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Reverse-engineering a winning smile

Researchers from the University of Minnesota have figured out the features of a winning smile.

  • It's a balance of the mouth's angle, smile width, how many teeth are visible and symmetry. Best bet: showing just a little bit of teeth.
  • Smiles that form slightly asymmetrically were seen as more "genuine" and "pleasant" — to a point. If it happens relatively slowly (longer than 125 milliseconds), the crooked smile just starts to get "creepy."

Why the findings matter:

  • They guide surgeries to reanimate someone's face after a stroke, says author Sofia Lyford-Pike, a facial plastic and reconstructive surgeon at the University of Minnesota. (People who are unable to smile effectively are at increased risk for depression.)
  • It could inform computer graphics.
  • More broadly, the work may help to understand how individual differences in facial expressions can lead to differences in how people perceive threats, trustworthiness and other socially relevant cues, something researchers have long studied.