In 2010, researchers at Harvard Business School claimed to have found (PDF) that striking powerful poses caused hormonal and behavioral changes. "Power poses" seemed to raise testosterone, lower cortisol, and increase risk-taking behavior.

As with all research, replication was needed to check the validity of the results. An attempt at replication using additional controls, published recently in Psychological Science, found no behavioral or hormonal effects of “power poses," although they did result in a boost in subjective perception of power. In other words, the original research did not hold up.

The idea that powerful poses could have hormonal effects ties in with a prominent idea in behavioral science: the hypothesis that physical interaction with the environment affects cognitive behavior. It would make sense that there should be a physiological vehicle (such as hormonal changes) for this effect.

A team of researchers led by Eva Ranehill at the University of Zurich tried to replicate the original Harvard Business School study with some important tweaks. First, they used a bigger sample size. The original study used 42 participants; the replication used 200. Secondly, they controlled for experimenter’s bias, which is the possibility that subtle cues from the researchers could be affecting the results.

The basic methods of the study were the same. Each participant started out by providing a saliva sample. They then performed a “filler” task while in a series of two different poses, either powerful or powerless. The powerful poses took up space, like leaning back in a chair with feet up on a table or leaning across a desk. In contrast, the powerless poses were closed in, like having someone hold their hands in their lap while hunched forward. The poses were the same as in the original study but were held for three minutes instead of the original one minute.

The replication deviated from the original study at this stage by giving the pose instructions via computer, which should prevent the researchers from subtly biasing their subjects. The experimenters' own biases were also handled because they didn’t witness this stage, so they wouldn’t know later on which poses the participants had taken. But, after the experiment was concluded, they reviewed footage of this step to ensure that participants had complied with the instructions.

Next, the participants played games that assessed their willingness to take risks—gambling a sure payment on the chance of a higher payment—and their inclination to be competitive in a math task. They provided a second saliva sample, allowing the researchers to compare their hormone levels before and after the power stances. Finally, they filled in a questionnaire that asked about their feelings of power and checked whether they had found their stances physically uncomfortable.

The results were very different from the original experiment. Participants who had taken powerful poses reported feeling more powerful, but there was no trace of this feeling in the behavioral tasks. Of course, it’s possible that these were just the wrong kinds of tasks and that a subjective feeling of power could influence behavior in circumstances other than risk-taking or competitiveness. Nonetheless, it represented a failure to replicate the result seen in the original study.

There was also no difference in hormone levels between the powerful group and the powerless group. The researchers also analyzed the effect on each gender and checked whether it made any difference to exclude participants who had found the positions physically uncomfortable. There were still no significant differences in hormone levels.

What’s tricky here is that although this was a close replication of the original study, there were differences that could have been important. For one thing, the replication study didn’t use deception with participants. Participants were told before they started that the experiment was about hormones and body position (although they didn’t get any more detail). This could have had a subtle effect on the participants’ responses.

There was also the fact that the “filler” task used during the poses involved faces in the original study but words in the replication. It’s possible that the extra social element to the original task is what produced the effect. Finally, it’s worth considering that the populations were from different countries, raising the possibility of a cultural effect.

The conclusion is that replication is hard. In some ways, you need multiple replications of the replication to get a firm grip on problems like these. Each study will help to eliminate possibilities and raise more exact questions that can help to chase down a reliable, replicable effect.

Psychological Science, 2015. DOI: 10.1177/0956797614553946 (About DOIs).