It's disappointing that so many comments are deriding the results of this study. I think this study is actually underestimating the effect of social contagion

It's disappointing that so many comments are deriding the results of this study. I think this study is actually underestimating the effect of social contagion through social media, not just for emotional states but political views as well. While I think this type of social contagion happens through all forms of media, social media is highly individualist so I think the effect is slightly different. I don't think it's a coincidence that the explosion of identity politics over the past ten years lines up with rise of social media. This individualism is especially obvious with post-modernist leftists - just think of how many Twitter bios start off with listing someone's gender identity, mental illnesses, ethnicity, etc. Leftist social media is more of a subculture than an actual political movement, with no discussion or debate before ideas are treated as wrongthink.