Friday, August 10, 2012

How a Baby Learns to Talk Part II

This is the second part of a Science Friday series on how a baby learns to talk.  Check out the first post here.

     After practicing the formation of words through babbling, babies try to actually form words.  At 16 months, Q-ball is currently at this stage.  While we still have plenty of "eh! eh! eh!" noises when she wants to get our attention, she is starting to try to repeat words that she hears Daddy and I say.  With her active use of sign language, I can see that she is very eager to get her ideas across, so it makes sense that she wants to move beyond sign language to form words. 
   As stated in the first post of the series, humans are innately wired to create language.  Beyond this, scientists also believe that humans innately understand three critical ideas about words:
  1. Words refer to a whole object, not a specific part.  (So, Q-ball knows that "book" means the whole book, not just the cover or pages.)
  2. Words describe all like items, not just an individual item. (So, Q-ball knows that "book" does not just refer to the book that we read her before bedtime, but all objects with bound pages.)
  3. A object just has one name.  
Practicing the word "percussion"
  Admittedly, when I read these rules, I started thinking of exceptions, but I imagine that they are critical rules for language learning.  These rules also made me wonder how exactly Q-ball would define "milk", but now that she is also saying "Mama" regularly, I won't spend to much energy pondering this question.
   With these rules in mind, between 12 and 18 months, babies practice saying a few words here and there.  They may practice some words, and then not say them again for sometime. Interestingly, researchers seem to believe that "fifty is the magic number" when it comes to speaking.  Once a child can say 50 words, she starts to add words very rapidly- often adding multiple words in a single day!
   Why does this "explosion" of words happen?  Between 13 and 20 months, scientists have used electrical focal testing to discover that children's brains grow increasingly specialized to respond to words.  Early in this period, they use part of their cerebral cortex to distinguish between words and sounds that they know and those they don't.  But, by 20 months, toddlers begin to activate a more specialized area of the left parietal lobe, which is the part of the brain that stores word meanings.  It's remarkable to think of all of this happening in your precious, growing child!

     Here are a few more quick, fun facts about a baby's first words:
  • Most babies begin to understand the meaning of certain words (names, no, milk, etc) as early as 9 or 10 months.
  • At 12 months, the average child knows about 70 words.
  • At 12 months, the average child speaks 6 words.  
  • Once a child understands the meaning of a certain word, there is typically a 5-month delay until he can speak that word.
  • Between ages 2 and 6 years, it is estimated that children may learn up to 8 words in a single day. So, if you child is sleeping for 12 hours a day, that is more than one word every 2 hours!
   So, now that toddlers know all of these words, what happens next?  Check out a future Science Friday to learn about grammar learning in toddlers!
Eliot, L. (1999). What's Going on in There? Bantam Books: NY, NY.


  1. An interesting read, as usual. I had never come across those three rules before but, exceptions aside, they really would be useful in language learning!

    The whole thing about 50 being the magic number makes sense, too. Our pediatrician asked me at Annabelle's 18 month appointment how many words she had. I had no idea of an actual number, really, but she informed me that 50 was about average at age 2. I set out to list all of the words to satisfy my curiosity after, and I decided that she did have 50. I tried to keep the list up for a few days, but gave up when she started adding new ones so quickly that trying to keep record them all seemed silly. There was definitely an explosion right around that time!

  2. Interesting that you noticed the 50 word point- I've been wondering how accurate or noticeable it was.
    As far as the rules, the research does say that once a child understands one name for an object then they are able to easily adapt to knowing the names for the various parts of objects.


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