Referees try to be fair, but on occasion even the best make bad calls. Now it would seem that sometimes they cannot help it. Researchers reveal that colours worn by competitors can shape referee decisions.
In 2005, evolutionary biologists Russell Hill and Robert Barton at the University of Durham, UK showed that wearing red clothing positively impacted an athlete's performance. They suggested that this was due to an association between red and dominance and/or aggression.
Psychology groups immediately started debating the idea, with some attributing the bias to differences in opponents' visibility. Now Norbert Hagemann and colleagues at the University of Münster, Germany, suggest a different possibility: the colour worn by an athlete might affect the decisions made by referees.
To test their theory, they showed 42 referees of the martial art taekwondo video excerpts from sparring rounds between similarly skilled athletes. In each video, one athlete wore blue protective gear and one wore red (see image, top right).
Each referee individually judged each clip, assigning points for the attacks made. They then watched the same bouts, in a different order, but this time with the colour of the protective gear digitally reversed, so that combatants wearing blue now appeared to wear red, and vice versa (see image, below right).
The team found that referees gave 13% more points to red competitors, even when the performances were exactly the same.
"This is a neat experiment. It reinforces the fact that colour influences the outcome of sporting contests," says Barton. It appears that referees' judgements are also influenced, he says, perhaps by altering their subconscious attributions of dominance in the contest they are observing.
With the Olympics coming up, the find raises questions about how such psychological effects will shape competitions. Boxing, tae kwon do, and wrestling have traditionally used red and blue for competitors and are expected to use them again in Beijing.
Competitors at taekwondo tournaments often wear electronic blow detectors to aid referees, says Hagemann. "But such devices are not used in boxing and still do not alter any psychological benefit granted to athletes merely wearing red."
As for team games, Hagemann expects some minor bias amongst referees, "but the effect should be small compared to a combat sport [where] the outcome is mainly based on several judgments," he says. "In team sports there could be a bias only in ambiguous tackling situations and these are usually rare."