Principal identifying features of the syndrome of nonverbal learning disabilities in children.

The identifying features of the syndrome of nonverbal learning disabilities (NLD) were examined with a view to determining their relative discriminant validity. A stepwise linear discriminant function analysis of children with NLD (n = 29), children with reading and spelling disabilities (Group R-S; n = 27), and a group of nonclinical children (NC; n = 27) on 15 neuropsychological variables yielded a subset of scores on four tests (Target Test; Trail Making Test, Part B; Tactual Performance Test; and Grooved Pegboard Test) that accurately (> 95%) discriminated the NLD group from the R-S and NC subjects. Of the neuropsychological features of NLD described by Rourke (1987, 1988b, 1989), deficits in visual-perceptual-organizational psychomotor coordination and complex tactile-perceptual skills appeared to be most representative (in the sense of most discriminative) of the NDL syndrome in the children examined. These are also the dimensions that are considered to be "primary" in the NLD model (Rourke, 1989). Replication of these results, employing children with other clinical disorders, is necessary.