Looking for the perfect smile to impress your friends and co-workers? A new computer program could help. In a new study, researchers created a lifelike human avatar (pictured) and made it smile in dozens of different ways in front of volunteers. It turns out there isn’t one most successful smile, but many within an optimal range, the team reports today in PLOS ONE. The volunteers found slightly asymmetrical smiles more attractive than perfectly symmetrical ones, for example, and favored very wide smiles sporting fewer teeth over wide smiles with many teeth exposed. Researchers expected the volunteers to perceive most smiles as happy ones, but smaller, less curved smiles were seen as contemptuous. The findings could help medical professionals get facial paralysis patients their most successful smiles back.