https://pmc.ncbi.nlm.nih.gov/articles/PMC7193529/
Reconsidering the Duchenne Smile: Indicator of Positive Emotion or Artifact of Smile Intensity? -...
The Duchenne smile hypothesis is that smiles that include eye constriction (AU6) are the product of genuine positive emotion, whereas smiles that do not are...
duchenne smilepositive emotionreconsideringindicator