In sum, the color red, specifically, does not trigger bulls. Rather, movement and the threat of the matador's presence sends bulls into a fight-or-flight response, causing them to attack.

Bulls, along with all other cattle, are color-blind to red. Thus, the bull is likely irritated not by the muleta ’s color, but by the cape’s movement as the matador whips it around. In support of this is the fact that a bull charges the matador’s other cape — the larger capote — with equal fury.

Many people believe that bulls charge at the color red due to some deep-rooted animosity. However, the truth behind this myth is quite different. Contrary to popular belief, bulls are actually color-blind to red. So, why do bulls charge at matadors waving red capes? The answer lies in their response to movement rather than color.

In summary, bulls see red as a shade of green but have an instinctive aggressive reaction to the color red due to its association with blood and danger. Bullfighters and rodeo personnel use red items to take advantage of this natural reaction in bulls. However, bull temperament also depends on genetics, environment and experience.