Agreeing when to disagree: A corpus analysis of variable agreement in caregiver and child English

We characterized the patterns of agreement variation and consistency in three corpora of child and child-directed US English to better understand preschoolers' input and to compare preschoolers' own agreement production. We examined sentences with third-person subjects and tensed forms of be in two large single-family corpora and one cross-sectional corpus collected during a Search-and-Find activity. Caregivers' agreement variation consistently reflected patterns previously found in adult-to-adult speech. Children's variation was conditioned by many of the same factors (e.g., sentence type, pronoun subject, and order of subject and verb) and clearly demonstrated acquisition of the categorical-variable split. However, some children showed substantially higher rates of nonagreeing forms (There's the cherries) than their caregivers and differed in their ranking of conditioning factors. We suggest that this reflects children's developing production processing abilities: shorter sentence-planning spans may make nonagreement a useful strategy for avoiding early number commitments in verb-first sentences.