From Bruce Bower:
Facebook users can spread emotions to their online connections just by posting a written message, or status update, that’s positive or negative.This finding challenges the idea that emotions get passed from one person to another via vocal cues, such as rising or falling tone, or by a listener unconsciously imitating a talker’s body language.It’s time to rethink how emotional contagion works, since vocal cues and mimicry aren’t needed.