Oral language in individuals with nonverbal learning disabilities (NLD) has been described as empty of meaning, despite apparently average word knowledge. The present study explored the hypothesis that depth but not breadth of semantic representations would be reduced in NLD, and that depth but not breadth would be related to nonverbal gestalt perception. A cross-sectional design compared breadth and depth of vocabulary in 50 adults with or without a diagnosis of NLD. Vocabulary results were also compared with a visual closure test. Participants with NLD had reduced vocabulary depth in comparison with controls. The NLD group also had lower scores for gestalt perception, the ability to perceive a meaningful whole from unrelated parts. Across the sample, this measure predicted scores for vocabulary depth, but not breadth. The NLD group was also less able than the Control group to estimate the size of unknown, physical features of everyday objects. Results supported clinical observations that semantic representations are unconventional and imprecise in individuals with NLD, and suggested specific cognitive underpinnings for such difficulties. Results were also compatible with separate theories of embodied and lateralized semantics. A proposal uniting these theories in a designation over elaboration model is presented.

As a group, children with myelomeningocele (MM) and early-onset hydrocephalus demonstrate many of the features of the syndrome of nonverbal learning disabilities (NLD). However, the frequency with which individual children display a pattern of neuropsychological functioning consistent with the NLD syndrome is unknown. We addressed this question by comparing the prevalence of NLD in 32 children with MM and shunted hydrocephalus to that in a group of 27 healthy siblings. Participants, who were between 8 and 15 years of age, completed a neuropsychological test battery that included 11 measures of possible assets and 17 measures of possible deficits that define the NLD syndrome. As a group, children with MM and shunted hydrocephalus displayed many of the specific assets and deficits. However, they also displayed significantly more variability in their patterns of assets and deficits than siblings, reflecting the substantial individual differences that characterize children with MM. About 50% of the children with myelomeningocele displayed a pattern of assets and deficits consistent with the NLD syndrome. Classification as NLD was weakly related to cumulative medical risk, as well as to left-handedness. The findings suggest a need for caution in making generalizations regarding the applicability of the NLD model to children with MM and early-onset hydrocephalus. (JINS, 2003, 9, 653–662.)