Researchers analysed the hands of 80 individuals. (Representational Pic)
Many actors have played the role of a psychopaths in films throughout the years, like The Joker and American Psycho. Some of them have received accolades for essaying the characteristics commonly associated with psychopaths, such as superficial charm, lack of empathy, and a penchant for manipulation. Scientists have said that psychopaths display a grandiose sense of self-worth and a propensity for boredom, leading to risk-taking behaviour. But it is very difficult for common people to identify psychopaths around them, without a thorough research.
But now, a study has revealed an easy way to identify a psychopath in the real world - from their hands.
Researchers from the Centre de Recherche Charles-Le Moyne in Quebec have claimed that people who have a longer ring finger than index finger are more likely to have psychopathic tendencies.
The researchers also said the findings suggest that psychopathy may be "biologically rooted".
"While individuals with such behaviours are socially highly problematic and incur issues, such behaviour might be biologically rooted and understood as a fast life history strategy," the researchers wrote in the study published in the Journal of Psychiatric Research.
For the study, researchers analysed the hands of 80 individuals. While 44 participants had a clinical diagnosis of amphetamine use disorder (AUD), antisocial personality disorder (ASPD) or both, 36 were healthy.
The researchers took detailed scans of their right hands and put them through several psychological evaluations, including one designed to test for Dark Triad personality types - narcissism, Machiavellianism and Psychopathy.
Higher scores on these tests indicated that the subject had higher levels of psychopathic and antisocial traits.
Researchers said the results revealed a clear link between a lower 2D (index finger) and 4D (ring finger) ratio and antisocial traits, as well as higher scores on the Dark Triad personality tests.
Serge Brand, lead researcher on the paper, spoke to PsyPost about the research and explained the results are strongly associated with an increased exposure to testosterone and with a decreased exposure to estrogen in the womb.
"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," he said.
The researcher, however, stressed that a low 2D:4D ratio is not an absolute indicator of psychopathy.
"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," said Mr Brand.