Exceptional Rule Learning in a Longitudinal Case Study of Williams Syndrome: Acquisition of Past Tense

Conflicting reports of language ability in Williams syndrome (WS) are confusing and may hinder accurate clinical decisions with respect to therapeutic services and educational placements for children with WS.This longitudinal case study examined the acquisition of regular and irregular past tense verbs in a child with WS. The development of regular and irregular verbs was monitored using an elicited production task, supplemented with informal language samples and a grammaticality judgment task. The authors found an unusual profile of regular and irregular past tense use that both approximated and diverged from normal expectations at various stages. The unusual pattern of past tense acquisition is presented in its relation to other language problems known with regard to WS. Clinical implications for assessment and intervention are discussed. (Contains 4 tables.)