Do all Toddlers have Word Explosions?

If you're a parent or therapist working with toddlers, you've probably heard the term 'language explosion' or some iteration of it (e.g. word burst, word spurt, word explosion). This 'language explosion' is observed in most toddlers once their productive vocabulary reaches roughly 50 words - this happens at around 18 months old, on average (Nelson, 1973). At this time, language is observed to 'take off' at a rapid rate, with toddlers acquiring new words at remarkable speeds. Sometimes, these language 'spurts' or 'bursts' can be small (e.g. Child 1) or quite dramatic (e.g. Child 2). But for other children, vocabulary growth is observed to be more gradual, in nature (e.g. Child 3).

Some researchers believe that this 'language explosion' is the result of a shift in word learning efficiency helping to catapult the acquisition of new words (Hoff, 2005). Other researchers, however, argue that this 'explosion' is a myth and that word learning for all children is actually more steady (Bloom, 2000). Whatever the argument, one thing remains clear: vocabulary growth is not always linear, nor is it predictable. The trajectory of a child's expressive vocabulary is unique to them and may be impacted by how listeners track and categorize new words (but that's a discussion for another day!). See for instance, the trajectories of the three children below. All three of this children are meeting their language milestones, but their trajectories look quite different. (I've been asked if these represent my three kids and no, these are just examples! How cool would that be, though?).

My point is this: As long as your child is meeting language milestones, the speed with which they are acquiring new words does not matter. So comparing the size of your child's vocabulary to another child's vocabulary is unproductive and will likely cause you to second guess what is 'normal'. Children start with their own unique vocabularies and they grow based on a whole host of factors: environments, caretakers, native language, and more. Your child is unique. No two vocabularies will ever be identical.

So how does this relate to late talkers? For some children who are late-to-talk, we see a 'language explosion' much later. For my own son (a late talker), we saw a spurt at around 22 months. He had not met his expressive language milestone at 18 months, but later met the milestone at 24 months. For many late talkers, word learning continues to be gradual. These children may need support in adding new words and may need support in beginning to combine words.

Word learning is highly individual. It is not a race to the finish line.

If you’re concerned about your child’s expressive language skills, it is best to get an evaluation with a Speech-Language Pathologist. He or she will be able to discuss language milestones with you and how you can support your child in their vocabulary journey.

References:

Bloom, P. (2000). How children learn the meanings of words. MIT Press.

Hoff, E. (2005). Language Development (4th ed.). Wadsworth/Thomson Learning.

Nelson, K. (1973). Structure and strategy in learning to talk. Child Development in Publications University of Chicago Press.