Famous psychology study ‘killed by replication’: does a pencil in your mouth make you feel happy?

Replication is very important in science, but sometimes the results can hurt. Hurt a lot. Yesterday I found this new replication meta-study on a very famous insight in psychology via this tweet by Stuart Ritchie:

The study he discusses is the 1988 study by Strack, Martin & Strepper:

We investigated the hypothesis that people’s facial activity influences their affective responses. Two studies were designed to both eliminate methodological problems of earlier experiments and clarify theoretical ambiguities. This was achieved by having subjects hold a pen in their mouth in ways that either inhibited or facilitated the muscles typically associated with smiling without requiring subjects to pose in a smiling face. Study 1’s results demonstrated the effectiveness of the procedure. Subjects reported more intense humor responses when cartoons were presented under facilitating conditions than under inhibiting conditions that precluded labeling of the facial expression in emotion categories. Study 2 served to further validate the methodology and to answer additional theoretical questions. The results replicated Study 1’s findings and also showed that facial feedback operates on the affective but not on the cognitive component of the humor response. Finally, the results suggested that both inhibitory and facilitatory mechanisms may have contributed to the observed affective responses.

It’s a famous study and I think there is indeed a big chance you’ve heard about the results.

But this new replication meta-study examining 17 studies replicating the original research is quite damning:

According to the facial feedback hypothesis, people’s affective responses can be influenced by their own facial expression (e.g., smiling, pouting), even when their expression did not result from their emotional experiences. For example, Strack, Martin, and Stepper (1988) instructed participants to rate the funniness of cartoons using a pen that they held in their mouth. In line with the facial feedback hypothesis, when participants held the pen with their teeth (inducing a “smile”), they rated the cartoons as funnier than when they held the pen with their lips (inducing a “pout”). This seminal study of the facial feedback hypothesis has not been replicated directly. This registered replication report describes the results of 17 independent direct replications of Study 1 from Strack et al. (1988), all of which followed the same vetted protocol. A meta- analysis of these studies examined the difference in funniness ratings between the “smile” and “pout” conditions. The original Strack et al. (1988) study reported a rating difference of 0.82 units on a 10 point Likert scale. Our meta-analysis revealed a rating difference of 0.03 units with a 95% confidence interval ranging from -0.11 to 0.16.

Or shown as an image:

https://pbs.twimg.com/media/CqJkhbBVUAEDZgN.jpg

Via the tweet conversations following the tweet by Stuart Ritchie I also found this reply by Strack and this reply on this reply by the researchers.

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