Imagine that on Day 1 of a difficult course, before you studied a single thing, you got hold of the final exam. No answer key, no notes or guidelines. Just the questions.

Would that help you study more effectively? Of course it would. You would read the questions carefully. You would know exactly what to focus on in your notes. You would search the textbook for its discussion of each question. On the day of that final, you would be the first to finish, sauntering out with an A+ in your pocket.

But what if, instead, you took a test on Day 1 that was just as comprehensive as the final but not a replica? You would bomb the thing, for sure. You might not understand a single question. And yet as disorienting as that experience might feel, it would alter how you subsequently tuned into the course itself — and could sharply improve your overall performance.

This is the idea behind pretesting, one of the most exciting developments in learning-science. Across a variety of experiments, psychologists have found that, in some circumstances, wrong answers on a pretest aren’t merely useless guesses. Rather, the attempts themselves change how we think about and store the information contained in the questions. On some kinds of tests, particularly

multiple-choice, we benefit from answering incorrectly by, in effect, priming our brain for what’s coming later.

The basic insight is as powerful as it is surprising: Testing might be the key to studying, rather than the other way around. As it turns out, a test is not only a measurement tool. It’s a way of enriching and altering memory.