The belief that a bull is enraged by the color red is a classic cultural image, often portraying the matador’s red cape, or muleta, as the trigger for the bull’s aggressive charge. Scientific evidence reveals this popular idea is entirely inaccurate. The animal’s vision and behavioral responses confirm that the charge has little to do with the color red and everything to do with how these animals perceive the world.
How Bulls Perceive Color
The biological reality of a bull’s eyesight fundamentally disproves the red-rage myth. Cattle, including bulls, possess a type of color vision known as dichromacy. Unlike humans, who are trichromatic and have three types of cone cells for perceiving color, bulls have only two types of cone cells in their retinas.
This structure means that a bull’s visual world is limited primarily to the blue and yellow spectrums, classifying them as effectively red-green colorblind. The cone cells responsible for detecting the long wavelengths of light that humans perceive as red are absent in the bovine eye. Consequently, a vibrant red cape does not appear as a striking red hue to the bull, but rather as a shade of yellowish-gray or brown.
The retina contains two types of light-sensitive cells: rods and cones. Rods are responsible for motion detection and night vision, while cones process color. Because bulls lack the cone specialized for red light, they cannot distinguish red from certain shades of green or gray. This physiological limitation confirms that the color itself cannot be the stimulus for an enraged reaction.
The Real Trigger for a Bull’s Charge
The aggression displayed by a bull is not a response to color but is triggered by sudden, erratic movement within its field of vision. Bulls are highly reactive to motion, perceiving any rapid, unpredictable movement as a potential threat requiring defense or attack. This instinctual “fight or flight” response is activated when the matador violently whips the cape.
The bull’s natural temperament, combined with the stressful, unfamiliar environment of the arena, makes it sensitive to visual stimuli. When the matador waves the cape, the resulting large, flapping motion captures the bull’s attention far more than any static object. This movement is interpreted as a challenge or an attack, prompting the animal to charge in an attempt to neutralize the perceived danger.
Evidence supporting this fact lies in the early stages of a bullfight. During these phases, the bull is confronted with a larger cape, the capote, which is typically magenta and gold or blue. Despite not being red, the bull charges the capote with the same fury, proving that the aggressive, whipping action of the cloth provokes the response, not its specific color.
Why the Matador’s Cape is Red
If the color red does not anger the bull, the continued use of a red muleta in the final stage of the bullfight is due to practical and aesthetic reasons for the human audience. The primary, practical function of the red color is to help disguise the blood that is shed during the fight.
The muleta is the final, smaller cloth used just before the killing blow, or estocada. As the bull is often bleeding from prior wounds by this stage, the red fabric is highly effective at concealing the bloodstains from both the bull and the spectators. This keeps the visual spectacle cleaner and less overtly gruesome for the crowd.
Beyond the practical concealment of blood, the red color serves a theatrical purpose, heightening the drama for the audience. Red is a color culturally associated with danger, passion, and excitement, which amplifies the emotional intensity of the final confrontation. The tradition of using the red muleta has persisted because it is a powerful, symbolic prop that appeals to human psychology and the expectations of the historic spectacle.