Studying feels productive because it's the easy version
Two psychologists ran the same experiment twice and found that the study habit almost everyone trusts is quietly the weaker one.
In 2006, Henry Roediger and Jeffrey Karpicke gave college students a short passage to learn. Some students reread it twice. Others read it once, then had to recall it from memory with no notes and no feedback — effectively a pop quiz on themselves.
Tested five minutes later, the re-readers won comfortably. Tested a week later, the pattern reversed hard: the group that had quizzed themselves once remembered dramatically more than the group that had reread the material four times over.
This is the finding that anchors Make It Stick, by Peter Brown, Henry Roediger, and Mark McDaniel: retrieval — the effortful, uncomfortable act of trying to pull an answer out of your own memory — builds durable learning in a way that smooth, fluent rereading doesn't. Rereading feels like progress because it's easy. That ease is exactly the problem.
The students who reread also felt more confident about the coming test. They were also the ones who did worse on it.