“Bulls are enraged by the color red”

It’s a persistent image: a matador waving a vibrant red cape, and a charging bull, seemingly incensed by the crimson hue. This dramatic scene, central to the spectacle of bullfighting, has deeply embedded the idea that the color red itself is what enrages bulls. This misconception has been perpetuated for centuries, becoming a widely accepted "fact" in popular culture and even in common idioms.

However, the truth is that the color of the cape is largely irrelevant to the bull's reaction. Bulls, like many other mammals, are dichromatic, meaning they primarily see in shades of yellow, blue, and grey. They are effectively colorblind to red and green. What truly provokes the bull's charge is the movement of the cape, not its specific shade. The matador's skill lies in their ability to skillfully wave and manipulate the cape, creating the motion that triggers the bull's instinctual response to a moving object.

The enduring belief that bulls are enraged by red likely stems from the visual drama of bullfighting. The bright red cape, known as a muleta, serves a practical purpose for the matador in terms of visibility against the arena's backdrop and for concealing bloodstains, but it doesn't possess any special power over the bull. The human eye perceives the striking contrast of the red, leading us to associate the color with the bull's aggression, even though the animal itself is responding to kinetic energy rather than chromatic information.