How you perceive emotions in others can have a real impact on how you feel yourself, according to a new study.


The new research, published in the journal Psychological Science, shows that training people to be biased to recognize happiness instead of anger in a facial expression can help to lower their own feelings of aggression and anger.


"Our results provide strong evidence that emotion processing plays a causal role in anger and the maintenance of aggressive behavior," study researcher Marcus Munafo, a professor at the university, said in a statement. "This could potentially lead to novel behavioral treatments in the future."


Researchers from the University of Bristol conducted their study on both healthy volunteers, and teens who are known to either have a high risk of committing a crime or having aggressive behavior. In the first part of the study, the researchers had 40 healthy volunteers rate a series of facial expressions as happy or angry, so that they could see a "baseline" of how the volunteers would read the expressions. Then, the researchers told the volunteers that some of the faces they considered "angry" were in fact happy.


By "training" these volunteers in this way, they started to find happiness in the "angry" faces, and they reported feeling less aggressive or angry themselves.


The researchers found a similar result when they conducted the same experiment with the teens (ages 11 to 16). Plus, the teens had fewer aggressive incidents in the weeks following the experiment.


"These studies provide strong evidence that emotion processing plays a causal role in anger and the maintenance of aggressive behavior," the researchers wrote in the study.


Last year, a study in the same journal showed that a happy facial expression -- specifically, a genuine smile -- can help to decrease stress by lowering heart rate after a tense event.


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