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.

What they did: The researchers created 3D computer animated faces with slightly different smiles constructed from combinations of different angles of the mouth, varying extents of the smile, how much teeth were showing and how symmetrically the smile formed on the face. 802 people were then asked to rate 250 millisecond-long video clips of the smiles forming for their effectiveness, how genuine they seemed, whether they were "pleasant" or "creepy," and what emotion they thought the smile conveyed. The best-rated smiles have lips angled between 13 and 17 degrees and extend between 55% and 62% of the distance between the eye's pupils.

Two smiles with a combination of (a) smaller and (b) larger mouth angle-smile width combination. Increasing how much teeth are visible led to a more favorable rating of the smile in (b) and a worse rating for (a).Helwig et al. University of Minnesota

Limitation: The study only modeled the mouth. Previous work has found the eyes influence people's perceptions but the study shows the mouth can transmit a lot of information on its own, says Lyford-Pike.

What's next: Determining whether the results translate to spontaneous smiles of different, real people, is a key question, says Aleix Martinez, a cognitive scientist and professor of electrical and computer engineering at Ohio State University. Martinez asks: "Can you predict a person's success (personal, profession) on the "niceness" of their smiles?"

Go deeper

Updated 2 hours ago - Politics & Policy

U.S. officials: Iran and Russia aim to interfere in election

Iran and Russia have obtained voter registration information that can be used to undermine confidence in the U.S. election system, Director of National Intelligence John Ratcliffe announced at a press conference Wednesday evening.

Why it matters: The revelation comes roughly two weeks before Election Day. Ratcliffe said Iran has sent threatening emails to Democratic voters this week in states across the U.S. and spread videos claiming that people can vote more than once.

Updated 2 hours ago - Politics & Policy

Coronavirus dashboard

Illustration: Aïda Amer/Axios

  1. Politics: Senate Democrats block vote on McConnell's targeted COVID relief bill McConnell urges White House not to strike stimulus deal before election.
  2. Economy: Why the stimulus delay isn't a crisis (yet).
  3. Health: New York reports most COVID cases since MayStudies show drop in coronavirus death rate — The next wave is gaining steam.
  4. Education: Schools haven't become hotspots — San Francisco public schools likely won't reopen before the end of the year.
  5. World: Spain becomes first nation in Western Europe to exceed 1 million cases.
Updated 3 hours ago - Politics & Policy

Supreme Court blocks Alabama curbside voting measure

Photo: Mark Wilson/Getty Images

The Supreme Court on Wednesday evening blocked a lower court order that would have allowed voters to cast ballots curbside at Alabama polling places on Election Day.

Whit it matters: With less than two weeks until Election Day, the justices voted 5-3 to reinstate the curbside voting ban and overturn a lower court judge's ruling designed to protect people with disabilities during the coronavirus pandemic.