A new study shows that dogs walking freely on Indian streets have a strong preference for yellow objects.

Dogs see colors differently than humans because they have less color-sensitive cone cells in their eyes. Humans have three types of cone cells that allow us to see different colors. In dogs, these cells are only two types, making it difficult to distinguish colors. 

Dogs see blue and yellow shades clearly, but fail to distinguish shades of red, green and orange, which appear to them as yellow or gray tones, the Independent reported.

Now, researchers at the Indian Institute of Science Education and Research in Kolkata say dogs have a preference for yellow hues.

This could be due to the fact that yellow stands out clearly in their vision.

The research, published recently in the journal Animal Cognition, suggests that this preference for yellow is so strong because it probably arose when dogs evolved from wolves.

Scientists analysed over 130 street dogs in the Indian city of Kolkata. Each was faced with yellow, blue or grey food bowls placed on the ground. 

Most of the dogs headed straight for the yellow bowl, significantly more than the blue or gray. "Even when there was food in the gray bowl and not in the yellow bowl," the researchers emphasized.

"This preference is so strong that it shifts their attraction to food, whether it's biscuit or chicken. Together, these results lead us to conclude that the observed preference for yellow is the result of an attraction to yellow," the study notes.

"We don't yet know exactly what causes this strong preference for yellow," it adds, but it rules out the behaviour being due to a "repulsion to other colours".

Scientists suspect that one reason for the preference may be that most street dogs have coats with orange or brown hues that appear yellowish to other dogs.

Because color preferences can be genetic or acquired, the researchers call for future experiments to test whether this trait is innate.

"Comparative studies with dogs and wolves may help to understand the evolutionary trajectory of this preference for yellow," they say.

Since previous studies in Morocco have not indicated any color preference in dogs, the researchers suspect the findings may be typical of Indian dogs. | BGNES