You can tell a lot about how someone is feeling by how they swing their arms

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Looking at how someone swings their arms when walking could help gauge their mood, according to international researchers. They found people had a better than chance ability to judge someone's emotions from a motion capture video. The team says coordinated swinging of arms and legs is connected to emotion, and that by manipulating the frequency of swinging arms, they could change the observer's assessment of the walker's emotions. Larger arm movements were perceived to be linked with anger, and reduced movements with sadness, they say.