An amusing commercial shows someone having a bad day, and how that person’s mood affects each person down the line, with more bad moods. This emotional “contagion” may be a real-world phenomenon, and it appears that what we experience online can have a similar effect. Examining over 2000 video blogs, or vlogs on YouTube, researchers from Tilburg University, Netherlands, found we mirror the emotions of those we see online and we seek out people who share our emotions.