Hypothesis
Following the view that facial expressions are universal reflections of inner states, smiling in daily selfie videos would be inversely related to self-reported psychological distress.
What failed
In 24 undergraduates who recorded a two-minute video each evening for 14 days and completed the DASS, PSS and PSQI at the end of each week, smiling intensity correlated positively with individual differences in anxiety, depression and stress, the opposite of the prediction.
Broken assumption
A smile recorded on camera indexes how the person actually feels.
Why
The authors read the counterintuitive direction as a challenge to the assumption that facial expression necessarily reflects inner emotion, and present the result as preliminary given the small sample.
From the published paper: Lind et al. Journal of Trial and Error, 2024. ↗CC BY