Study Links Psychopathic Personality Traits With Activity In A Specific Part Of The Brain


Dr. Alfredo Carpineti

Senior Staff Writer & Space Correspondent

clockNov 26 2018, 17:56 UTC

The prefrontal cortex is the region of the brain associated with planning, decision making, and learning. SpeedKingz/Shutterstock

Philosophy has been battling with moral dilemmas for thousands of years. People choosing right or wrong, good or evil, matters a lot in a social species like ours. There are many factors at play in this conundrum, but researchers may have begun to understand what goes on in the brain when a moral judgement is being made.

In two new studies, researchers have used functional near-infrared spectroscopy (fNIRS) to analyze how brain activity correlated to certain moral judgments.


In the first study, the team looked at the brain activity of 33 individuals who were asked two variations, one personal and one impersonal, of the famous thought experiment known as the trolley problem, while being monitored by the fNIRS. They wanted to know if the differently framed problem activated different parts of the brain.

The personal dilemma was as follows: There’s a trolley on a track hurtling towards five people. You can either push a man off a footbridge where his body would intercept the trolley or do nothing and let five people die. Most people choose not to push the person in front of the trolley which is considered the nonutilitarian option.

The impersonal approach is the classic version of the problem: The trolley is on track to kill five people, but it is possible to divert it onto another track with just one person, killing them with a flick of a switch. Studies have shown that most people kill one person. This is the utilitarian option.


In the paper, published in Brain and Behaviour, the team found that indeed different parts of the brain were activated depending on the personal or impersonal dilemma. Most noticeably, the nonutilitarian option in the impersonal dilemma (doing nothing and letting five people die) elicited a particular response in the left lateral region of the prefrontal cortex (the part of the brain involved in decision making and learning).

In the second study, published in Behavioural Brain Research, the team looked at the relationship between brain activity during moral judgment making and "psychopathic" personality traits. Given that most people can exhibit certain psychopathic traits, they wanted to try and establish a baseline in a healthy population.

"Having these baselines allows us to compare these measurements to individuals whose behaviors have been classified as ‘psychopaths’ and potentially provide intervention outcome measures or future therapeutic targets,” senior author Dr Amir Gandjbakhche told PsyPost


They found in the personal dilemmas that classic psychopathic traits such as coldheartedness and carefree non-planfulness were associated with activity in the left lateral regions of the prefrontal cortex. In the impersonal ones, instead, it was the right lateral prefrontal cortex that activated during dilemmas testing Machiavellian egocentricity, rebellious nonconformity, coldheartedness, and carefree non-planfulness.

However, a lot more work is needed to fully understand the importance of these correlations in understanding and maybe even treating psychopathic tendencies. 

“Our study presents data and results that shed light on how functional neural activity and behavior may be tied. We expect that fNIRS can eventually be used to assess disorders that manifest in behaviors that reflect psychopathic traits, such as antisocial personality disorder, conduct disorder, etc,” Gandjbakhche said.


“This project will potentially assist in the creation of a tool that allows for early detection of psychopathic traits, which may lead to improved diagnoses, treatments, and preferable outcomes for patients and society.”

[H/T: PsyPost]