Many children can ‘catch the giggles’ long before they can talk, laughing along with a parent as if by instinct.
But if a child doesn’t ‘laugh along’, it could be a worrying sign.
A UCL Study found that children who are at risk of developing psychopathy don’t find laughter as ‘contagious’ as it is for other people.
The researchers recruited 62 boys aged 11 to 16 with disruptive behaviour and other traits linked to a risk of psychopathy.
Playing the boys the sound of laughter while they sat in an MRI machine, the volunteers found that they didn’t respond as much to the sound of people laughing – with differences seen in areas of the brain associated with sociability.
MOST POPULAR STORIES ON YAHOO UK
Theresa May’s keynote Conservative Party conference speech interrupted by P45 stunt
Stourbridge murder: Homeless Aaron Barley jailed for life for stabbing mother and son
Donald Trump said he turned his back on ‘dying’ man aged 80 because it was ‘disgusting’
Boris Johnson slammed by top Tories over ‘dead bodies’ Libya comment
Final MH370 report calls plane’s disappearance an ‘almost inconceivable’ mystery
The boys also told researchers they didn’t feel like joining in with laughter.
Professor Essi Viding of UCL said, ‘We wanted to investigate how boys at risk of developing psychopathy process emotions that promote social affiliation, such as laughter.
‘Those social cues that automatically give us pleasure or alert us to someone’s distress do not register in the same way for these children.
‘That does not mean that these children are destined to become antisocial or dangerous; rather, these findings shed new light on why they often make different choices from their peers. We are only now beginning to develop an understanding of how the processes underlying prosocial behaviour might differ in these children.’