Spacing effect

In everyday life

A student who reviews vocabulary for 15 minutes a day over a week remembers more on test day than a classmate who spends the same total time studying the night before.

You learned a friend's new phone number by glancing at it once a day for a week and still know it months later, while a code you drilled 20 times in one sitting is long gone.

Why your mind does this

Memory is rebuilt each time we recall it, which lets us update what we know with new information. Revisiting a memory also strengthens it, so the things we return to often become the easiest to reach. This keeps our knowledge current without storing every version of every event.

Its family, in 30 seconds: Edited memories

How to spot it

Notice when you plan to learn something important in one long cram session.

What you can do

Use this effect to your advantage: review in short sessions spread over days, with growing gaps between them.