The acquisition of the English plural morpheme by native Mandarin Chinese-speaking children.

Although the acquisition of the English plural morpheme by monolingual English-speaking children (L1 learners) has been studied extensively, little is known about the processes through which native speakers of other languages (L2 speakers) acquire the English plural morpheme. To understand the similarities and differences between L1 and L2 English plural morpheme acquisition, 10 native Mandarin-speaking children who immigrated to the United States between ages 5 and 16 years were followed for 5 years. Their proficiency in English plural morpheme production was measured by a picture description task and by their spontaneous speech. In contrast to L1 learners who master the plural morpheme within 3 years of age, only 7 of these 10 L2 learners did so after 5 years of English exposure. Age of initial exposure to English and language environment explained individual differences to some extent. Participants' speech illustrated all error types made by L1 learners; however, L2 learners more frequently marked the same noun inconsistently in the same testing session, and more often overgeneralized the plural morpheme in singular or mass noun contexts. Differences between L2 learners and L1 learners with specific language impairment are also discussed.