Another look at VIQ-PIQ scores and unilateral brain damage.

The relationship of WAIS, VIQ, PIQ and Aphasia Screening scores to unilateral brain damage was investigated using 18 subjects with left hemisphere damage (LHD) and 19 subjects with right hemisphere damage (RHD). Expected VIQ-PIQ difference scores were demonstrated only for the RHD subjects. Aphasia was significantly associated with PIQ in the LHD group. ANCOVAR using Aphasia Screening as a covariate produced significant LHD versus RHD differences on PIQ. These data question the utility of VIQ-PIQ difference scores in the diagnosis of unilateral brain damage. Second, the data suggest that LHD "non-verbal" deficits are the result of underlying language disturbance and not the consequence of impaired visuoperceptive or visuospatial processes.