Before a movie is released, it will often be shown to a test audience — or several test audiences — so producers can gain insight into how the public will react to the story, the characters, and the comedy. A preview screening does two things: Reveal what is working, and expose what isn’t. Believe it or not, a negative test screening has the power to alter the final form of a film — as is the case in all 12 of the pictures below.

12 Movies That Changed After Their Test Screenings

Whether it’s a complaint about a long runtime or a desire for a more satisfying ending, these audiences made their opinions heard. Here are 12 successful films whose test screenings shaped them into what they are today.