Psychopaths are more likely to show this surprising physical trait: study

Are you a stone-cold psychopath? The answer could be right in your hands.

Researchers in Canada have analyzed the finger lengths of volunteers with clinically diagnosed psychiatric issues to determine whether psychopathy is “biologically rooted.”

The team found that those whose index fingers are shorter than their ring fingers are more likely to have a diagnosed psychiatric disorder. The results of the study have now been published in the February edition of The Journal of Psychiatric Research.

The team started out by noting that those who have a lower 2D:4D-ratio — ie: a shorter index finger and a longer ring finger — are already known to be more commonly associated with “Dark Triad” traits and aggressive behavior.

“Dark Triad” traits are “highly socially discouraged attitudes, namely Machiavellianism, narcissism and psychopathy.”

The paper noted that people who score high on the “Dark Triad” scale have “also scored high on mental toughness and sports performance, but also on various types of negative psychosocial and psychological outcomes, including intolerance of uncertainty, anxiety sensitivity callous affect, and interpersonal manipulation.”

For the scientific study, the researchers recruited 80 volunteers: 44 with psychiatric issues and 36 healthy individuals without any diagnosed mental conditions.

An analysis of their hands confirmed that “compared to healthy controls, individuals with a clinically diagnosed psychiatric issue were more likely to have a shorter index finger and longer ring finger.”

The investigation uncovered that, compared to the healthy controls, individuals with a clinically diagnosed psychiatric issue were more likely to have a shorter index finger and longer ring finger.

The results also confirmed that lower “2D:4D-ratios were associated with higher ‘Dark Triad’ traits.”

But the study’s lead author, Serge Brand, is warning people with shorter index fingers not to fret, saying it’s very common.

 A lower 2D:4D-ratio is also associated with a prenatally higher testosterone and lower estrogen exposure during the first trimester the fetal stage, according to Brand.

“The more an adult participant had signs of psychopathology, the more it appeared that this adult has been exposed to higher testosterone concentrations and lower estrogen concentrations during the prenatal period of life,” Brand told PsyPost.

However, he added: “It is important to understand that the finger lengths-ratio as a proxy of a specific exposure to prenatal sex steroids should not be understood as a person’s irrevocable fate.”