Psychopaths less influenced by emotional "distractors"

New clues about psychopathy come from a study examining whether or not psychopaths, like other people, can be "distracted" from a task by emotion-laden stimuli.

Derek Mitchell and colleagues asked 35 prisoners, 16 of them classified as psychopaths, to perform a task in which they pressed a button with their left or right index finger depending on whether a circle or a square appeared on a screen. Before and after the shapes appeared, a positive, negative, or neutral image appeared briefly on the screen. The researchers told participants not to respond to the images, but to pay attention to them because questions might be asked about them later.

The researchers found that positive or negative images caused the non-psychopaths to slow their responses on the circle/square task to a greater degree than neutral images did. The psychopaths, however, performed just as well when emotional images bracketed the circle/square pictures as when neutral images appeared. The non-psychopaths also made greater errors when negative images bracketed the circle/square task, while the psychopaths did not.

The results are consistent with earlier research suggesting that psychopathy involves dysfunction of a brain region called the amygdala. Normally, the amygdala cues us to give preference to emotional over neutral stimuli in the environment when we are busy focusing on a task-something that did not occur in the psychopaths in this experiment.

However, the findings of Mitchell and colleagues differ from several other studies indicating that psychopaths have a specific impairment in responding to fear. In this study, psychopathic subjects showed an abnormal reaction to both negative and positive images.