One might say smiling is unique to humans. And though smiling is most often a manifestation of our humanity and our sincerity, some smiles are decidedly “fake.” Why? Probably because, as American and European scientific teams have demonstrated, we can now make miniature replicates of a person’s smile. Invisibly tiny muscle contractions in our face attest to the authenticity of our smile.
During a discussion, we are often compelled to smile or to acknowledge the smile of our interlocutor. Our smiles may reveal sincerity, betray boredom, or in the worst case, may even convey ridicule. A smile can thus relate a wide range of different expressions. Researchers at the University of Wisconsin and the University of Geneva conducted some elegant experiments: they “miniaturized” the smiles of various individuals and studied the invisible microcontractions of the muscles involved.
A smile expresses a real, inartificial positive emotion. It elicits a sort of unspoken understanding in the person receiving the smile. We activate the same muscular patterns as the person facing us. To understand what the other person feels, we either internally perceive these microcontractions or our brains process the motor commands sent to the muscles, giving us conscious access to this information. The theory is largely based on the discovery of mirror neurons (1990): neurons that fire in the same way after seeing someone carry out an action and when we carry out that same action ourselves.
The researchers shed light on the mechanism in an experiment involving 31 participants. Subjects watched 2-second video clips showing avatars with smiles that require the use of different facial muscles (corrugator, zygomatic, orbicularis oculi, and masseter). While the participants viewed the faces, the scientists observed the contraction of each of their facial muscles. Participants also judged the authenticity of smiles while viewing the videos.
What did they find? A “mimetic” pattern that imitated that of the video avatars. Furthermore, when the microcontractions were intense, the smile was deemed more authentic, involving most of the facial muscles. Is it possible to feign a genuine smile? Potentially, but only if it activates all of the facial muscles. Other factors must also be taken into account: posture, blushing or paleness of the skin. Faking that smile isn’t so easy after all!