Power Posing: P- Curving the Evidence

In a well-known article, Carney, Cuddy, and Yap (2010) documented the benefits of “power posing”. In their study, participants (N=42) who were randomly assigned to briefly adopt expansive, powerful postures sought more risk, had higher testosterone levels, and had lower cortisol levels than those assigned to adopt contractive, powerless postures. In their response to a failed replication by Ranehill et al. (2015), Carney, Cuddy, and Yap (2015) reviewed 33 successful studies investigating the effects of expansive vs. contractive posing, focusing on differences between these studies and the failed replication, to identify possible moderators that future studies could explore. But before spending valuable resources on that, it is useful to establish whether the literature that Carney et al. (2015) cited actually suggests that power posing is effective. In this paper we rely on p-curve analysis to answer the following question: Does the literature reviewed by Carney et al. (2015) suggest the existence of an effect once we account for selective reporting? We conclude not. The distribution of p-values from those 33 studies is indistinguishable from what is expected if (1) the average effect size were zero, and (2) selective reporting (of studies and/or analyses) were solely responsible for the significant effects that are published. Although more highly powered future research may find replicable evidence for the purported benefits of power posing (or unexpected detriments), the existing evidence is too weak to justify a search for moderators or to advocate for people to engage in power posing to better their lives.