While Kanwisher probes the brain’s handling of faces and places, Anthony Wagner uses fMRI to explore memory. Along the way, he may have solved a century-old mystery: Why do individuals learn better when they stretch out their studies instead of cramming?

People studying vocabulary cards, he notes, remember new words better if they knock off for successively longer stretches rather than pushing ahead with repetition after repetition.

Wagner, an assistant professor of brain and cognitive sciences, says a nineteenth century scientist “documented that spacing out your practices while trying to memorize specific information leads to better retention.” The faculty member thinks he has found the explanation.

The backdrop for his work is the fact that memory isn’t a unified ability, but exists in various forms. Short- and long-term memories are well-known examples, but differences exist even within these forms.

There are what most of us think of as memories: names and faces, major events, a favorite poem. Then there are essentially nonconscious memories. “You’re not aware of the memory representations you use when you ride a bike,” notes the scientist.

Even words can end up in one of the brain’s nonconscious memory banks. Volunteers asked to finish incomplete words — “th__g_t” (thought), “b_c__le” (bicycle) — do better on words they’ve recently viewed on a list even if they have no recollection of seeing those words.

Through his own word-learning experiments, Wagner found that such nonconscious memories can hurt our ability to lay down unique conscious memories. When there’s a gap between one showing of a word and the next, though, the dampening effect fades.

Wagner has a strong hunch why a longer lag time aids in solidifying memories. It’s essentially a notion employed in memory-boosting courses for years, which is that the more things you can connect with a specific memory — “Ah yes, that phone exchange is the same as Grandma’s street address” — the better you remember.

One key to learning, then, seems to be building up links between what you’re trying to learn and various “hooks” that help you access the items you’re committing to memory.

“The nonconscious memory arising from your earlier study of an item,” Wagner argues, “can reduce how much you elaborate mentally on that item, and this can impair your ability to remember it later on.”