How a Baby Learns to Talk: Part I

This is the first part of a Science Friday series that will focus on how a baby learns to talk.

    

   At 16 months, Q-ball is starting to babble and even talk a lot.  She's been saying "mama", "dada", "hot",  and a few other attempts at words for a few months now.  Recently, "uh-oh" was added and, she has loved practicing all of her animal noises.  And, in sign language, she is starting to put together two-word phrases ("diaper change," "more milk").  So, what, exactly is happening?  How does a baby learn to talk? 

   It turns out, it's a totally natural, instinctive process for humans.  Our brains are literally hard-wired with neurons (check out this old post for a brief overview of neurons) to understand and create language, just like any other daily task like seeing and hearing.  Scientists have concluded this for three reasons:

1. All children around the world have the same schedule for learning a language, whether it's English, Mandarin, or even sign language.  First, they learn single words, then two-word phrases, and then sentences.  
2. The brain has special neurons and centers completely devoted to language.  This was found when doctors started to document injuries that produced interesting changes in language (read about some here.)
3. Noam Chomsky has documented that all languages have a "Universal Grammar," that is, all languages have the same basic structure of noun, verbs, adjectives, and other parts of speech.  He concluded, then, that the human brain is structured to learn and create basic grammar rules.

Photo Credit: wikipedia.org

    However, even though learning a language is in a human's genes, it is life experiences that ensures it happens. There is a critical period for language learning. This is because children have far greater synaptic activity than adults (again check out this post if you want more details...) In some documented cases, children who are not exposed to language (sadly, many of these cases are due to abuse or neglect, but there is also a famous case in which the family did not realize their child was deaf until she was 32 years old) by about 6 or 7 years old, their lose their ability to master a language.  After this time, children may be able to learn a language, but they will not be as proficient as a native speaker.  And, in some cases, they may fail to ever learn to speak or sign at all. 

   Newborns possess an amazing ability to distinguish difference sounds.  Scientists have demonstrated that newborns can tell the difference between /pa/ and /ba/ and other similar sounds.  They can even tell the difference between foreign languages better than adults!  These amazing powers of newborns relate back to the theory that all humans will create language as our brains are literally hard-wired to do so.  Just talking to a newborn is the best way to activate his language learning capabilities.  

   Quickly, however, the brain starts to favor the language with which it is most exposed.  As time goes on, children lose the ability to distinguish the fine differences between phonemes and, thus, languages. 

   Beyond listening to other speak, babies also learn language by practicing it themselves.  They babble!  We may think that talking is pretty easy, but it requires lots of motor coordination. Babbling is a baby's way of exercising and experimenting with his tongue, lips, palate, and larynx. During this time, babies are actually undergoing physical changes as well. At birth, a human's vocal tract looks more like an ape's than a humans.  By six months, however, it has started to take a more human shape.  A baby's babbles reflect the language and even accent that he hears.  In one experiment, when a 12-month old was exposed to a female speaker for 15 minutes, he actually started to change his pronunciation to match hers! 

  So, what happens after babbling?  Actual words!  Come back soon to read more about the science of a baby's first words.

Source:
Eliot, L. (1999). What's Going on in There? Bantam Books: NY, NY.