Cimorene

That's true. But I don't think they meant to imply that it should work that way when applied in real life; maybe they did.

It makes sense that a gifted child, for whom a puzzle was easy, would choose a more difficult one when praised that "you must have worked hard" (even if they were confused because they hadn't). But what's unexpected about that result, to me, is - assuming that a bell-curve of intelligence was present in both groups (which isn't necessarily true, but could be) - that when praised on results, children of above-average intelligence chose the easy puzzle; and that when praised on effort, children who might have been truly challenged by the first puzzle chose one that they knew would be hard. It's interesting, both in what it says about adding motivation for average children, and how to kill motivation DEAD in the gifted.