Facial feedback
Claim assessed: Your facial expression influences your emotions.
Published · how we work
In short
The facial feedback hypothesis says that your facial expression doesn’t just show what you feel but also influences what you feel. If you smile, you feel a little better; if you frown, a little worse. The idea was supported by a famous study with a pen held in the mouth, which a large replication didn’t find again. An even larger test showed, though, that a smile made on request has a small but real effect.
What it says
The pen study. Strack, Martin and Stepper (1988) asked participants to rate how funny some cartoons were while holding a pen in their mouth. Some held it between their teeth, which forces a kind of smile; others between their lips, which prevents one. The idea was that participants wouldn’t realise they were being made to smile. Those with the pen between their teeth found the cartoons funnier, by 0.82 points on a 0-to-9 scale. We haven’t read the study; we describe it from the replication below.
The replication in 17 labs. Wagenmakers et al. (2016) repeated exactly that study in 17 labs, with 1,894 participants, following a protocol vetted in advance. Strack provided the original materials and feedback early on, but declined to review the final protocol. The analysis and the text of the article were written before seeing the data. The difference was 0.03 points, practically zero, and none of the 17 labs found a difference at least as large as the original.
The joint test, Many Smiles. Coles et al. (2022) brought together researchers who believed in the effect, sceptics and some without a firm view. Together they decided in advance how the hypothesis should be tested and ran the study in 19 countries with 3,878 participants. People were asked either to mimic pictures of smiling people, to move certain facial muscles, or to hold the pen in their mouth. When they smiled by mimicking or by moving the muscles at will, they felt a little happier than with a neutral expression. With the pen, the effect wasn’t clear. The effect also appeared in participants who hadn’t guessed the study’s purpose, although it was larger in those who had.
Example
Before a hard day, someone decides to smile into the mirror for a few seconds. They may feel a little better in the moment. There is no evidence, though, that this changes well-being in the long run. The example is an illustration, not a study cited here.
How to apply it
The steps below are a practical way to apply it that we propose, based on the studies cited.
- Don’t expect much. The measured effect is small, about as large as that of mildly pleasant pictures.
- Don’t use smiling as a treatment. Many of the Many Smiles authors consider it unlikely that smiling will become a serious intervention for well-being or depression.
- Don’t believe in hidden tricks. The pen version, in which people don’t know they are smiling, didn’t work in replications.
- Use the case as a lesson in method. A famous study can vanish in a large replication, while the underlying idea survives, smaller, in a more carefully tested form.
Limits and nuances
- The effect is small. In Many Smiles, the difference was around half a point on a scale with a 6-point range, under 10% of the scale.
- Expectations matter partly. The effect was larger in participants who realised what the study was after, although it didn’t disappear in those who didn’t.
- Many Smiles ran online and measured happiness, not amusement. It differs from the original study in several ways, so it isn’t a direct replication of it.
- Some researchers explained the failed replication by participants being filmed. Many Smiles didn’t film them and still found no clear effect with the pen method.
- What we read. Wagenmakers et al. (2016), from the University of Amsterdam repository, and Coles et al. (2022), in the version accepted by the journal, from the Newcastle University repository, we read in full. We haven’t read Strack et al. (1988); we describe it from the replication.
Sources
- Fritz Strack, Leonard L. Martin, Sabine Stepper (1988). Inhibiting and facilitating conditions of the human smile: A nonobtrusive test of the facial feedback hypothesis
- Eric-Jan Wagenmakers, Titia Beek, Laura Dijkhoff, Quentin F. Gronau et al. (2016). Registered replication report: Strack, Martin, & Stepper (1988)
- Nicholas A. Coles, David S. March, Fernando Marmolejo-Ramos et al. (Many Smiles Collaboration) (2022). A multi-lab test of the facial feedback hypothesis by the Many Smiles Collaboration
See also: Cognitive reappraisal, Power posing