Do Dogs See in Colour?

There is a widespread belief that dogs see the world in black and white. In fact this belief is not quite true.

The human eye is set to see most clearly in daylight. Dogs’ eyes, like those of many predators, are set to see most clearly in dim light.

The retina (nerve layer) of the eye contains “rod” cells, which see in dim light and are sensitive to movement, and cone cells, which are sensitive to colour and detail. The human retina has 3 kinds of cone cell, whereas the dog retina has only 2. As a result, dogs see like a colour-blind person who cannot tell red and green apart. Contrary to the common belief — which is also held about colour-blind people — dogs do not see the world in black and white; they simply cannot tell red and green apart.

Because their eyes are on either side of the face, dogs have a visual field of 240 degrees, compared with 200 degrees to the sides in humans. Cats and dogs have a layer beneath the retina called the “tapetum”, which acts as a mirror for incoming light and helps them see more clearly when hunting at night. This is why animals’ eyes shine in car headlights.