None of this should come as a great surprise, since the aggressive nature of the colour red has long been known to psychologists, though their findings have never been properly implemented by footballers. In 1939, D Lack, in his paper "The Behaviour of the Robin II" (Proc Zool. Soc London Vol 109) concluded that when a male robin attacks another male robin, it is the redness of the breast that brings out the aggression. His experiments had shown that a male robin will attack a red feather duster, but will not attack a model of a male robin, perfect in every respect except that it did not have a red breast.
Interestingly, if you dye a female chaffinch's underparts red (in imitation of males of the same species) she will win more fights against other females and thus improve her position in the social hierarchy. Red-dyed females will even become a match for males in their group, if they are also denied all male company for four to five weeks.
Niko Tinbergen added to this in 1951 when he pointed out that a male stickleback will react aggressively to red colouring on a rival male, but only if the red is on its belly - not on its back. The ideal strip for a football team might therefore be blue on the front and red on the back - to gain both intellectual and physical superiority.
It's quite different if you are playing squash instead of football. MR Pruitt, in his 1984 dissertation for Tennessee State University, "Effects of selected colours on reaction time and racquetball wall volley performance", examined the effect of different ball colours on the play of individuals of differing standards. The results enabled him to conclude that beginners would do better playing with green and fluorescent orange balls than with blue ones.
None of this, however, totally explains the finds of O Kroh and R Scholl, reported in their 1926 paper "Vergleichende Untersuchungen zur Psychologie der optischen Wahrnehmungsvorgange. II ber die Teilinhaltliche Beachtung von Form beim Haushuhn", when they showed that a chicken will always peck grain on a blue triangle in preference to that on a red circle.
With all this body of information, it may seem surprising that there has been such little interest recently in the Luscher Colour Test. Popular around 1970, the test invited subjects to place eight coloured cards in order of preference. Every detail of the chosen order could then be analysed to reveal minute details of personality. I was once on the point of doing the Luscher test at a dinner party of a psychologist friend, but his wife got to the cards first and put them in her preferred order. We looked up the interpretation and it told us that because she had pink in fifth place and grey in sixth (or some such combination) she "could get physical satisfaction from sexual activity". After that, none of the rest of us dared do the test. In case we didn't have pink in fifth and grey in sixth.