WASHINGTON, August 11, 2008 (AFP) - If three German psychologists have it right, the crimson-clad Chinese team has all the advantage in the Olympics: they found that sports referees have a distinct bias for competitors in red uniforms.

In research on referees of tae kwon do matches, Norbert Hagemann, Bernd Strauss and Jan Leibing of the University of Munster found evidence that the color of a uniform can affect the split-second decisions a referee has to make, and lead to possible bias in scoring.

The three tested referees on videos of tae kwon do matches which pitted one competitor in red against another in blue.

For 42 matches the referees assigned points to the competitors.

And then the psychologists showed the referees a second set of matches -- in fact the same matches, but with the colors of the competitors digitally reversed.

They discovered that overall red-clad competitors earned an average 13 percent more points that those in blue -- even though each athlete appeared in both red and blue at different times.

'What's more, points awarded seemed to increase after the blue athlete was digitally transformed into a red athlete and decrease when the red competitor changed to blue,' the researchers said in a summary.

'Referees decisions will 'tip the scales' when athletes are relatively well-matched but have relatively small influence when one is clearly superior,' they said.

The psychologists said more research is needed to test other colors, but added their conclusions suggest a need to change competition rules or use more electronic decision-making aids in some sports where the color bias could be a problem.