Mean world syndrome is a proposed cognitive bias wherein people may perceive the world to be more dangerous than it is. This is due to long-term moderate to heavy exposure to violence-related content in mass media. In the early stages of research, mean world syndrome was only discussed as an effect of watching television. However, it became clear that social media platforms also play a major role in the spread of mean world syndrome.

George Gerbner was a professor of communication and the founder of cultivation theory. He taught at Temple University, Villanova University, and the University of Pennsylvania.