Want to feel better? Make a fake smile by holding a pencil in your teeth.

Neat work by Marmolejo-Ramos et al in Experimental Psychology, Research subjects who forced their facial muscles to replicate the movement of a smile by holding a pen between their teeth altered their perception to see the world in a more positive way, and to have a lower threshold for the perception of happy expression in facial stimuli. This correlated with changes in activity of the amygdala, an emotion regulation center in the brain. I pass on their abstract (motivated readers can obtain the whole article by emailing me):

In this experiment, we replicated the effect of muscle engagement on perception such that the recognition of another’s facial expressions was biased by the observer’s facial muscular activity (Blaesi & Wilson, 2010). We extended this replication to show that such a modulatory effect is also observed for the recognition of dynamic bodily expressions. Via a multilab and within-subjects approach, we investigated the emotion recognition of point-light biological walkers, along with that of morphed face stimuli, while subjects were or were not holding a pen in their teeth. Under the “pen-in-the-teeth” condition, participants tended to lower their threshold of perception of happy expressions in facial stimuli compared to the “no-pen” condition, thus replicating the experiment by Blaesi and Wilson (2010). A similar effect was found for the biological motion stimuli such that participants lowered their threshold to perceive happy walkers in the pen-in-the-teeth condition compared to the no-pen condition. This pattern of results was also found in a second experiment in which the no-pen condition was replaced by a situation in which participants held a pen in their lips (“pen-in-lips” condition). These results suggested that facial muscular activity alters the recognition of not only facial expressions but also bodily expressions.