Level-ordering does not constrain children's ungrammatical compounds.

English-speaking children typically avoid using regular plurals in novel grammatical deverbal compounds as in rat eater but allow irregular plurals as in mice eater (Gordon, 19985). To explain these data, it has been argued that level-ordering model constrains the production of morphologically complex words, including those with which children have had little to no experience. If level-ordering can be supported, children should avoid regular plurals in their ungrammatical deverbal compounds like a breaker-bottle. Seventy-two English-speaking children were included in the present study, 36 from Britain and 36 from Canada. The results showed that 50% of the children who produced ungrammatical compounds included regular plurals in the compounds they produced. Conversely, none of the children who produced grammatical compounds included regular plurals. These results indicate that level-ordering does not constrain children's production of ungrammatical compounds. These results raise the possibility that level-ordering may not be a valid constraint of children's compounding in general.