The Misconception

It is commonly believed that bulls are enraged by the color red, thus initiating a charge towards the said red object. An example of this is in bullfighting, the Matador uses a red "cape" called a muleta, during the fight with the bull.(5) It is actually the movement, not the color that makes the bull charge. The more movement there is, the more likely it is that the bull will charge.

Cattle have dichromacy, leaving them red-green colorblind and falsifying the misconception that the color red makes them angry; they just respond to the movement the muleta makes.(2) The red coloring is traditional and is believed to both dissimulate blood stains and provide a suitable light-dark contrast against the arena floor.(3)

Where does this Misconception come from?

History: Bullfighting has it's history rooted deep in Europe, but the exact timeline is sketchy. Around the 1130's bullfighting started occurring in public places for spectators.Bullfighting has an on and off history as some Popes and leaders tried to ban it while others enjoyed it. In 1729 there were two prominent men who were both credited with being the founders of Professional Bullfighting, Joaquin Rodriguez Costillares, and Pedro Romero. Pedro is credited with being the first Spanish matador who began using a small red cape, or muleta, in bullfighting during the third and final (death) round in the 1730s.(4) Before this animal skins were used in much the same way as the muleta. People began associating the color red with the bull and the fighting, hence the misconception. Not having the technology to know that cattle can't see the color red, you would normally begin making your own assumptions based off of what you can see and what you knew at that point.

Artists also helped carry this misconception along as well. From Picasso to Degas, there are so many paintings that depict bullfighting and the red muleta is incorporated in the art. Authors also tie bullfighting together with the red cape, one example of this is the book, The Story of Ferdinand, by Munro Leaf. In this story the Matador is depicted with his red cape as well. The cape and it's color are so intertwined it's no wonder this misconception has been around for so long.

MythBusters also busted this myth on their popular show during season 5 episode 18. They "set out to find a way to test this myth — carefully. They decided to put makeshift matadors into an arena, each holding a flag of a different color, and wait for an angry bull to see red.
The red, blue and white flags got equal, half-hearted attacks when they were motionless. In order to elicit an aggressive charge response from the bull, the flags had to be waved.
Turns out, the color red isn't what causes bulls to attack. In fact, bulls don't seem to have any color preference at all. They'll charge whichever object is moving the most, which means this old myth can get tossed right out of the ring."(1)

2. Murphy, J. et al, //What Horses and Humans See: A Comparative Review'//, International Journal of Zoology Volume 2009 (2009), Article ID 721798.
3. Fiske-Harrison, Alexander. Prospect magazine, "A Noble Death". September 2008. Retrieved on 2013-20-4.