Why football players wearing red are more likely to see red for bad tackles Scientists asked football referees to watch 52 clips of tackles The tackling player's kit changed to look red, blue, green or yellow Referees were then asked to judge the roughness of the tackle Football players who wear red kit are more likely to be punished for bad tackles by referees, a study has found. Scientists asked experienced football referees to watch 52 clips showing tackles made in the World Cup or in European club games. The tackling player's kit was changed to look red, blue, green or yellow while the opposition player wore white and black. Sent off: Manchester United's Wayne Rooney (right) gesticulates towards referee Phil Dowd (left) after he was sent off for a second bookable offence in 2009 Referees were then asked to judge the roughness of the tackle by pressing a number from one (no foul) to nine (very harsh foul). The study, published in the journal Psychology of Sport and Exercise, found players in red were judged more harshly for tackles from behind than players wearing any other colour. The players wearing blue tops tended to be given the most lenient judgments. The authors at the University of Vienna claimed this is because red is associated in our minds with aggression while blue is linked to 'peace and tranquillity'. Arsenal's Martin Keown sees red and is sent off by Mike Riley against Liverpool Lead researcher Dr Bjoern Krenn said: 'Tackles committed from behind were judged more harshly for players wearing red. Even referees who had a high understanding of the rules showed this tendency.