Psychopaths are commonly seen as people who do not consider the thoughts and feelings of others. Or when they do, they don't care about those thoughts and feelings. Arielle Baskin-Sommers of Yale University has been studying psychopaths for ten years. She works with inmates in a maximum-security prison, where 106 volunteers were divided into psychopaths, non-psychopaths, and those with some psychopathic tendencies. What she found was that psychopaths can and do put themselves in another person's place, but that is a deliberate decision for them, while normal people learn to see other people's perspectives automatically as we mature.
Most of us mentalize automatically. From infancy, other minds involuntarily seep into our own. The same thing, apparently, happens less strongly in psychopaths. By studying the Connecticut inmates, Baskin-Sommers and her colleagues, Lindsey Drayton and Laurie Santos, showed that these people can deliberately take another person’s perspective, but on average, they don’t automatically do so to the extent that most other people do. “This is the first time we’re seeing evidence that psychopaths don’t have this automatic ability that most of us have,” Baskin-Sommers says.
The researchers found this out by doing innocuous experiments that pinpoint how difficult a subject finds separating their own viewpoint from another person's viewpoint. Those experiments are explained at The Atlantic.