Can you tell when a person is lying to you? The secret might be their smile, according to researchers at the University of Rochester. After looking at the expressions people have when telling the truth or lying, the researchers found that liars were most often given away by the sheer delight that showed on their faces.
1.3 Million Expressions to Analyze
For this study, researchers recruited volunteers using Amazon Mechanical Turk. The volunteers were then split into 151 pairs, one who would be the “interrogator” and the other who would be the “describer.” The interrogator asked questions, and describers had to respond. First, all the interrogators asked a few baseline questions that the describers had to answer truthfully. This helped researchers create a pool of expressions related to truthfulness.
Then interrogators asked questions about a picture that the describers had seen. Some describers were told to be truthful. Others were told to lie.
In total, this sample size gave researchers a grand total of 1.3 million frames of expressions to analyze. Then they tried to correlate certain expressive features that were linked to lying.
The Joy of Lying
When describers responded to questions, researchers found, they had five different characteristic types of smiles. The one that was most closely linked to lying was the Duchenne smile.
The Duchenne smile is named after the mid-19th century French Neurologist Guillaume Duchenne, who conducted experiments on facial muscles and discovered the smile. This type of smile involves the orbis oculi muscle, which raises the cheeks and crinkles the corner of the eye. Duchenne linked the smile with a more genuine happiness and said it was a true smile of joy. That’s because, he said, the orbis oculi muscle is involuntary. People can’t control it, so if they’re using it, it’s only because they’re happy.
However, in the 150 years or so since Duchenne’s theories, there has been some evidence that some, if not most people, can actually control the orbis oculi muscle to make their smile look genuine. Despite this, the statement from University of Rochester says that it’s not possible to fake the display that gives liars away.
A Truly Beautiful Smile
The University of Rochester research reminds us that there are many reasons why people choose to smile. And no matter your reason to smile or not, having an attractive smile makes it more comfortable to show your smile.