Increasing perceived happiness in neutral faces by posing a smile: An electroencephalography (EEG) frequency-tagging study.

Previous research using electroencephalography has so far failed to provide strong and convincing evidence for the effects of facial feedback on the visual processing of emotional facial expressions. To fill this gap, we harnessed the power of electroencephalography frequency tagging, which offers excellent objective indication of implicit stimulus processing with high signal-to-noise ratio. Healthy adult participants (N = 47) from diverse backgrounds (tested in 2023/2024) viewed rare happy and angry oddball faces, interspersed with frequent neutral faces, while either producing a smile or keeping a neutral face. Smiling resulted in reduced neural discrimination of happy versus neutral faces over the left occipitotemporal region, as shown by decreased power at the oddball frequency. These findings could reflect that voluntary smiling, and the associated change in facial feedback, leads to neutral faces being perceived as happier, providing evidence for the facial feedback hypothesis. (PsycInfo Database Record (c) 2025 APA, all rights reserved).