The evidence keeps pouring in that bilingualism is good for you.

Bilinguals with the ability to switch languages seamlessly have likely developed a higher level of mental flexibility than people who only speak one language, researchers at Penn State said Tuesday in a press statement.

“In the past, bilinguals were looked down upon,” Professor of Psychology, Linguistics and Women’s Studies Judith F. Kroll said in a press statement. “Not only is bilingualism not bad for you, it may be really good. When you’re switching languages all the time it strengthens your mental muscle and your executive function becomes enhanced.”

Researchers performed two experiements on English and Spanish speakers to assess whether both languages were active in their minds at all times. In the first, subjects read 512 sentences in either English or Spanish, switching between the two every two sentences, and had to read cognates out load in red as quickly and accurately as possible. The subjects rarely tripped up. The linguists then performed the same experiment, one language at a time, with similar results.

“Bilinguals rarely say a word in the unintended language, which suggests that they have the ability to control the parallel activity of both languages and ultimately select the intended language without needing to consciously think about it,” the release says.

The researchers published the results of the experiments in Frontiers in Psychology.

The study is part of a growing body of evidence upending the traditional view that growing up bilingual hindered cognitive development.

But not everyone is getting the message. The school board of Irving, Texas, is moving to limit the use of Spanish in the district’s bilingual education. Arizona voters banned bilingual education in the year 2000.