Butler, whose research focuses on how cognitive psychology can be applied to enhance educational practice, notes that teachers can guard against the adverse impact of movies that play fast and loose with historical facts, although a general admonition may not be sufficient.

'The misleading effect occurred even when people were reminded of the potentially inaccurate nature of popular films right before viewing the film.

'However, the effect was completely negated when a specific warning about the particular inaccuracy was provided before the film,' Butler said.

'Although films may increase learning and interest in the classroom, educators should be aware that students might learn inaccurate information, too, even if the correct information has been presented in a text,' he concluded.

The study will be published in Psychological Science.