In 1988, psychologists at the University of Würzburg, Germany observed that people who held a pen between their teeth, which induces a smile, rated cartoons as funnier than did those who held a pen between their lips, which induces a pout. Recognizing these observations, the ‘facial feedback hypothesis’ — the idea that facial expressions can influence a person’s own emotional state has been demonstrated.

Recently, a group of scientists at the University of Amsterdam revised this experiment with different but equally funny cartoons and published their results collected from 17 experiments and nearly 1,900 participants. Overall, the experiments found no difference in rating the cartoons in people with pen-induced smiles or frowns; the experiments were powered enough to reach statistical significance but researchers found the same null result.

The study is one of several multi-lab efforts to replicate psychology findings, after the field was shocked by several accusations of fraud and faulty statistical analyses. Last year, many psychologists reported attempts to replicate the findings of 98 papers, and noticed that only few works could be replicated with similar results. Even if this experience was not a direct replication for many reasons, the original facial feedback hypothesis has been challenged.