New Study Shows That Dogs Use Color Vision After All

[The Straight Story]

The idea that dogs only see the world in black, white and shades of gray is a common misconception. What’s true, though, is that like most mammals, dogs only have two types of color receptors (commonly called “cones”) in their eyes, unlike humans, who have three.

Each of these cones is sensitive to a different wavelength (i.e. color) of light. By detecting different quantities of each wavelength and combining them, our three cones can transmit various signals for all the hues of the color wheel, the same way the three primary colors can be mixed in different amounts to do the same.

But because they only have two cones, dogs’ ability to see color is indeed quite limited compared to ours (a rough comparison would be the vision of humans with red-green colorblindness, since they, too, only have two cones). Whereas a human with full color vision sees red, orange, yellow, green, blue and violet along the spectrum of visible light, a dog sees grayish brown, dark yellow, light yellow, grayish yellow, light blue and dark blue, respectively—essentially, different combinations of the same two colors, yellow and blue:

Consequently, researchers have long believed that dogs seldom rely on colors to discriminate between objects, instead looking solely at items’ darkness or brightness to do so. But a new experiment indicates that this idea, too, is a misconception.

As described in a paper published yesterday in the Proceedings of the Royal Society B, a team of Russian researchers recently found that, at least among a small group of eight dogs, the animals were much more likely to recognize a piece of paper by its color than its brightness level—suggesting that your dog might be aware of some of the colors of everyday objects after all.

http://blogs.smithsonianmag.com/science/2013/07/new-study-shows-that-dogs-use-color-vision-after-all/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+smithsonianmag%2FSurprisingScience+%28Surprising+Science+|+Smithsonian.com%29

[hlthe2b]

1. That they only see combinations of yellow and blue is well known... That they recognize "shades"

along this spectrum should not be a surprise.... I truly don't know who they are quoting as having concluded that dogs were using only "light versus dark," but that is not something I've ever seen espoused.

[Lionel Mandrake]

2. This is old news.

I don't believe that "researchers have long believed that dogs seldom rely on colors to discriminate between objects, instead looking solely at items’ darkness or brightness to do so". Who are these researchers? I have studied color vision in some detail and have never seen a peer-reviewed article spouting such nonsense.

Color vision evolved for a reason. It enhances fitness. It works best in bright light, and is therefore most important in mammals that are active in the daytime. It is less important for nocturnal animals.

Trichromacy evolved about 40 million years ago for old-world monkeys and apes (including humans). It has since evolved independently for some but not all new world monkeys. This would not have happened had it conferred no advantage.