“The surface of the psychopath… shows up as equal to or better than normal and gives no hint at all of a disorder within. Nothing about him suggests oddness, inadequacy, or moral frailty,” psychiatrist Hervey M. Cleckley wrote in his 1941 seminal work, The Mask of Sanity.

Psychopathy is a personality disorder characterized by impulsivity, manipulative behavior, and a lack of empathy, fear and remorse. However, new psychology research suggests that while psychopathic individuals don’t feel these emotions as strongly as others, they can do a better job of pretending to display them than the average person.

Angela Book of Brock University in Canada and a team of researchers conducted three experiments on prison inmates and students to examine the ability of psychopathic individuals to mimic normal human emotions. They discovered “that individuals with psychopathic traits may be able to express fraudulent emotions that appear genuine to the people around them.”

The study, “The Mask of Sanity Revisited: Psychopathic Traits and Affective Mimicry,” was published in the online journal Evolutionary Psychological Science.

The research was inspired by Cleckley’s work, as well as the Mimicry-Deception Theory.

Daniel N. Jones of the University of Texas at El Paso proposed theory in 2014 to explain predatory behaviors in human societies. A key aspect of the Mimicry-Deception Theory suggests that individuals involved in predatory behavior need to appear to be cooperative and “normal” to successfully take advantage of others. People are naturally wary of individuals who do not express fear or remorse, deeming them untrustworthy.

For psychopathic individuals to successfully navigate the social world, they “need to feign moral emotions in order to appear trustworthy and encourage others to cooperate with them,” Book and her colleagues explained in their study.

“By feigning remorse, individuals who lack these emotions may profit from appearing to by trustworthy while retaining the ability to pursue their own interests (without being hampered by any real emotions or concerns.)

The researchers found that individuals scoring higher on measures of psychopathy did a better job of reproducing facial displays of fear after being asked to mimic a fearful face.

Individuals scoring higher on measures of psychopathy were also better at pretending to be remorseful after being asked to tell a story about a true event that warranted remorse on their part, but for which they felt no guilt.

“Cleckley’s use of the title ‘The Mask of Sanity’ may be more appropriate than even he knew,” the researchers concluded.