Can you vaccinate your mind against misinformation?

Partly yes: showing people a weakened dose of manipulation, with the trick explained, can make them better at spotting it later, but the protection fades. This is inoculation theory, developed by the psychologist William McGuire in 1961, an analogy to how a body gains resistance to disease. Medical inoculation exposes the body to a weakened form of a virus, strong enough to trigger a response but not so strong as to overwhelm it. Attitudinal inoculation exposes you to weakened counterarguments, which trigger your defences against stronger attacks later.

McGuire was motivated by the aftermath of the Korean War. Nine US prisoners of war, when given the opportunity, chose to remain with their captors, and many people assumed they had been brainwashed. Until then, persuasion research had almost exclusively asked how to make messages more persuasive. McGuire asked the opposite question: how do you make people resistant?

The idea has a modern form called prebunking. Once people have seen misinformation, its influence is much harder to remove, which is why debunking and fact checking have often failed. Prebunking gives people a harmless example in advance. In 2022 researchers tested five short prebunking videos on 29,116 people, who then did better at telling manipulative posts from benign ones, by about 5 percent on average. A free browser game, Bad News, lets players play a fake news tycoon to learn the tricks.

The catch: that benefit decays after several weeks, so researchers suggest repeated booster shots. The vaccine comparison is useful, but this vaccine needs topping up.