The Scientific American has published more research showing how you stand can affect your mood, your brain chemistry and the perceptions of others.
This reinforces my own experience doing work with postures, gestures and poses during acting classes. You discover quickly that if you assume a crouching, fearful pose, you can quickly work into an interior state that reflects fear and submission. Conversely, assuming open and royal postures -- head up, chin and chest out makes you feel powerful. Because you can exaggerate these in class more than in real life, the effect is more noticeable.
It's more reinforcement of how internal and external techniques can help an actor embody a character, an emotion, a human being. Just as Mr. Stanislavski and Mr. Michael Chekhov said.
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.
(This also reminds me of Keith Johnstone's book Impro -- one of the most casually profound books I've ever read -- in which he devotes a section to dominance on stage.)