A hierarchical analysis of block design errors in children with early focal brain damage

This study investigated the differential effects of very early damage to the left hemisphere (LH) or right hemisphere (RH) on visuospatial processing. Twenty-two children who had suffered either LH or RH strokes in the pre- or perinatal period were included in the study. The Block Design subtest of the Wechsler Intelligence Scale for Children-Revised (Wechsler, 1974) was used. Each missed item was coded as either a global error (e.g., broken configuration), local error (e.g., incorrect details), or time fail error (i.e., not completed within the allotted time). Results showed that the LH lesion and RH lesion groups had similar full scale IQs, verbal IQs, and performance IQs and were within the average to low average range. Block Design scaled scores were also within the average to low average range and did not significantly differ between the 2 lesion groups. Error analysis revealed, however, that the RH focal lesion group produced a significantly higher percentage of global errors than did the LH lesion group, whereas the LH lesion group produced a significantly higher percentage of local errors than did the RH lesion group. The groups did not differ on their percentage of time fail errors. These results are consistent with previous findings that suggest that the RH is involved in more global aspects of visual processing, whereas the LH mediates the more detailed, local aspects of visual information. The fact that these differences in processing are present after such early focal damage implies that hemispheric specialization for visuospatial processing occurs very early in brain development.