A multi-lab test of the facial feedback hypothesis by the Many Smiles Collaboration.

Following theories of emotional embodiment, the facial feedback hypothesis suggests that individuals' subjective experiences of emotion are influenced by their facial expressions. However, evidence for this hypothesis has been mixed. We thus formed a global adversarial collaboration and carried out a preregistered, multicentre study designed to specify and test the conditions that should most reliably produce facial feedback effects. Data from n = 3,878 participants spanning 19 countries indicated that a facial mimicry and voluntary facial action task could both amplify and initiate feelings of happiness. However, evidence of facial feedback effects was less conclusive when facial feedback was manipulated unobtrusively via a pen-in-mouth task.

Your Face and Moves Seem Happier When I Smile.

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.

The effect of occlusal contacts on adjacent tooth.

PURPOSE: The purpose of this study was to clarify the influence of changes of occlusal contacts on adjacent tooth displacement during articulation. MATERIALS AND METHODS: The amount and direction of displacement of the maxillary left first molar and adjacent teeth were measured using a displacement transducer, Type M-3. Seven subjects were included in this study. On the maxillary left first molar, 8 experimental occlusal contact points were established using platinum foil and these were divided into 2 groups, the buccal and lingual groups, which corresponded to the buccal and lingual cusps, respectively. RESULTS: During clenching, the buccal group showed differences in the direction of the tooth displacement paths among the 3 teeth (second premolar, first and second molar), but there was no difference in the lingual group and the direction of displacement of these 3 teeth was similar to the natural teeth. CONCLUSION: It is necessary to make at least one lingual occlusal contact point to obtain displacement of not only the abutment tooth but also the adjacent teeth.