Separating visual perception and non-verbal intelligence in children with early brain injury.

The relationship between impairments of visual perception and of non-verbal intelligence was studied in 28 children who, due to the nature of their neurological pathology, were at risk for visual perceptual impairments (high-risk), and 18 mentally disabled children without such risk (low-risk). Their age range was 3-14 years. A child was considered specifically visual-perceptually impaired (VPI) if performance on the De Vos task, a visual object recognition task, was weaker than expected from the baseline performance level obtained on non-verbal intelligence subtests. Accordingly, 22 high-risk children (79%) were classified VPI, against only four low-risk children (22%). Comparing intelligence data of children with and without VPI revealed a WPPSI non-verbal to verbal intelligence impairment in the former. At the subtest level, comparing five verbal and five non-verbal WPPSI subtests, and five subtests from the Snijders-Oomen non-verbal intelligence scale, revealed a difference only on Animal House. The absence of any systematic effects of specific visual perceptual impairment on intelligence subtest performance leads us to conclude that in these children VPI and selective non-verbal intelligence impairment coexist as two separate and irreducible deficits.