Belief perseverance (also known as conceptual conservatism) is maintaining a belief despite new information that firmly contradicts it. Such beliefs may even be strengthened when others attempt to present evidence debunking them, a phenomenon known as the backfire effect (compare boomerang effect). For example, in a 2014 article in The Atlantic, journalist Cari Romm describes a study involving vaccination hesitancy. In the study, the subjects were concerned of the side effects of flu shots, and became less willing to receive them after being told that the vaccination was entirely safe.