From The Guardian:
A study by Nicholas Christenfeld and Jonathan Leavitt of UC San Diego's psychology department, due to be published in the journal Psychological Science, gave subjects 12 short stories, by authors including Agatha Christie, Roald Dahl and John Updike. Some were presented in their classic form, others with spoiler paragraphs, with each version read by at least 30 people. And you know what? The spoiled readers actually had more fun.
http://www.guardian.co.uk/books/booksblog/2011/aug/17/spoilers-enhance-enjoyment-psychologists
Interesting:
I wonder if this might imply that one should telegraph the ending when writing a story.
It goes against what I've been taught, but who knows?