [U]using electrodes, neurologists wired up a cat’s brain and showed the cat various shades of color. What they found was that the cat’s brain did respond and distinguished between many shades of color.
After it was discovered that cats could distinguish colors, the “fish” style experiment was run again in the 1960s. This time, it was a success. However, cats never learn this trick very quickly. On average, it took about 1550 tries before each cat would finally learn to pick the colored item to get their treat.
So why did it take the cats so long to learn the trick?
The most likely reason is that unlike humans, for whom color differentiation was a critical survival skill (don’t eat that “fruit” or you might die…), color is pretty unimportant generally for cats.
Or maybe they were just messing with the researchers. They are cats, after all.
Neither cats nor dogs can see color as well as humans can, still; cats cannot see red at all, and dogs have a great deal of trouble differentiating between red and orange. Both are much better at seeing in low-light conditions than humans, of course.