Verbal-Motor Behaviour in Adults With and Without Down Syndrome

Abstract

Previous research has indicated found that individuals with Down syndrome (DS) have difficulties in processing auditory information for the planning of movements relative to their peers with undifferentiated developmental handicaps. This modality-specific information-processing difficulty has been found for the preprogramming of goal-directed aiming movements (Le Clair & Elliott, 1995) and in simple reaction times (Davis, Sparrow, & Ward, 1991; Hermelin, 1964). The purpose of the present study was to assess whether or not a model of atypical cerebral specialization for the perception of speech sounds, proposed by Elliott and colleagues, could explain these findings. Thus, participants performed a choice reaction aiming task under three conditions. Colour-coded targets were cued by a visual cue at the target location, a visual cue remote from the target location, or a verbal cue identifying the target. Results revealed that while the reaction times did nCit differ between the two groups with handicaps, the participants with DS, unlike the two control groups, had significantly longer movement times in the verbal than in two visual conditions. These results support the model of biological dissociation.