The Concise Encyclopedia of Applied Linguistics

FFirst Language Vocabulary Acquisition

EVE V. CLARK

Children produce their first words anywhere between 12 and 24 months of age. And they add steadily to their vocabulary from then on, at a rate estimated at around nine words a day up to age 6 (Clark, 2016). However, children understand more than they can produce, so measures of early vocabulary acquisition assess both comprehension and production (e.g., Fenson et al., 1994). Moreover, this comprehension/production asymmetry is lifelong: speakers of a language consistently understand more varieties than they can produce, and so have a comprehension vocabulary that surpasses what they use themselves in production (Clark & Hecht, 1983). Some researchers have noted a “spurt” in word production where children aged 1;8–1;10 start to produce more new words per week than in preceding months. However, as McMurray (2007) showed, this apparent spurt does not result from children starting to learn a larger number of words at this point, but rather from increases in their articulatory skill that allow them to add new words with less practice as they get older. Lastly, neurological studies show that as children become familiar with specific words in their first two years, they show greater left hemisphere activation for them. In contrast, unfamiliar words show activation in both hemispheres (e.g., Mills, Plunkett, Prat, & Schafer, 2005).

How many words are children aiming for? In English, adult vocabulary size has been estimated at between ...