It's questions the study should've been asking if it wanted truly significant results.
12 selected stories with no examination of their specific content? Sorry.
I think the cleverness of a twist might only be determinant when that's all the story has going for it, like the punchline of a joke.
Well what do you base this sweeping statement on again?
How about the story has to offer a lot, but the twist adds even more to the enjoyment?
LOST had to offer a lot, and I'd like some study on that showing that people who already knew the flashsides were a con and a duck, enjoyed it just as much.
What if the story is so engaging, it allows you to suck in the twist with loving passion without scrutinizing its crude underpinnings? The quality of the twist would matter in a lesser story, but less so here.
Then, of course, the are two components of the enjoyment, aren't there - before the twist, and after (or during). The surprise during the twist is what usually sticks in the memory the most.
So you'd have to ask the participants how they were feeling before the surprise, and how impressed they were with the WTF moment in the aftermath.