Science Daily: “Smiling for just a split second makes people more likely to see happiness in expressionless faces, new University of Essex research has revealed. The study led by Dr Sebastian Korb, from the Department of Psychology, shows that even a brief weak grin makes faces appear more joyful. The pioneering experiment used electrical stimulation to spark smiles and was inspired by photographs made famous by Charles Darwin. A painless current manipulated muscles momentarily into action — creating a short uncontrollable smile. This is the first time facial electrical stimulation has been shown to affect emotional perception. Dr Korb hopes the research can explore potential treatments for depression or disorders that affect expression, like Parkinson’s 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 looking face, is ground-breaking.”

Source: Themis Nikolas Efthimiou, Joshua Baker, Alasdair Clarke, Arthur Elsenaar, Marc Mehu, Sebastian Korb. Zygomaticus activation through facial neuromuscular electrical stimulation (fNMES) induces happiness perception in ambiguous facial expressions and affects neural correlates of face processing [full text free to read]. Social Cognitive and Affective Neuroscience, 2024; 19 (1) DOI: 10.1093/scan/nsae013