New research shows that less is more when it comes to a successful smile, which could have implications for how surgeons and therapists work with patients who have facial paralysis.
The study published in PLOS ONE observed how 802 people perceived 3D computer-animated facial models that had varying mouth angles, symmetry, extent of smile and amount of showing teeth. Participants were also asked to rate smiles based on effectiveness, genuineness, pleasantness and perceived emotional intent.
“People may think this is merely a vanity test, but it has major implications for how we work with patients that have facial paralysis,” said Sofia Lyford Pike, MD, senior author of the study and assistant professor within the University of Minnesota Medical School. “By knowing how society perceives facial motion and smiles, we can work with our patients to recover in a way that will enhance their interactions with others and improve quality of life.”
The researchers found that a successful smile – one that is rated effective, genuine and pleasant – may contradict the “more is always better” principle because bigger, toothier smiles were not as well perceived. Successful smiles had an optimal balance of teeth, mouth angle and smile extent. Smiles were also rated as more successful if they developed quite symmetrically, with the left and right side of the faces being synced to within 125 milliseconds.
“A lot of people don’t understand how important their smiles are and how important this aspect of communication we do with each other every day is,” said co-author Stephen Guy in an interview with The Guardian. Guy is a faculty member and researcher in the University of Minnesota College of Science and Engineering.
Facial cues are an important form of nonverbal communication in social interactions, and previous studies indicate that computer-generated facial models can be useful for systematically studying how changes in expression over space and time affect how people read faces.
Co-author and University of Minnesota Department of Psychology researcher Nathaniel Helwig told ResearchGate:“Partial facial paralysis robs an individual of their ability to smile, which can have significant psychological and social consequences. To improve outcomes for these individuals, it is imperative to have a detailed understanding of what exactly constitutes a ‘successful smile.’”