Spoiler alert: Story spoilers can hurt entertainment

"Our study is the first to show that people's widespread beliefs about spoilers being harmful are actually well-founded and not a myth," says Johnson. Furthermore, in a follow-up study, Johnson and Rosenbaum found that the effects of spoilers are actually linked to people's personality traits. Johnson: "While the worry and anger expressed by many media users about 'spoilers' in online discussions or reviews is not completely unfounded, fans should examine themselves before they get worked up about an unexpected spoiler."

The first study, published in Communication Research this month, tested how 412 university students responded to spoiled and unspoiled short stories. Spoiled stories were rated as less suspenseful and fun. Spoilers also reduced how 'moving and thought-provoking' a story was and how much the reader felt immersed into the story's world. Johnson says that the results were a bit of a surprise. "We expected spoilers to improve some outcomes, but hurt others. Instead, we saw consistently negative consequences of story spoilers," he says.

Quick, instinctive thinkers prefer spoiled stories

These findings contradict a study carried out by two researchers in California in 2011 that found spoilers could improve story enjoyment. Johnson and Rosenbaum attribute the competing results to differences in how enjoyment is understood and measured. They have also identified personality traits that lead people to seek out or dislike spoilers (in a publication due next year in Psychology of Popular Media Culture).

In that latest experiment, people's needs for cognition (enjoying deep thinking) and affect (enjoying emotional experiences) made a difference. "We found that people who have a low need for cognition prefer their stories to be spoiled, because it makes the plot easier to follow. Meanwhile, people who have a high need for affect enjoy unspoiled stories more, because they desire the thrill of a surprise," says Rosenbaum.