When we learn, we usually begin with the basics and work our way up, mastering our do-re-mi’s before launching into an aria. But when people have difficulty speaking and understanding language after a stroke—a condition called aphasia—they seem to improve faster when they start at a harder level.

Speech researcher Swathi Kiran of Boston University works with bilingual aphasia patients to help them relearn words. She has found that when pa­tients practice the language they speak less fluently, their vocabulary grows in both languages. But when the patients study words in the language they are more comfortable in, only that language improves.

Although Kiran has not yet pub­lished a study on her bilingual patients, her observation is in line with her ear­lier, published papers and those of other researchers. These studies show that aphasics who speak only one language also benefit from more diffi­cult practice. When aphasics study unusual words in a category—such as “parsnip” and “rutabaga” when relearning vegetable names—they also improve their fluency with common words in that category (“pea” and “carrot”). Likewise, practicing complex sentences helps aphasics handle simple ones.

This technique works because of the way that a healthy brain stores language, Kiran says. As we learn new information, the brain stores the words, languages and grammatical structures that we use most often in a way that makes them easy to access. Harder words are more like items at the bottom of a box—we must rifle through the items we use more often to reach the buried rarity. To retrieve an unusual word such as “rutabaga,” then, we activate the easily accessible parts of our vegetable-naming network on our way to getting to the word itself, which strengthens our connections to common words such as “carrot,” too.