Does Blue Uniform Color Enhance Winning Probability in Judo Contests?

Abstract

The color of an athlete's uniform may have an effect on psychological functioning and consequently bias the chances of winning contests in sport competition. Several studies reported a winning bias for judo athletes wearing a blue outfit relative to those wearing a white outfit. However, we argue there is no winning bias and that previous studies were confounded and based on small and specific data sets. We tested whether blue biases winning in judo using a very extensive judo data set (45,874 contests from all international judo tournaments between 2008 and 2014). In judo, the first called athlete for the fight used to wear the blue judogi but this was changed to the white judogi in 2011. This switch enabled us to compare the win bias before and after this change to isolate the effect of the color of the judogi. We found a significant win bias for the first called athlete, but this effect was not significantly related to the color of the judogi. The lack of a significant win effect of judogi color suggests that blue does not bias winning in judo, and that the blue-white pairing ensures an equal level of play. Our study shows the importance of thoroughly considering alternative explanations and using extensive datasets in color research in sports and psychology.

Perceiving speed—The color can matter

“…With regard to the other sport-related performance parameters, no color effects were found for force, posture, dynamics, ergonomics, and fitness. These null findings are in line with previous results from color research in sport, 7,10,11,21,42 which suggests that we should also entertain the possibility that colors do not influence specific parameters in certain contexts. 15 That a color effect was observed for speed perception but not the other sportrelated parameters could be due to the fact that speed is easier to perceive and interpret compared to more ambiguous parameters, such as ergonomics or fitness.…”

Commentary: Does Blue Uniform Color Enhance Winning Probability in Judo Contests?

“…The commented paper Dijkstra et al ( 2018 ) is an exhaustive work which sheds light on the role of the white and blue judogi (judo outfit) in judo contests. The importance of colored uniforms has been proven in other sports (i.e., Attrill et al, 2008 ; Falcó et al, 2016 ; Krenn et al, 2017 ).…”

“…The results of these studies were negatively affected by the small number of contests analyzed (400–1,600) and also by the seeding effect. Dijkstra et al ( 2018 ) have solved this uncertainty by analyzing more than 42,000 contests, making their conclusions statistically representative. According to Dijkstra et al ( 2018 ), there is a bias toward the “first called athlete,” who has a greater chance of winning the match, especially from the sixteenth (1/16) round.…”

“…Dijkstra et al ( 2018 ) have solved this uncertainty by analyzing more than 42,000 contests, making their conclusions statistically representative. According to Dijkstra et al ( 2018 ), there is a bias toward the “first called athlete,” who has a greater chance of winning the match, especially from the sixteenth (1/16) round. This “first called athlete” bias is independent of the judogi color.…”

“…In both cases the bias favored the first called athlete. For Dijkstra et al ( 2018 ) this bias would be due to factors like seeding, skill of the athletes, or even intercontest intervals. However, we have two remarks that are intended to complement the conclusions of Dijkstra et al ( 2018 ).…”