Have you ever not known how to feel? Ever think a joke is not humorous until someone else laughs? Ever been with a group of people who are angry or upset and suddenly you become angry and upset for no reason? This are social contagions, which, according to changingminds.org, is emotion spreading rapidly through crowds. Common examples of social contagions include laughing, yawning, menstruation,making purchases, language, emotions, and even obesity.
In our books, Psychology: From Inquiry to Understanding mass hysteria and urban legends are focused on. According to the book, mass hysteria is a "contagious outbreak of irrational behavior that spreads much like a flu epidemic" and urban legends are false stories repeated so many times that people believe them to be true. Mass hysteria is also capable of leading to collective delusions, most commonly as UFO sightings. In reality, 98% of all UFO sightings can be accounted for by misinterpretations of familiar phenomena. However, once UFO is mentioned, people will go out looking for them and will then typically label normal sightings, such as airplanes and shooting stars, as UFOs.
Urban legends are very popular among all age groups because, although as ridiculous as some may be, they are definitely plausible. Most urban legends provoke disgust, curiosity, and fear, which all grab anyone's attention who has fallen victim to the possibility of these stories. The most recent urban legend I have fallen victim to is that of Slender Man, a tall, faceless man in a black suit with extendable arms that kidnaps you when you think of him. I lost a weeks worth of sleep over this all thanks to my oh-so-wonderful roommate! Urgh! For more information on Slender Man, I suggest watching the MarbleHornets documentary-style string of videos on YouTube to get a truly chilling sense of him.
There is very little hard evidence as to why there are social contagions. All we can really tell from them is that as human beings we are largely effected by the thoughts, feelings, and actions of others. We are highly susceptible to extreme emotions such as happiness, anger, and uneasiness and when others experience these emotions we are extremely likely to mirror their thoughts and feelings. Imagine all of the times you've been having fun with friends. Everything is going great and everyone is happy, that is, until that one person brings everyone down by bringing a bit of drama into the picture and ruins everyone else's moods and evenings. Social contagions are everywhere and effect us greatly in our everyday lives, even when we are completely unaware of them!