Smiling for a split second makes people more likely to see happiness in expressionless faces, new research from the University of Essex has revealed.
The study led by Dr Sebastian Korb, from the Department of Psychology, shows that even a short weak smile makes faces look happier.
The groundbreaking experiment used electrical stimulation to induce smiles and was inspired by photographs made famous by Charles Darwin.
A painless current manipulated the muscles momentarily into action – creating a brief uncontrollable smile.
This is the first time that electrical stimulation of the face has been shown to affect emotional perception.
Dr. Korb hopes the research can explore potential treatments for depression or disorders that affect expression, such as Parkinson’s disease and autism.
He said: “The finding that a controlled, brief and weak activation of facial muscles can literally create the illusion of happiness in an otherwise neutral or even slightly sad face is groundbreaking.
“It is relevant for theoretical discussions about the role of facial feedback in emotion perception and has potential for future clinical applications.”
Dr Korb used a modernized version of a technique first developed in the 19th century by the French doctor Duchenne de Boulogne.
Darwin published drawings of Duchenne’s work in The Expression of the Emotions in Man and Animals – his third major work on evolution.
However, the trend was reduced for the new experiments to ensure the safety of the participants and to better control the smiles.
Using computers, the team was able to control the appearance of the smile with millisecond precision.
A total of 47 people took part in the Essex study published in Social Cognitive and Affective Neuroscience.
They were shown digital avatars and asked to rate whether they looked happy or sad. In half of the trials, the smiling muscles were activated at the beginning of the face.
It turned out that producing a weak smile for 500 milliseconds was enough to induce the perception of happiness.
Dr. Korb says the results help us understand facial feedback and hopes to expand the study.
We are currently conducting more research to further investigate the phenomenon in healthy participants.
In the future, however, we hope to apply this technique to explore facial emotion recognition, for people with conditions such as Parkinson’s disease, who are known to have impaired spontaneous facial mimicry and impaired facial emotion recognition.
In addition, we have published guidelines to allow other researchers to safely begin using electrical stimulation of facial muscles.”
Dr Sebastian Korb, Department of Psychology, University of Essex
Source:
Journal Reference:
Efthymiou, Th. et al. (2024) Zygomaticus activation by facial neuromuscular electrical stimulation (fNMES) elicits the perception of happiness in ambiguous facial expressions and affects the neural correlates of face processing. Social Cognitive and Emotional Neuroscience. doi.org/10.1093/scan/nsae013.
