Examination of the locus of positional effects on children’s production of plural –s: considerations from local and global speech planning

Purpose: Prosodic and articulatory factors influence children’s production of inflectional morphemes. For example, plural –s is produced more reliably in utterancefinal compared to utterance-medial position (i.e., the positional effect), which has been attributed to the increased planning time in utterance-final position. In previous investigations of plural –s, utterance-medial plurals were followed by a stop consonant (e.g., dogs bark), inducing high articulatory complexity. We examined whether the positional effect would be observed if the utterance-medial context were simplified to a following vowel. 

Method: An elicited imitation task was used to collect productions of plural nouns from 2-year-old children. Nouns were elicited utterance-medially and utterancefinally, with the medial plural followed by either a stressed or an unstressed vowel. Acoustic analysis was used to identify evidence of morpheme production. 

Results: The positional effect was absent when the morpheme was followed by a vowel (e.g., dogs eat). However, it returned when the vowel-initial word contained 2 syllables (e.g., dogs arrive), suggesting that the increased processing load in the latter condition negated the facilitative effect of the easy articulatory context. 

Conclusions: Children’s productions of grammatical morphemes reflect a rich interaction between emerging levels of linguistic competence, raising considerations for diagnosis and rehabilitation of language disorders.