This year’s Oscar nominees for best picture include four films based on true stories: “American Sniper” (about the sharpshooter Chris Kyle), “The Imitation Game” (about the British mathematician Alan Turing), “Selma” (about the passage of the Voting Rights Act in 1965) and “The Theory of Everything” (about the physicist Stephen Hawking).

Each film has been criticized for factual inaccuracy. Doesn’t “Selma” ignore Lyndon B. Johnson’s dedication to black voting rights? Doesn’t “The Imitation Game” misrepresent the nature of Turing’s work, just as “The Theory of Everything” does Mr. Hawking’s? Doesn’t “American Sniper” sanitize the military conflicts it purports to depict?

You might think: Does it really matter? Can’t we keep the film world separate from the real world?

Unfortunately, the answer is no. Studies show that if you watch a film — even one concerning historical events about which you are informed — your beliefs may be reshaped by “facts” that are not factual.

In one study, published in the journal Psychological Science in 2009, a team of researchers had college students read historical essays and then watch clips from historical movies containing information that was inaccurate and inconsistent with the essays. Despite being warned that the movies might contain factual distortions, the students produced about a third of the fake facts from the movies on a subsequent test. ...