Red is associated with dominance in a number of animal species. For example, in mandrills, red coloration of the face is greatest in alpha males, increasingly less prominent in lower ranking subordinates, and directly correlated with levels of testosterone. Red can also affect the perception of dominance by others, leading to significant differences in mortality, reproductive success and parental investment between individuals displaying red and those not. In humans, wearing red has been linked with increased performance in competitions, including professional sport and multiplayer video games. Controlled tests have demonstrated that wearing red does not increase performance or levels of testosterone during exercise, so the effect is likely to be produced by perceived rather than actual performance. Judges of tae kwon do have been shown to favor competitors wearing red protective gear over blue, and, when asked, a significant majority of people say that red abstract shapes are more "dominant", "aggressive", and "likely to win a physical competition" than blue shapes. In contrast to its positive effect in physical competition and dominance behavior, exposure to red decreases performance in cognitive tasks and elicits aversion in psychological tests where subjects are placed in an "achievement" context (e. g. taking an IQ test).