The science behind your child’s ‘language explosion’

Dog! Bus! Cup! Is your toddler surprising you with all the new words they can say? If not, they likely will soon ❤️

Many children experience a large increase in spoken vocabulary between 18 and 24 months. Your child has been working hard to understand language since they were born. During their first year, they learned how to distinguish sounds and combine those sounds. Their words came slowly at first. At some point, all the pieces fall into place, and they start to say as many as 10 new words each week. 

3 reasons for a big increase in spoken words

The language explosion is still a bit of a mystery to researchers, but recent studies suggest that this exciting developmental phase happens when:

1. Your toddler learns words in parallel

Initially, your child learns just one word at a time. Once they’ve collected enough of these individual words to form a solid foundation in their brain, they start picking up multiple words at the same time.

2. They hear the right ratio of “easy” and “hard” words

Your child’s brain is actually doing some complex statistical work to figure out which word sounds they hear most often. They learn “easy” words—dog, cat, ball—first because they hear them a lot. Research shows that once they know about 50 simple words, “difficult” words—like rainbow or peacock—become easier to pick up.  

3. They start “fast mapping”

Imagine there’s an apple, a cup, and a banana in front of your toddler. Even if your toddler doesn’t know the word for “banana,” they may be able to point to it if they already know the words “apple” and “cup.” This process of elimination helps your child pick up new words quickly. Language experts call it “fast mapping.” 

Can you encourage the ‘language explosion’?

Research suggests that the vocabulary explosion can be encouraged but not rushed. Like most skills, language learning happens in stages. As long as your child is exposed to lots of words every day, their vocabulary will eventually take off.

If your toddler hasn’t experienced a language explosion yet, keep doing all the things you typically do to bring language into their daily life—for example, label objects they show interest in, narrate what’s going on around them, and read lots of books. If you’re concerned about your child’s language development, talk with their pediatrician. 

Learn more about the research

Kuhl, P. K. (2004). Early language acquisition: Cracking the speech code. Nature Reviews Neuroscience, 5(11), 831-843.

McMurray, B. (2007) Defusing the childhood vocabulary explosion. Science, 317(5838), 631.

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