By Matthew Warren

If you hear an unfounded statement often enough, you might just start believing that it’s true. This phenomenon, known as the “illusory truth effect”, is exploited by politicians and advertisers — and if you think you are immune to it, you’re probably wrong. In fact, earlier this year we reported on a study that found people are prone to the effect regardless of their particular cognitive profile.

But that doesn’t mean there’s nothing we can do to protect ourselves against the illusion. A study in Cognition has found that using our own knowledge to fact-check a false claim can prevent us from believing it is true when it is later repeated. But we might need a bit of a nudge to get there.