For eight months in 1998 and 1999, I woke every morning in search of chimpanzee pee. That pee held the key to the chimps’ testosterone levels, and I helped to catch it. To do this, I would hike through the rainforest to the trees in which the chimpanzees had built their sleeping nests the previous evening. The field assistants and I would wait under them, as bird and monkey calls gradually filled the air. Then came the rustling sounds from the nest above us—our cue to get ready. Chimps are not so different from humans in many respects, including this one—first thing they do when they wake up in the morning is urinate (they just had to stick their butts over the side of the nest). When they did, we would try to catch some of their pee, using a special tool crafted on our hike—a long stick with a plastic bag tied around the forked end. I would pipette some of that pee into a test tube and bring the samples back to the research site for storage. Later, they would be brought back to the lab at Harvard, so others could measure the chimpanzees’ testosterone levels.
Each chimpanzee knows his or her place in the status hierarchy. They signal that status to one another in various ways (vocalizations, body postures and movements, aggression, etc). Long-term data—some that we collected as part of the Kibale Chimpanzee Project in Uganda and some from other sites—clearly demonstrate that dominance rank among chimpanzees is related to testosterone levels. The dominant males tend to have the highest testosterone. They also let their presence be known by, among other tactics, making themselves look and sound as large as possible and taking up more physical space.
Inspired by this kind of work, in 2010, researchers at Harvard and Columbia proposed and tested a theory about how people could become more powerful. By placing their bodies into positions typically used by dominant males, people’s hormones could be, in essence, tricked into a dominant state, leading to more powerful behavior. Thus the concept of power posing was born.
Their small study seemed to support the theory. Then, in 2012, one of the study’s authors, Amy Cuddy, a psychologist at the Harvard Business School, gave a TED talk in which she described the paper’s results. Her talk is now the second most popular in the organization’s history (more than 36 million views). Her follow-up book, 2015’s Presence: Bringing Your Boldest Self to your Biggest Challenges, quickly became a best-seller. Power posing has been even said to work on horses.
It is also almost certainly ineffective. As you may already know, a larger-scale attempt to replicate the key findings, conducted by Eva Ranehill et al. in 2015, failed. The original study had serious methodological problems, including a very small number of subjects and data that were “p-hacked”—manipulated in creative ways until statistical significance was achieved. Then, at the end of September of this year, the lead author of that 2010 study, Dana Carney, did something almost unheard of in science: She posted a strong and detailed disavowal of the study on her website, writing that she no longer believed the effects of power posing were real. Once a media darling, power posing is now more often in the news as a cautionary tale about overhyping preliminary findings and p-hacking. Both of these issues contribute to findings that cannot be replicated, a massive issue plaguing social science and biomedical research right now.
But the rise and fall of power posing also highlights some deeper problems, which are exposed when we understand how hormones and power are related in humans—a relationship that isn’t nearly as simple as often assumed. This oversimplification matters, especially because power posing has been largely sold as a method women can use to gain social and professional success. More troublingly, power posing theory glorifies the behavior of the alpha male and encourages us to emulate it to improve our lives.
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When I watch Cuddy’s TED talk I feel myself rooting for her as she roots for all of us. She discloses her own personal fight to feel that she belongs, and she wants us to know that we can feel we belong too. Like her, I have felt like an impostor, especially in the male-dominated world that I inhabit (also at Harvard, where I received my Ph.D. in biological anthropology and where I teach a course called Hormones and Behavior). She is an inspirational speaker with a compelling personal story: In college she suffered a traumatic brain injury that put her ability to graduate in doubt. But through determination and hard work, she not only graduated but reached the academic summit, a Harvard professorship. You only need to take one look at the reviews of her book to be convinced that she has indeed helped many people to make positive changes in their lives.
In her TED talk, Cuddy notes that women tend to feel less powerful than men, and when they come into her classroom, they are more likely to “make themselves tiny” in comparison to men, who “like caricatures of alphas … really want to occupy space.” Unsurprisingly, power posing has a special appeal to women.
For the study, the researchers recruited 26 women and 16 men and had them spit into tubes before and after assuming either “low power” poses (taking up less physical space, say by scrunching up) or “high power” poses (taking up more space, a bit like manspreading). The participants next played a gambling game and indicated how powerful they felt. The saliva samples were sent to a lab for hormonal assays. The published results seemed to confirm that the poses affected participants’ hormone levels in the predicted ways: after high power posing, testosterone—which Cuddy calls the dominance hormone— increased, and cortisol—the stress hormone—decreased. The opposite pattern occurred after low power posing. Participants also took more risks in the gambling game, and reported feeling more powerful, after high posing. The researchers attributed these effects to the apparent hormonal changes.
The hormonal changes are what lent the findings real weight: In her talk, Cuddy explains that posing for “two minutes lead to these hormonal changes that configure your brain to basically be either assertive, confident, and comfortable or really stress-reactive and feeling sort of shut down.” This is more than “fake it till you make it”; this presumes that the very act of faking it gives you a biological leg up that will assist you in making it.
But for power posing to work as described, three assumptions must be true: First, adopting simple poses for two minutes reliably alters testosterone and cortisol levels; second, this works similarly in men and women; and third, relatively small changes in these hormones rapidly alter how we feel and behave.
Before we examine these assumptions, let’s talk about what we know about the two hormones at play. Cortisol has many diverse functions, but primarily it is a metabolic hormone, regulating blood sugar levels. It is produced by the adrenal glands and makes energy available when the body detects a need for it, such as when blood sugar is low or when we feel threatened, preparing us (along with other hormones such as adrenaline), mentally and physically, for fight or flight. Cortisol doesn’t cause the feeling of stress, and it doesn’t always increase when we experience stress. A relatively high level of cortisol may be a biomarker of psychological stress, but it can also mean you just woke up or finished a long run. In general, cortisol is highest when we wake up, because it releases energy when our stomachs are empty and then declines throughout the day.
While cortisol differs somewhat between the sexes, testosterone, the other hormone of interest, differs dramatically. Like estrogen, testosterone is critical in reproduction, coordinating reproductive physiology and behavior. Men have high levels of testosterone—seven to 10 times women’s levels—and among other functions, it helps to regulate processes and traits that support the competition for mates, including reproductive maturity, muscle mass, aggression, dominance striving, and sperm production. Both men and women produce testosterone, but they produce different amounts from different parts of their bodies: In men, the testicles produce the bulk of testosterone, while in women, the ovaries produce about a quarter of testosterone, with the rest coming from the adrenal glands and fat cells.
With that information in mind, let’s consider the assumptions made by the power posing theory one at a time. First: Can you change your hormone levels by briefly putting your body into simple poses?
It’s not likely. It is possible that if the participants felt relaxed, cortisol could have dropped. But it’s hard to believe that changes in testosterone were induced by two minutes spent holding different positions. This is not only supported by the literature on experimentally induced testosterone changes but also by my personal experience with such experimentation.
When I was a graduate student, I assumed that I could simply manipulate subjects’ testosterone levels—and then get to the real experiment of testing the effect of those changes on cognitive processing. I was inspired by studies showing that testosterone sometimes increases in men before competitions, where status seems to be at stake, and remains elevated after wins but decreases after losses, a phenomenon dubbed the winner-loser effect (this has been observed in physical and nonphysical competition, in sports fans and in players). I took advantage of our location in the Boston area to recruit some avid Red Sox fans (I even gave prospective subjects a quiz to make sure they were real fans). I had these nostalgic men listen to tapes of the original radio broadcasts of some of the most famous winning and losing moments in Red Sox history and measured the changes in their hormones. No effects whatsoever.
Undaunted, I tried another avenue—I had read a scientific article from the 1970s reporting that viewing pornography increased male testosterone, so I brought male Harvard undergraduates into the lab and showed them hardcore pornography. Again, no significant hormone changes. In a desperate attempt to make something of what I thought were failed experiments, I admit to doing what I now understand is p-hacking, or trying to find a way of analyzing the data that would show significant results. I struck out. I never submitted those studies for publication, assuming they weren’t worth publishing. Of course, if journals published more negative results I might have used more effective methods to try to alter participants’ testosterone levels. (And I might have been spared the experience of applying to get permission for the study, which involved watching porn with the director of Harvard’s internal review board.)
My experience as an instructor in human evolutionary biology has reinforced my earlier impressions of how difficult it is to induce natural changes in testosterone levels. I have worked with many students who have conducted research in our reproductive endocrinology lab, testing hypotheses about testosterone changes in males. One senior thesis in particular stands out as having been exceptionally well-designed: The student was then captain of the Ultimate Frisbee team, and he tracked players through a Frisbee tournament, measuring testosterone levels before, during, and after the wins and losses. Yet again, nothing. One student did discover the winner-loser effect in wrestlers, but that was before my time. In the 16 years since I’ve been at Harvard, to the best of my knowledge, no other students have found support for this kind of effect.
So, in my experience, watching porn, playing sports, winning at sports, and reliving some of the most memorable and moving moments in sports have not yielded significant changes in testosterone levels in men. It would be extremely surprising if simply standing tall for two minutes did.
As for the second assumption that women could increase their testosterone levels in the same way as men? Based on the differences in how the sexes produce and use testosterone, this is even more unlikely. But let’s consider the literature.
As Cuddy describes in her talk, part of the inspiration for the power posing study was the observation that male primates experience an increase in testosterone and a decrease in cortisol after they have gained in social status. A similar pattern has been found in other mammals—and it appears that such hormonal changes, whether temporary or longer lasting, serve to reinforce the behaviors that led to competitive success, e.g. not backing down from a threat. But these testosterone-behavior dynamics are rarely found in women or other female mammals. And there are good reasons why this should be true: The sites of testosterone production are vastly different, and testosterone-mediated responses that may be adaptive for males (e.g. territoriality, physical aggression, reduced attention to offspring) may be maladaptive for females (some exceptions here). From a physiological and evolutionary point of view, it would be quite surprising if any hormonal responses to power posing were the same in men and women.
But there’s also a problem in the way the data were reported. In her talk, Cuddy implies that the sexes experienced the same hormonal changes. In studies where researchers examine hormones such as testosterone and estrogen, data should always be analyzed and reported separately for each sex. But in the paper, the data weren’t broken down by sex, so we can’t tell whether the reported hormone changes really were similar for men and women. It’s perfectly possible that, if there were any significant hormonal changes, they only occurred in men.
Finally, the third assumption: Is it likely that changes in testosterone and cortisol could rapidly affect our feelings or behavior? We know that cortisol can act within minutes to help us respond to stressful situations and that relaxation can be accompanied by decreases in cortisol. But there is not much evidence that testosterone variations in humans shape feelings or behaviors so rapidly. For example, in studies where men are injected with a significant amount of testosterone, they report no difference in mood (see this and this paper). There is some evidence (e.g. here) that when women’s testosterone levels are artificially increased (to relatively high levels), fear, anger, and risk-taking are affected—but these changes occur on the scale of hours, not minutes. There is compelling evidence that testosterone does restructure the brain, and we still have lots to learn about this. But the most robust evidence indicates that it typically acts slowly and has long-lasting effects.
Taken in sum, the scientific evidence suggests that the central assumptions of power posing are unfounded. It is unlikely that power posing could change hormone levels so quickly, could alter hormones similarly in men and women, or could influence our emotions through changes in hormones. The failures to replicate the principal findings of the original study should come as no surprise given the science behind hormone-behavior relationships.
Responding to Carney’s disavowal in September, Cuddy defended her work by explaining that behavioral and hormonal changes are not the “key effects” of power posing. Instead, what matters, she now says, is that “adopting expansive postures causes people to feel more powerful.” She goes on: “While I am confident about the key power posing effect on feelings of power and the overall evidential value of the literature, I am agnostic about the effects of expansive posture on hormones.” Agnosticism (at the very least) is also the right attitude about the effects of expansive posture on behavior: A forthcoming analysis of 24 subsequent studies on power posing (mentioned by Carney) concludes that there is no empirical support for the hypothesis that it has behavioral or physiological effects.
Ranehill’s replication failed to find significant changes in behavior or hormones as a result of posing. It did find that those who power posed reported feeling more powerful—but the results show that the effect only occurred in men. There were no significant effects on reports of feelings of power in women. Cuddy says that the reports of powerful feelings after posing confirm her “key effect.” But this is a puzzling statement for several reasons, not least of which is that the power posing advice has been repeatedly marketed to women as a quick way to increase your edge in a male-dominated world. Furthermore, it’s also not at all surprising that people would report feeling more powerful after being told to stand in a masculine pose. The reason the original paper received so much attention is that it went beyond this. You weren’t just reporting that you felt powerful (self-reports are notoriously unreliable, which is why evidence of behavioral and/or physiological changes is so important); you actually felt and behaved more powerfully because hormones were affecting your brain. That was what all the excitement was about, also clearly reflected in the title of the original study—“Power Posing: Brief Nonverbal Displays Affect Neuroendocrine Levels and Risk Tolerance.” Without the hormonal and behavioral effects, power posing is reduced to an exercise that might simply lead you to say that you feel more powerful.
This is unfortunate because the motivation behind the power posing movement was admirable—it represented an effort to help people, particularly women, to feel more confident and powerful and thus to make positive changes in their lives. It’s too bad it didn’t work. But is there really any harm in encouraging people to stand powerfully for a couple minutes?
Actually, maybe. One problem is that the theory and its assumptions have led to an oversimplification of what testosterone does, likely arising from a misunderstanding of how and why testosterone increases in animals that achieve dominance. Animals don’t attain their high status and a testosterone boost by standing on a mound and spreading their arms and legs; they achieve dominance through a much more intricate and intertwined set of factors, including personality, experience, size, strength, and the social and physical environment. The bottom line is that testosterone-behavior relationships are highly complex.
But a deeper, more important point is that power posing theory, in suggesting that we mimic high testosterone poses, glorifies the alpha male. Let’s not.
While I was in Uganda studying chimps, I came to know the animals pretty well. All the chimps had very different personalities, some basically kind, some less so. The dominant male in the community was, to be quite frank, an asshole. I can’t think of much about him I’d want to emulate, even if he did hold all the power and a higher than average amount of testosterone. He achieved his high status partly through his ability to form loyal coalitions, but also because he was quick to anger and highly aggressive to those who did not properly display their subordinate status. And he was particularly brutal toward the adult females. Research from long-term studies on chimpanzees (here and here) shows that this kind of behavior, in essence, serves to remind the females who’s in charge. In fact, males are more likely to father offspring with the females toward whom they are most aggressive. This kind of aggression keeps females sexually available to high-testosterone, dominant males. And from an evolutionary point of view, the strategy pays.
This is all well and fine for chimps that lack the ability to consciously reflect on the morality of their behavior. But human beings have evolved big brains and the capacity to make deliberate choices about how we behave. Whether something is in our nature, or in the nature of our close primate relatives, has no bearing on whether it is good for humans. But in this case, the evidence is clear: The alpha-male, high-testosterone model of power and confidence isn’t one we should all seek to emulate. So perhaps we should be relieved that power posing doesn’t raise your testosterone and lower your cortisol—that particular hormonal profile has the downside of predicting aggression in human in addition to nonhuman males. There are other paths to confidence and power.
A few years ago, I got to know a young woman who had been a student in my Hormones and Behavior class. The next year, she came back to my class and gave a guest lecture to 65 of her fellow students. She revealed the following: She had failed to menstruate by her late teens, when a medical exam revealed that she possessed XY sex chromosomes (typical of males) and internal testicles that secreted high levels of testosterone. She had a condition called complete androgen insensitivity syndrome, in which her testosterone (more accurately, androgen) receptors were nonfunctional. With her usual poise, she explained that she chose to retain her testicles because the testosterone they produce is naturally converted into the estrogen that “feminizes” her. To put it mildly, she is not lacking in confidence, courage, and self-possession, yet she has no testosterone shaping her brain (or anything else) at all.
We should stop perpetuating the idea that testosterone is the way toward power and confidence.
We can stand plenty tall without it.
