Imagine you’re walking down a busy street in India. You see street dogs sniffing around piles of garbage, scavenging for scraps, as they do in many other cities. But what if I told you that color plays a key role in their strategy? In fact, some of these dogs would skip a juicy piece of chicken or a tasty biscuit if there was something else nearby — a plain yellow bowl.
It sounds strange, but researchers from the Indian Institute of Science Education and Research in Kolkata recently published a study suggesting that dogs have a strong preference for the color yellow. In fact, the preference is so strong that researchers suspect it could be something that evolved back in wolves.
Dogs see color differently from humans. Their eyes have fewer types of color-sensitive cells, known as cones, which means they see fewer colors than us. While humans have three types of cones allowing us to perceive a broad spectrum including reds, greens, and blues, dogs have just two types, making their vision similar to that of a person who is red-green colorblind. This means dogs primarily distinguish between shades of blue and yellow, but reds, oranges, and greens appear as muted tones of yellow or gray.
Their simplified color perception means that while they can’t fully grasp some of the vibrant reds and greens that humans see, colors like yellow stand out vividly in their world.
But there could be something else at play.
A strong preference
When researchers conducted experiments with 134 free-ranging dogs, each dog faced a choice: yellow, blue, or gray bowls placed on the ground. Each dog got just one chance to choose. Remarkably, the majority of these street-savvy dogs didn’t hesitate — they headed straight for the yellow bowl, significantly more than blue or gray.
Out of 134 dogs, 72 picked yellow, making it a clear favorite. Researchers repeated the test without food and found the results consistent: dogs showed no hesitation in choosing yellow over the other colors.
This was more than a casual preference — it was a strong and clear attraction to the color yellow, something previously unreported in untrained, street-living dogs.
But researchers didn’t stop there.
Color over food
To test just how powerful this preference was, they presented the dogs with another, more challenging choice. This time, dogs had to choose between a gray bowl with food (either biscuits or chicken) and an empty yellow bowl. Logic says a hungry street dog should pick food every time, but this wasn’t the case.
Most dogs seemed to be more intrigued by the yellow than the food. Out of 52 dogs given a biscuit versus an empty yellow bowl, 41 picked the yellow bowl. Even when the stakes were raised with a more desirable snack — raw chicken — the results hardly changed. Out of 61 dogs tested with chicken, 47 still chose the empty yellow bowl. Clearly, for these dogs, the attraction to yellow was stronger than their drive to eat.
Researchers tried to see whether smell also plays a role. They cleverly tested this theory by covering painted bowls so dogs could smell but not see the color. When they did this, the dogs showed no clear preference, proving their choices weren’t driven by scent. It was all about seeing that vibrant yellow.
What causes this attraction to yellow?
Scientists have several theories. One relates to something called “ecological valence,” where animals prefer colors associated with beneficial or essential resources. To a dog, yellow might signal something valuable — food, safety, or comfort. This could be linked to something specific to this Indian environment, but it could also be something that happened in their evolutionary history before dogs were even domesticated.
“For Indian free-ranging dogs, most of the food available to them is of human origin. Indians often use turmeric (yellow) and dried chili (red) in their food (personal observation), both of which will appear yellow to dogs. Even raw meat (pink) and blood (red) will
appear yellowish,” write the study authors, led by Anamitra Roy, from the Indian Institute of Science Education & Research (IISER). “If this argument holds, this preference for yellow might predate domestication and be reflected in modern wolves who are the closest relatives to dogs. It is important, however, to remember that while scavenging, a dog that is looking for yellow food will come across many false positives: yellow, red, and green human-generated inedible trash.”
Interestingly, this preference for yellow isn’t about rejecting other colors. When the scientists tested just blue versus gray, the dogs showed no clear preference, indicating their reaction wasn’t negative towards other colors but strongly positive towards yellow.
Previously, studies on dogs’ color preferences focused mainly on pets, using intensive training to understand what dogs can perceive visually. The Kolkata study is groundbreaking precisely because it involved dogs living freely in urban environments without prior training or conditioning.
Yellow for your pets?
These findings could have important implications for pet dog owners as well. Could your pet dog also prefer yellow? Would yellow bowls or toys be more appealing to them? It’s not clear yet, but it’s highly plausible that your pet at home shares this strong visual preference with its street-dwelling cousins. Even pet rescue or trapping equipment could be more effectively designed if we understand how dogs react to colors instinctively.
Future research might include comparative studies involving wolves, pet dogs, and street dogs from different regions worldwide. Such research could illuminate the evolutionary origin of this strong color preference. It might also explore whether similar preferences occur in other animals, broadening our understanding of animal cognition and the evolutionary role of color vision.
The study was published in Animal Cognition.
