Attribution to red suggests special role in dominance signalling

In many animals red is a signal of dominance and in humans there is evidence that red colouration may provide an advantage in sporting competition. This has been disputed by findings showing that colours other than red can also provide a competitive advantage. Here we examine basic perception of red versus blue in simple shapes by human judges to address the social signalling properties of red. We show that red is seen as more likely to win in physical competitions, more aggressive and more dominant then blue. When hue information is removed, however, the darker contrast of the blue shapes leads to a reversal in the attributions. This confirms that red hue is special in social attribution consistent with it being a signal of competitive quality and that darker contrast, through a potential link to testosterone signalling, could also act as a signal of dominance.