Andrew Gelman and Kaiser Fung write:
Consider the case of Amy Cuddy. The Harvard Business School social psychologist is famous for a TED talk, which is among the most popular of all time, and now a book promoting the idea that “a person can, by assuming two simple one-minute poses, embody power and instantly become more powerful.” The so-called “power pose” is characterized by “open, expansive postures”—Slate’s Katy Waldman described it as akin to “a cobra rearing and spreading its hood to the sun, or Wonder Woman with her legs apart and her hands on her hips.” In a published paper from 2010, Cuddy and her collaborators Dana Carney and Andy Yap report that such posing can change your life and your hormone levels. They report that the “results of this study confirmed our prediction that posing in high-power nonverbal displays (as opposed to low-power nonverbal displays) would cause neuroendocrine and behavioral changes for both male and female participants: High-power posers experienced elevations in testosterone, decreases in cortisol, and increased feelings of power and tolerance for risk; low-power posers exhibited the opposite pattern.”
Cuddy’s work on power posing has been covered in the press for years, including in Waldman’s tongue-in-cheek article in Slate. Most of the time, that coverage is glowing. Here’s a recent New York Times review of Cuddy’s new book, Presence: Bringing Your Boldest Self to Your Biggest Challenges: “While Cuddy’s research seems to back up her claims about the effects of power posing, even more convincing are the personal stories sent to the author by some of the 28 million people who have viewed her TED talk. … Unlike so many similar books aimed at ushering us to our best lives, Presence feels at once concrete and inspiring, simple but ambitious—above all, truly powerful.” And here’s a CBS News report from last month: “Believe it or not, her studies show that if you stand like a superhero privately before going into a stressful situation, there will actually be hormonal changes in your body chemistry that cause you to be more confident and in-command. … [M]ake no mistake, Cuddy’s work is grounded in science.”
But the story of power posing is not so simple. An outside team led by Eva Ranehill attempted to replicate the original Carney, Cuddy, and Yap study using a sample population five times larger than the original group. In a paper published in 2015, the Ranehill team reported that they found no effect.
This is not such a surprise. Cuddy’s scientific claim was, as is typically the case, based on finding “statistically significant” results in experiments. We know, though, that it is easy for researchers to find statistically significant comparisons even in a single, small, noisy study. Through the mechanism called p-hacking or the garden of forking paths, any specific reported claim typically represents only one of many analyses that could have been performed on a dataset. A replication is cleaner: When an outside team is focusing on a particular comparison known ahead of time, there is less wiggle room, and results can be more clearly interpreted at face value. The original power-pose study reported an impressively large effect, but that’s what happens with published results from small, noisy studies: Variation is high, so anything that does appear to be statistically significant (the usual requirement for publication) will necessarily be large, even if it represents nothing but chance fluctuation.
