An assessment of cerebral dominance in language--disordered children via a time-sharing paradigm

A time-sharing paradigm was used to assess language lateralization in language-disordered and normal children aged 4-7 years. Several expressive language tasks as well as a vocal, but nonlinguistic, task were administered concurrently with unimanual finger tapping. Dependent variables were percent disruption scores and number of syllables produced per concurrent trial. All language concurrent tasks produced tapping reductions for both hands for both groups. This result contrasts to similar time-sharing studies claiming asymmetrical interference and hence language lateralization in children (N. White & M. Kinsbourne, 1980, Brain and Language 10, 215-223; J. Obrzut, G. Hynd, A. Obrzut, & J. Leitgeb, 1980, Brain and Language 11, 181-194). A multiple regression analysis revealed a significant interaction effect differentiating language-disordered from normal children. Normals exhibited a parallel response pattern for speech and tapping (both increased or decreased in rate) under all lateralization conditions. Language-disordered children exhibited an inverse response pattern (e.g., if speech output increased, tapping rate decreased) only under left-hemisphere time-sharing.