When children have problems with words, their problems may hit some types of words harder than others. A number of studies of language-impaired children have exposed verbs as an area of particular difficulty.

One study involved an extensive comparison of the words and structures used by a group of language-impaired children and a group of normally developing children (Fletcher & Peters 1984). The two groups were of similar age and non-verbal intelligence. Each child's language was sampled in four different activities: free play with toys, talking about pictures in a book, playing a board game, and re-telling a story about a set of pictures. Each sample consisted of 200 utterances, 50 from each activity. The samples from the two groups of children were then compared in terms of a wide range of lexical and grammatical categories. This revealed that the vocabulary of the language-impaired children was generally more restricted than the vocabulary of the normally developing children, and significantly, the verb range of the languageimpaired children was especially limited.

Similarly, in a study focusing on verb use, it was found that a group of fourteen language-impaired children had a narrower range of verbs than normally developing children matched in age (Watkins, Rice & Moltz 1993). Even more striking, though, was the comparison between these language-impaired children and a group of normally developing children who were nearly two years younger than them, but at the same general language level. The verb range of the language-impaired group was still more limited than that of the control group, even though their vocabularies as a whole did not differ significantly.