In 2016 Naja Ferjan Ramirez, of the Institute for Learning & Brain Sciences (I-LABS) at the University of Washington, performed a study comparing 11 month old babies exposed to English only with babies exposed to Spanish and English in their homes. “Our results suggest that before they even start talking, babies raised in bilingual households are getting practice at tasks related to executive function. This suggests that bilingualism shapes not only language development, but also cognitive development more generally,” she said.
In the same study the team of researchers found that introduction of the second language early is most beneficial. “Our results underscore the notion that not only are very young children capable of learning multiple languages, but that early childhood is the optimum time for them to begin,” the lead researcher said.
In another study published in the Journal of Phonetics by Adrian Garcia Sierra also indicated that early exposure to a second language is beneficial. The study suggested that "the bilingual brain remains flexible to languages for a longer period of time, possibly because bilingual infants are exposed to a greater variety of speech sounds at home" Therefore, exposing an infant to another language early will make the brain more receptive to learning another language.
"The bilingual brain is fascinating because it reflects humans' abilities for flexible thinking -- bilingual babies learn that objects and events in the world have two names, and flexibly switch between these labels, giving the brain lots of good exercise," said Patricia Kuhl, co-author of the study and co-director of the UW's Institute for Learning & Brain Sciences.
Every little bit of exposure helps. Do not be discouraged if your child speaks only English back to you as they start speaking. Those tiny connections in the brain will be stimulated when they hear Spanish words. Keep introducing Spanish as much as you can every day. As these studies have found, earlier is better.......