Which came first, the chicken or the film adaptation?

When a movie is made from a book, is it better to read the book first, or see the movie first?

Watching a movie (especially with a large crowd) is an intense, mob-mentality experience. When suspense or tension arise, shortly to be paid off one way or another, you're gripped the entire time. Surprises and reveals are better experienced with the excitement of a crowd, in the visual format of a movie, than they are in the pages of a book -- since you always watch a movie all at once, but rarely read a book all at once, watching a movie is a singular, more concentrated experience. Watching a movie, you're not going to suddenly find that it's time to go to bed, or to work, and be interrupted.

A movie, done right, leaves you wanting to know more about that world, to experience it in more depth. Afterward, when you read the book, you get to have that, by seeing what was left out of the (necessarily abbreviated) filmic version, what was changed, or even what was added. Certain kinds of books, like histories or biographies, rarely have a traditional dramatic structure, and so it is better for your first experience of the material to be in a powerful dramatic form, rather than as a (relatively) dry narrative of a person's life. Also, reading the book after seeing the movie allows you to spend more time contemplating the material in its entirety, since you're already somewhat familiar with it from having seen the movie version.

However... When a book is made into a movie, that's (widely considered) to be the cultural apotheosis of our age, the pinnacle of where entertainment media can go. "Oh my god! They're making a movie out of [insert novel/TV show/webcomic/joke on gum wrapper]!" (I look forward to the film adaptation of Verizon's "Can you hear me now?" commercials. Hopefully he gets hit by a truck.)

And this means that the novel (or whatever source material) is already a popular, well-known thing, and so you might already have read it, meaning you don't ever get the choice of whether to read the book or see the movie first. You could always choose to never read anything unless you've already seen the movie version, but I don't think most people would consider that a viable option. (Then there's the red-headed stepchild of the entertainment industry: Film novelizations. What's even worse is when a novelization is made of a film that was adapted from some other source.)

It occurs to me that maybe the ideal read/watch order depends on what kind of source material the book is. Biographies, histories, and stories in The Atlantic Monthly probably should be read after seeing the movie. If I'd read The Orchid Thief before seeing Adaptation., the experience probably would have been unavoidably tainted by my knowledge of the novel. The same goes for Seabiscuit; despite its flaws, the movie was more engaging when I had no idea what was going to happen, than it would have been had I read the book beforehand. (I did read it after; haven't gotten around to The Orchid Thief yet.)

What about fiction? Would I have wanted my first introduction to the world of Harry Potter to have been the 2001 film? Probably not; it was fine, as movies go, but I think lacked a lot of the magic that came from diving headlong into the literary version.

On the downside of book-first, there have been few surprises for me in any of the four Potter film adaptations, since I already know what's going to happen, and that's hardly entertaining. I certainly wouldn't have wanted to wait five years to read Harry Potter and the Goblet of Fire, trying the whole time to avoid finding out who dies in the end. That goes double for Harry Potter and the Half-Blood Prince, where a much more important character dies (or "dies," depending on which loony theories you believe). To be fair, it has been five years since I read Goblet of Fire, and so the movie did hold some surprises, where I had forgotten a plot twist or two. (Emma Watson needs to get those damn eyebrow muscles under control. I felt like she was in danger of causing structural damage to every ceiling she passed under.)

There's probably no good solution. At best, we can avoid reading a novel within a year of the movie coming out; that way, our memory of it will be faded at best, and the movie version will hold some surprises. If a movie is announced, and we haven't read the book, then maybe it's better to wait to read it until after seeing the movie. (Assuming we're interested.)