“The fundamental concept in social science is Power, in the same sense that Energy is the fundamental concept in physics . . . The laws of social dynamics are laws which can only be stated in terms of power.”  -- Bertrand Russell

Three-quarters of a century ago, Bertrand Russell asserted that power is the driving force behind much of social behavior. Consistent with Russell’s theoretical musings, there has been an explosion of empirical research in the past decade – in social psychology, sociology, economics, and political science – demonstrating that power governs the many important social relationships that make up our political, business and family lives. Indeed, the dynamics of power even regulates the interactions of pre-school children. Power appears to be the central animating force of social life.

Given power’s primacy in social life, it is not surprising that one’s position in a social hierarchy transforms people in fundamental ways. Simply placing a person in a powerful or powerless role immediately alters their thoughts and behavior. The powerful tend to see the forest whereas the powerless focus on the trees. The powerful are optimistic, take bold actions and embrace risky ideas while the powerless are psychologically conservative. As Lara Tiedens of Stanford University points out, this complementarity of behavior leads to an efficient division of labor and smooth social relationships. Because it provides survival advantages to groups, hierarchy is the most prominent form of social organization. As a result, the human mind has evolved to be incredibly sensitive to one's own place in a social hierarchy.

Given the wide range of behaviors and cognition that power pulls into its sphere of influence, a fundamental question is how do people acquire power: what are its sources and bases? Many people answer “money, fame, or an important role in one’s social group.” Indeed, each of these may give you asymmetric control over valued resources, which is the very definition of power. But, are there other sources of power, other ways to both feel powerful and signal power to others?

In fact, there are many paths to increase one’s sense of power. The most obvious method is to have actual control over valued resources. But, power is also housed in our memories – simply recalling a time in which one had power has the exact same psychological and behavioral effects as giving people actual resource control. As memories of past power dance in our heads, we feel more powerful and act as if we are in charge in the present. However, although reliving powerful experiences can make one feel powerful, it doesn’t signal power to others.

As it turns out, there is a simple method to both transform people psychologically and signal power to others: altering your body posture. Across species, body posture is often the primary representation of power. From fish to reptiles to lower mammals to human’s closest evolutionary cousins, non-human primates, power is expressed and inferred through expansive postures, large body size, or even the mere perception of large body size through expansive postures.

The link from expansive postures to feeling and acting in a powerful way was elegantly demonstrated in a recent publication in Psychological Science. Dana Carney and Andy Yap from Columbia University and Amy Cuddy from Harvard University found that open, expansive postures (widespread limbs and enlargement of occupied space by spreading out one’s body), compared with closed, constricted postures (limbs touching the torso and minimization of occupied space by collapsing the body inward), increased feelings of power and an appetite for risk. To measure the appetite for risk, these researchers gave participants $2 and told them they could keep this money or roll a die and risk losing the $2 for a payout of $4 (a risky but rational bet since the odds of winning were 50/50). Participants who had been placed in the expansive posture reported feeling significantly more “powerful” and “in charge” and were also 45% more likely to roll the die.

More impressively, expansive postures also altered the participants’ hormone levels. Using salivary samples, Carney and colleagues found that expansive postures led individuals to experience elevated testosterone (T) and decreased cortisol (C). This neuroendocrine profile of High T and Low C has been consistently linked to such outcomes as disease resistance and leadership abilities. Although past research has found that occupying a powerful role leads to expansive postures, Carney et al.’s paper is the first to investigate the reciprocal relationship – the causal effect of posture on the mental experience of power.

Along with Deborah Gruenfeld and Lucia Guillory from Stanford University, we have further established the primacy of posture. In our studies, also appearing in Psychological Science, we empirically demonstrated that not only does expansive posture predict power-related behavior, but it might actually be the closest correlate of these behaviors. Across three studies, we found that when individuals were placed in high- or low-power roles while adopting an expansive or constricted posture, only posture affected the implicit activation of power, the taking of action, and the tendency to see the forest instead of the trees.

Together, these recent discoveries bolster the notion that power is grounded in the body. Not only does power change the body, but altering one’s postures changes one’s power, or at least the psychological experience of it.

These recent findings further suggest that if you want to predict how people will act in any given moment, it may make sense to look to their posture instead of their role or title. The battle between powerful roles and powerful postures is humorlessly depicted in a cartoon on the cover of the December 5, 2005 issue of The New Yorker. President George W. Bush is slouching. The then vice president, Richard B. Cheney, has both arms expansively extended across the back of a sofa, his legs sprawled across a coffee table. The president has more power vested in him by the Constitution, but the cartoon suggests what scientific research has found: that a person’s posture is often more indicative of actual influence than their position in a hierarchy.