Overgeneralization in the processing of complex forms in Valley Zapotec child language

Models of language learning and processing differ in their level of emphasis on the storage of individual meaningful units versus combinations of meaningful units. While there is evidence for the storage of larger stretches of speech, a separate issue is how much such stored forms contribute to processing, as compared to morphologically simpler forms. We examine the acquisition of one aspect of the phonology of Valley Zapotec: complementarity of segmental length based on subsegmental features: vowels before fortis consonants are short (VCː), and vowels before lenis consonants are long (VːC). This complementarity is found for fortis consonants in morphologically simple forms with final stress (simple nouns, verbs with full subject noun), but not in morphologically complex forms with a final unstressed syllable (diminutive nouns, verbs with pronominal subject clitic). During one period of development, Zapotec-learning children overgeneralize the complementarity from morphologically simple to morphologically complex forms (with u-shaped learning likely). The child’s processing of complex forms in language production is based more on simple forms than on the complex forms themselves. We identify five possible explanations of these results. Insofar as combinations of morphemes are stored at this young age, they are relatively ineffective at influencing processing during language production.