No, seriously, who's laughing? You can probably scratch them off your "they might be a sociopath list".
From Sputnik:
A new study from British researchers has found that along with compulsive lying, narcissism and a failure to return video tapes on time, one telltale sign of a psychopath is that they do not share laughter with others.The team out of University College London studied 92 boys between the ages of 11 and 16. Thirty were a control group, while 62 had exhibited "disruptive behaviors" such as aggression, violence, lying, manipulation, enjoyment of Huey Lewis and The News, and a lack of guilt or a lack of concern. Many of these are the same signs as antisocial personality disorder (ASPD) according to the Mayo Clinic.
The boys who demonstrated the early warning signs for ASPD were less likely to laugh at both genuine and forced laughter. In addition, the MRI revealed that the "disruptive" boys showed less neural activity in response to the laughter and crying than the control group.After controlling for IQ, age, ethnicity, socioeconomic status and even what their dominant hand was, the boys were subjected to the experiment. Each was hooked up to an MRI and asked to listen to recordings of genuine laughter, forced laughter and forced crying. On a scale of one to seven, the boys were asked "How much does hearing the sound make you feel like joining in and/or feeling the emotion?" and "How much does the sound reflect a genuinely felt emotion?"
The purpose of this experiment was to show that laughter is a social cue, and most people will laugh or smile when another person around them does the same....MORE