Isn't it interesting when someone posts a highly positive comment on Facebook and tons of their friends "like" the post and chime in with like-minded comments? Likewise, the same happens with negative comments. This is no coincidence. A new study published in Plos One on Wednesday by researchers from the University of California at San Diego says that moods on Facebook are contagious. While negative posts definitely beget negative posts, positive posts are apparently more infectious. "Our study suggests that people are not just choosing other people like themselves to associate with but actually causing their friends' emotional expressions to change," James Fowler, UC San Diego School of Medicine professor and the study's lead author, said in a statement. "We have enough power in this data set to show that emotional expressions spread online and also that positive expressions spread more than negative." Read the full story at CNET.