Faces of glory: the left-cheek posing bias for medallists of Brazilian jiu-jitsu competitions.

Laboratory studies have shown that people tend to show the left side of their face when asked to broadly express emotions, while they tend to show the right side when asked to hide emotions. Because emotions are expressed more intensely in the left side of the face, it is hypothesized that an individual's intention to express or hide emotions biases the direction of lateral facial poses. The present study tested this hypothesis using photographic portraits of individuals experiencing emotional events in a naturalistic setting: the reception of medals in Brazilian jiu-jitsu competitions. Portrait photographs of Brazilian jiu-jitsu competitors were sourced online (N = 460) and were rated by two independent raters in terms of posing direction, emotional expression, and medal colour. Gold and silver medallists showed their left cheeks to the camera for commemorative photographs taken immediately after the medal ceremony. Positive emotions were expressed more often for gold medallists than silver ones. The left-cheek posing bias observed in the present study supports the hypothesis that the intended purpose of expressing or hiding emotions determines the direction of lateral posing biases, and extends the laboratory findings to situations in the real world.