Michael Inzlicht and Sukhvinder Obhi in The New York Times:
The human brain can be exquisitely attuned to other people, thanks in part to its so-called mirror system. The mirror system is composed of a network of brain regions that become active both when you perform an action (say, squeezing a rubber ball in your hand) and when you observe someone else who performs the same action (squeezing a rubber ball in his hand). Our brains appear to be able to intimately resonate with others’ actions, and this process may allow us not only to understand what they are doing, but also, in some sense, to experience it ourselves — i.e., to empathize. In our study, we induced a set of participants to temporarily feel varying levels of power by asking them to write a brief essay about a moment in their lives. Some wrote about a time when they felt powerful and in charge, while others wrote about a time when they felt powerless and subordinate to others. The selection process was random, so that each participant had an equal chance of being powerful or powerless. Next, the participants watched a video of a human hand repeatedly squeezing a rubber ball. While they watched, we assessed the degree of motor excitation occurring in the brain — a measure that is widely used to infer activation of the mirror system. This motor excitation was determined by the application of transcranial magnetic stimulation and the measurement of electrical muscle activation in the subject’s hand. We sought to determine the degree to which the participants’ brains became active during the observation of rubber ball squeezing, relative to a period in which they observed no action.
We found that for those participants who were induced to experience feelings of power, their brains showed virtually no resonance with the actions of others; conversely, for those participants who were induced to experience feelings of powerlessness, their brains resonated quite a bit. In short, the brains of powerful people did not mirror the actions of other people. And when we analyzed the text of the participants’ essays, using established techniques for coding and measuring themes, we found that the more power that people expressed, the less their brains resonated. Power, it appears, changes how the brain itself responds to others.