Boys who don’t feel the urge to laugh when others around them do might be at risk of developing psychopathy when they become adults, a new study has found.
Published in Current Biology, the research shows that boys who exhibited disruptive traits alongside a lack of emotion were also less respondent to the sound of laughter.
To collect their data, scientists analysed the behaviour of 92 boys between the ages of 11 and 16.
"Most studies have focused on how individuals with psychopathic traits process negative emotions and how their lack of response to them might explain their ability to aggress against other people," explains lead author Essi Viding, who teaches at University College London.
"This prior work is important, but it has not fully addressed why these individuals fail to bond with others. We wanted to investigate how boys at risk of developing psychopathy process emotions that promote social affiliation, such as laughter."
Whilst 30 of the participants were deemed to exhibit normal behaviour, the remaining 62 were labelled disruptive and callous, which the scientists recognised as common traits amongst individuals at risk of developing psychopathy.
"It is not appropriate to label children psychopaths," Viding added. "Psychopathy is an adult personality disorder. However, we do know from longitudinal research that there are certain children who are at a higher risk for developing psychopathy, and we screened for those features that indicate that risk."
The boys were all tested on their cognitive response to laughter, which was monitored using MRI.
Participants listened to a range of laughter clips, including moments of genuine laughter, forced laughter and crying sounds, reports Science Daily.
Researchers subsequently asked them how much the sounds made them feel like joining in and how genuine they sounded. The boys answered on a scale of one to seven.
They found that those from the disruptive and callous group were more likely to abstain from laughter when others were laughing around them.
However, Viding admits that it’s tricky to know whether the subdued response to laughter is a direct result of the boys’ disruptive traits and explained that her findings provoke further research into how psychopathy comes to be in children.
In future studies, her team intend to uncover whether the disruptive children respond distinctly to smiling faces, displays of affection and encouraging phrases.
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