Effects of articulatory planning factors on children's production of plural -s

Children’s early use of grammatical morphemes is notoriously variable. Recent findings indicate that some variability in early productions is systematically related to speech planning factors, suggesting that variability in morpheme production is not solely the consequence of impoverished syntactic representations. For example, research has shown that plural -s is produced more reliably in utterance-final compared to utterance-medial position. Here we examined the locus of the positional effect for plural -s . Productions of eight plural nouns in utterance-medial and utterance-final position were elicited from three groups of 2-year-olds. Across the groups, we manipulated articulatory difficulty of the medial context such that it consisted of a stop consonant (e.g., dogs bark), a stressed vowel (e.g., dogs eat), or an unstressed vowel (e.g., dogs arrive). Results showed a robust positional effect for the difficult context created by the stop consonant. The positional effect was not observed for the simple articulatory context created by the stressed vowel. However, planning difficulty for the unstressed vowel was sufficiently increased such that the positional effect again emerged in this context. These results suggest that production of grammatical morphemes is influenced by articulatory planning factors, which points to specific constraints for theoretical accounts of language acquisition.