Assessment of children's receptive vocabulary using event-related brain potentials: Development of a clinically valid test

The combined verbal and motor impairments characteristic of children with disorders such as Cerebral Palsy (CP) frequently compromise the accuracy of standard psychometric assessments. What is needed is a test to measure language that does not require verbal or motor responses. This study was designed to determine whether single-word receptive vocabulary could be assessed in young children without CP, using an ERP-compatible test based on Form M of the Peabody Picture Vocabulary Test-Revised (PPVT-R). Fifteen 10-year-old children with normal levels of psychometric intelligence participated. Ninety pictures were selected from the PPVT-R (Form M), representing three levels of single-word receptive vocabulary (Preschool, Child-Adolescent, Adult). Each picture was presented twice (pseudo-random), once paired with a spoken word that was semantically congruent with the picture and once paired with a semantically incongruent word. The children's N400 was significantly larger to incongruent than to congruent pairs, but only when the vocabulary was within their repertoire. The results are discussed in terms of electrophysiologic correlates of acquired language and the clinical use of this ERP test as an adjunct to assessing patients with moderate to severe communication and/or motor impairments (e.g., cerebral palsy, autism, head injury).