Contrary to popular belief, bulls are not enraged by the color red. In fact, bulls are red-green colorblind. As illustrated by MythBusters, whether the cape used in bullfighting is red or any other color, the bull doesn’t react differently. What gets them to charge aggressively is actually the movement of the cape, not the color. The myth that the color red enrages bulls likely stems from matadors traditionally using red capes going all the way back to the 18th century in Spain.