Desirable Difficulty

Some obstacles make learning stronger — and are therefore desirable. This sounds like a schoolmaster's excuse until you see the evidence.

Compare two students. One rereads the chapter five times; it flows, it feels productive. The other closes the book and struggles to recall it, writes it messily, gets parts wrong. Days later, the second student remembers. The first remembers the feeling of having studied.

The principle: memory strengthens in proportion to the effort of retrieval, not the comfort of review. Easy in means easy out. A thing that cost you effort to pull out of your mind stays in your mind.

So design difficulty into your practice on purpose. Study in scattered sessions rather than one long one. Test yourself instead of rereading. Change locations, vary problems, let yourself forget a little before returning. If the practice feels pleasantly smooth, suspect it. The strain is the signal.