In spite of the new interest in NLD as a diagnosis, speech and language skills in this population have remained largely unexplored, at least in any systematic way. Anecdotal accounts are virtually the only sources of information at this time. Research establishing empirical bases to support existing clinical descriptions is greatly needed. Language often is divided into the domains of form, content, and use. Three dimensions of language structure—phonology, morphology, and syntax—are included in the broader domain of language form. Phonology, which includes mastery of the sound system, is reported to be intact in children with NLD. The dimension of morphology, which deals with inflectional word marking, also is reported to be adequate. Likewise, syntax, including the formation of complete sentences and the use of various sentence types, is described as age-appropriate. Although none of these dimensions have been subject to detailed empirical examination, case reports and anecdotal accounts report no stark deficits as judged by conversational partners. Thus, while evidence would be useful for validating clinical impressions, it seems likely that language structure is not an area of dysfunction for these children.
The status of language content, or semantics, is less clear. Children with NLD, for example, may exhibit large and sophisticated vocabularies. Being able to use a large number of sophisticated words, however, does not automatically ensure that children fully understand them. For example, one young adult in one of the research on NLD was engaged in a referential communication task where she was required to describe a certain geometric shape. She described it as "a unilateral triangle." While it's possible she could have confused the isosceles triangle on the stimulus card for an equilateral triangle, it was definitely not a single-sided shape as the word "unilateral" denotes.
Ultimately, says Rourke, "although children with NLD tend to be verbose, there is relatively little in the way of meaningful content that is conveyed in their discourse". Others have described this phenomenon as "cocktail party language."
Difficulties in comprehension become more apparent as the child grows older, and conversational interactions begin to demand the ability to employ contextual cues. In addition, the appreciation of humor, irony, idioms, or metaphor requires an adept manipulation of literal and literary meanings. This requires elaborated semantic networks that allow for a word to be connected with a variety of concepts. With only a superficial understanding of language, the child with NLD is unlikely to appreciate figurative language or abstract meaning. A child with NLD, who was told to "watch your hands" when using scissors, proceeded to stare at his fingers.
One explanation for relatively superficial semantic knowledge is the over-reliance that these children apparently place on learning through auditory and verbal means. Perhaps many of the words of the child with NLD are "fast mapped" rather than fully understood. This too is a reasonable area for systematic research.
The most deficient domain of language in children with NLD is reported to be language use or pragmatics. Pragmatics refers to the appropriate social use of language and includes the ability to generate language to accomplish a wide variety of specific social purposes (e.g., requesting objects, requesting information, commenting, greeting, etc.) as well as the ability to manage conversations successfully (e.g., initiating interactions and introducing topics, taking turns, maintaining and building on topics, recognizing and repairing conversational breakdowns, etc.).
Again, none of these areas has been the subject of empirical investigation but, in anecdotal accounts, it is the discourse skills or conversational management abilities of children with NLD that are reported to be seriously impaired.
In addition, speakers with NLD are often described as verbose. Other examples of pragmatic difficulties that may occur include frequent use of stereotyped expressions such as "by the way" or "actually," an inability to read or use facial expressions or tone of voice, difficulties in using facial expression and gestures to express feelings, problems with appropriate speech prosody resulting in a lack of affective modulation in language, and abrupt topic shifts.
At present, at least in terms of speech and language symptomatology, the descriptions of NLD bear considerable similarity to those associated with a variety of other conditions, such as semantic-pragmatic disorder, pragmatic language impairment, high-functioning autism, Asperger's syndrome, and others. It is possible that what is described in educational terms as nonverbal learning disability may be what we describe in speech-language terms as pragmatic language impairment.
The attached "Descriptive profile of children with Nonverbal Learning Disabilities" provides a compilation of the characteristics of children thought to have this problem. It was culled from an extended review of the literature.
Because our knowledge about these children is incomplete, this Profile should be used with caution. Some children with some of the characteristic in the Profile may not suffer from Nonverbal Learning Disabilities. It is also possible that some children with Nonverbal Learning Disabilities may not fit many of the characteristics described in the Profile.
The attached "Descriptive profile of children with Nonverbal Learning Disabilities" provides a compilation of the characteristics of children thought to have this problem. It was culled from an extended review of the literature.
Because our knowledge about these children is incomplete, this Profile should be used with caution. Some children with some of the characteristic in the Profile may not suffer from Nonverbal Learning Disabilities. It is also possible that some children with Nonverbal Learning Disabilities may not fit many of the characteristics described in the Profile.