The researcher Viorica Marian, of Northwestern University’s School of Communication, conducted a study in which volunteers were asked to perform word recognition exercises. The volunteers were monolingual and bilingual. Their blood flow was observed in order to measure how hard the brain was working during the tasks. According to Marian, the monolinguals had a harder time identifying the correct words because the bilingual brain is constantly choosing which language to use and which to ignore. The bilingual brain is better at inhibitory control, constantly filtering out irrelevant words, and in doing so, it provides the brain a built-in exercise.