Mixed martial artists who smile more than their opponents in pre-fight staredowns are more likely to lose the fight, research has found. A smile suggests a level of submissiveness and reduced hostility versus the fighter who does not smile. In fact, the fighter who does not smile might actually perform better if he perceives his opponent as smiling, perhaps giving him a non-verbal sense of his opponent's vulnerability.

The study, "A Winning Smile? Smile Intensity, Physical Dominance and Fighter Performance" by psychologists at the University of Illinois and Cal-Berkley, looked at 152 UFC fighters in 2008 and 2009, comparing their facial expressions during staredowns.

The researchers first had trained coders rate the intensity of the smiles of 152 Mixed Martial Arts fighters in the posed pre-fight photos and then compared these ratings to objective performance statistics from the fight, retrieved from Fightmetric.com. Outcome variables such as effective striking, effective grappling, takedowns and knockouts were analyzed for both fighters. As expected, smile intensity predicted both the outcomes of fights as well as the more detailed measures of in-fight hostility. Interestingly, the smiles predicted both reduced hostility from the smiler as well as increased hostility from his opponent. In other words, it seemed both fighters were attuned to the information being communicated in the pre-fight smile. These results held even when controlling for existing differences in skill (i.e. the betting odds of the fight) and strength (height and weight). Though don't go drastically altering your gambling strategy just yet -the betting line still did a better job overall in predicting fights compared to just smile intensity.

These results were then duplicated by showing the photos to groups of people and asked them to predict who would win. These observers correctly surmised that the fighter who did not smile was more likely to win. An interesting twist was that these photos did not predict future fights, just the one at the moment. Fighters who smiled before one fight mostly lost, while these same fighters were stone-faced the next time and won. It is hypothesized that these fighters' smiles or lack thereof were non-verbal clues as to their confidence level before the fight.

The researchers acknowledge that they could not read minds and that their research isn't foolproof. But keep this study in mind the next time you watch the staredown after a UFC weigh-in.