The Role of Frequency in Learning Morphophonological Alternations: Implications for Children With Specific Language Impairment
Purpose: The aim of this paper was to explore how the type of allomorph (e.g., past tense buzz[d] vs. nod[əd]) influences the ability to perceive and produce grammatical morphemes in children with typical development (TD) and with Specific Language Impairment (SLI). Method: The participants were monolingual Australian-English-speaking children. The SLI group included 13 participants (mean age=5;7); the controls were 19 TD children (mean age=5;4). Both groups performed a grammaticality judgment and elicited production task with the same set of nonce verbs in 3rd person singular and past tense forms. Results: Five-year-olds are still learning to generalise morphophonological patterns to novel verbs, with syllabic /əz/ and /əd/ allomorphs significantly more challenging to produce, particularly for the SLI group. The greater phonetic content of these syllabic forms did not enhance perception. Conclusions: Acquisition of morphophonological patterns involving low-frequency allomorphs is still underway in TD 5-year-olds, and is even more protracted in SLI population, despite these patterns being highly predictable. Children with SLI will therefore benefit from targeted intervention with low-frequency allomorphs.