Experts have recognised for some time that not all psychopaths are violent criminals. Many of them live inconspicuously amongst us (see item 4 here). But according to Mehmet Mahmut and his colleagues, these more benign psychopaths have been relatively uninvestigated. It's not even clear how comparable they are to their more notorious counterparts.

Psychopaths showed less activity in brain areas involved in assessing the emotion of facial expressions, the British Journal of Psychiatry reports.In particular, they were far less responsive to fearful faces than healthy volunteers.

As a society, we’re both captivated and repelled by psychopaths and their seemingly endless potential to commit murder and mayhem. There’s no end to the number of movies made about them, not to mention true-crime novels and news stories that focus on such notorious psychopaths as Ted Bundy and Paul Bernardo. However, the popular portrayal of psychopaths is a little misleading. Since many of them do commit horrendous crimes, it’s easy to chalk them up as evil monsters. But there’s more to them than that. In fact, there’s a lot of new scientific research looking into the nature of psychopaths that suggests there’s a biological basis for their so-called evil behaviour.