We apparently evolved to spot people experiencing certain emotions quickly, a phenomenon called the emotional-face-in-a-crowd effect. Some studies indicated that angry-looking people jumped out at onlookers. Other studies said it was happy faces. The conflict may have stemmed from the type, or rather the toothiness, of the angry and happy faces used in the experiments.

 

To clear up the discrepancy, researchers created two facial expressions for each emotion, one with bared teeth and one without. They also created a neutral face. A dozen adults then had to pick out the target emotion from a group of faces. And they did it twice as fast when the target’s teeth were visible. The study thus fills a cavity in our understanding.