I know what you're thinking. How can they TELL if cats can see in color? Cats
can't TALK. 

Come on, you think scientists are dummies? One way they test these things is
by figuring out ways to link color to food. 

For instance, suppose you were trying to find out if a cat could tell the
difference between green and gray. You set up two doors. Behind the green
door you put a tasty heap of fish. Behind the gray door you put nothing.

If the cat can see color, eventually he'll learn he's always supposed to open
the green door if he wants to eat. But if he's color-blind, he'll never
learn. He'll push the gray door half the time and the green door the other
half.

Using methods like this, scientists many years ago decided that cats were
color-blind. The cats never seemed to figure out which door they had to push
to get the food.

But other scientists were suspicious. They looked at the retina (REH-tih-nuh)
inside a cat's eye. The retina takes light entering the eye and converts it
into electrical signals that are sent to the brain. (See illustration.)

The retina is made up of thousands of tiny nerve cells. In humans, some of
the cells are cone shaped, and others are rod shaped. (See illustration.)
It's believed the cones detect color during daylight, while the rods detect
light and shadow (that is, black and white) at night.

The thing is, cats have cones in their retinas just like us. Knowing this,
some scientists thought cats might be able to see color if they really tried.

So they retested the cats with fish. After about 10 million tries, the cats
finally got the hang of it. The scientists concluded that cats were
physically able to see color, they just weren't very good at it.

That's probably because cats in the wild hunt mostly at night, when color
vision is of no use to them. For a cat, learning to use color vision is like
learning to knit with your feet. You could do it, but why would you want to?
Cats obviously feel the same way.

Copyright 1993 Chicago Reader