Using body language that communicates power makes people feel and act more in command, according to research led by Dana R. Carney, assistant professor of management at Columbia University. For two minutes, one group made "low power" gestures: crossing their arms and legs or holding their arms to their sides. Another group made expansive "high power" motions: standing with their arms braced wide on a table or sitting with their feet on a desk and their hands clasped behind their heads. In the dominant-posture group, testosterone production increased and the stress hormone cortisol dropped, while the opposite occurred in the group with weaker stances. Those who posed powerfully were also more likely to say they felt in charge and to take an opportunity to double their money in a gambling task. Evolutionarily, such gestures prepare animals and humans to face a challenge, the study authors note.