Scientists actually bothered to find out.

Since this study was based on reading rather than viewing fiction, there's no way to know if one medium is transferrable to another. Also, are those stories of unusually high quality? I only recognize "An Occurrence at Owl Creek Bridge," which is a classic. It could be that, for a small percentage of truly well written fiction, spoilers don't count as much because the quality of the storytelling doesn't diminish on re-reading. But I don't see much outta Hollywood that could have been written by Ambrose Bierce.
So to summarize, I'll quote a great comment at that link:

Well, MY hypothesis is that it's all down to the individual. Some people love spoilers, and for others, it really does ruin things.It turns out that spoilers don't actually ruin your enjoyment of entertainment.

Not for me. I very rarely re-read books or re-watch movies and TV shows. For the vast majority of stuff, the surprise element the first time around is vital, because most stuff isn't good enough to merit revisiting.The press release noted, "The overall findings are consistent with the experience most of us have had: A favorite tale can be re-read multiple times with undiminished pleasure. A beloved movie can be watched again and again."
Since this study was based on reading rather than viewing fiction, there's no way to know if one medium is transferrable to another. Also, are those stories of unusually high quality? I only recognize "An Occurrence at Owl Creek Bridge," which is a classic. It could be that, for a small percentage of truly well written fiction, spoilers don't count as much because the quality of the storytelling doesn't diminish on re-reading. But I don't see much outta Hollywood that could have been written by Ambrose Bierce.
So to summarize, I'll quote a great comment at that link:
So a group of scientists did a study on a frog. They taught the frog to jump every time someone said jump. So after teaching the frog to jump when someone said jump they cut off one of his legs. With only 3 legs they said jump and the frog jumped. So they cut off another leg and said jump. With only 2 legs he still jumped. They continued this until they had cut off all 4 of the frogs legs. Now when they said jump the frog didn't jump. So the results they learned are if you cut off a frogs legs he goes deaf. That is about as useful a study as this one.
