You know that feeling when you get tongue-tied and words just come out as a mess?  Maybe you forget a word or have mushy grammar or your pronunciation is all wrong.  There are a lot of things to keep track of.  It seems like learning one language would be hard enough for babies, who already have trouble eating and not spitting up everywhere, but research has shown that infants are a lot more capable than you might think, especially when it comes to language.

In fact, a lot of babies from bilingual families grow up fluent in both languages.  Many psychologists think language is what's called an innate ability, or something we're born knowing how to do, like grasping objects and sucking on things -- classic cute baby stuff.  So right from the start, babies are primed to learn a language, any language.  Most of us adults have trouble hearing subtle inflections in foreign languages, like if you only speak English it might be hard for you to hear the difference between certain sounds in Thai or Russian, but in their first few months of being alive, babies can tell really similar sounds apart.

To figure this out, lots of researchers have done studies where they pick a sound from a foreign language and play it on loop for babies around four months old.  When the babies lose interest, the researchers switch to a new, similar sound.  Usually, these really young infants notice the difference and perk up somehow, like by looking around or sucking harder on a pacifier, but if scientists repeat this experiment around eight months later, one-year-old babies typically ignore the second sound because they don't notice a difference.

That's probably because as they get older, their brain cells make connections that help them focus on the sounds of their native language, and they get rid of unused connections related to recognizing other sounds.  So, by the time an infant is one year old, its brain is already focusing on learning whatever language it's been exposed to most.  And surprisingly, babies don't need any special training to be bilingual, but they need equal exposure to both languages.

Now, you might have heard that bilingual kids develop more slowly to their monolingual counterparts or are more likely to have speech delays, but according to the research, that's just not true.  That even applies to babies who grow up with one spoken and one signed language, like English and American Sign Language.  As they get older, these kids keep their languages separate thanks to their awesome perception skills.  Just by watching faces and listening to verbal patterns, they're able to figure out when they should be speaking which language by around the time they're three years old.

When they intentionally switch from speaking one language to another, like talking to their friends in English but their mom in Cantonese, that's called code-switching.  Now, even though monolingual and bilingual babies develop at the same rate, one study from the University of Washington suggested their brains processed language a little differently.  Psychologists used electroencephalograms, also known as EEGs, to detect brain activity in some six-month-old monolingual and bilingual babies as they played recordings of speech sounds in English and Spanish.  Babies in EEG caps?  Super adorable.

They found that monolingual babies caused a spike on the EEG whenever a mismatched sound popped up, like a Spanish sound thrown in among a bunch of English sounds or vice versa, which means they noticed a difference.  But bilingual baby brains didn't notice when the languages switched.  When the same babies were ten to twelve months old, though, the results changed.  The monolingual baby brains only responded when a sound in their native language interrupted a string of foreign sounds but not the other way around, and the bilingual babies went from not noticing a difference to hearing both kinds of mismatches.

According to the researchers, this means that monolingual baby brains seem to solidify connections faster to get ready to speak their primary language, but the bilingual baby brains stayed more flexible and didn't develop that wiring until later on.

Turns out that this flexibility can have some developmental perks too.  One study published in the journal Science found that bilingual babies may be better at learning rules and switching between them than monolingual babies.  In the study, one-year-old infants were taught that when they heard a certain pattern of sounds, they should look at a specific spot on a screen to see a fun toy.  When the psychologists changed the pattern and moved the toy picture, the bilingual babies were better at figuring out the new rules and looking for the toy in the right places.

Multiple studies suggest that bilingual adults have similar benefits, like better focus and ability to switch between tasks, and even less cognitive decline when they get older.

But this doesn't mean that all hope is lost if you're not bilingual -- it's just one path a human brain can take.  Our brains are really powerful, and even when you weren't a tiny adorable baby you were a lot smarter than you might think.

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