A new study by Nicholas Christenfeld and Jonathan Leavitt of the UC San Diego psychology department suggests that a spoiled story might actually be more enjoyable than experiencing a story as it was intended to be consumed. The study was performed using spoilers with books (subjects who already read the stories were excluded) but they speculate about film and several real life implications that may also apply.
What's even more powerful about the findings is that the 12 novels came evenly from three different story structures -- literary, mystery, ironic twist -- and all but one of the novels was more enjoyed with spoilers. I wonder if it's less about the desire for something easy (we like our tools to be easy, so why not our stories/art too?) and more about meeting expectations. Foretelling events beforehand makes it seem less like a journey and more like a self-fulfilling plot that's guaranteed to meet the goal that's stated up front, so the ending feels like a success instead of an author's choice.
For example, the Romeo and Juliet prologue ruins the entire story, so perhaps "show don't tell" is better than simple narration, but not as good as "tell, then show" as the superior storytelling structure? Maybe Shakespeare was ahead of his time in more ways than we currently know! Enough speculation though; check out the entire study preview -- a study spoiler, if you will -- here, and look forward to the complete study getting published in an upcoming issue of the Psychological Science journal.