The studies

Variability and Consistency in Early Language Learning: The Wordbank Project

A main source for the ages

Variability and Consistency in Early Language Learning: The Wordbank Project

Michael C. Frank, Mika Braginsky, Daniel Yurovsky, Virginia A. Marchman · 2021 · MIT Press

Children
About 82,000 word lists filled in by parents
Where
29 languages, mostly from Europe and the United States
Ages
8 to 30 months
How
Researchers pooled parents' word lists from many studies (the Wordbank collection)
What it found
Gives "around one year" as a rule of thumb for first words, and shows that children of the same age vary a lot in how many words they say.
Limits
Parents can miss words or count babble as words. Most children were from Europe and the United States and learning one language.

Read the original study

Pages that use this study

We describe every study in our own words. How we choose and check studies