Boys at risk of developing psychopathy don’t have the same urge to join in group laughter than most people do, finds a study in Current Biology. Researchers tested 62 11- to 16-year-old boys diagnosed with disruptive behaviors, along with 30 age-matched controls. Half of the disruptive boys also showed high levels of callous-unemotional traits; the other half did not. After listening to recorded laughter, the 32 boys with both disruptive behavior and high level of callous-unemotional traits reported less desire to join in with the laughter, on average, than did the other boys. Also, fMRI scans showed that the boys with both disruptive behavior and callous-unemotional traits who listened to laughter had less brain activity in the anterior insula and supplementary motor area–brain regions believed to be involved in liking physical action (laughter) with emotional experiences. (Monitor on Psychology)

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