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Question #5


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Questions and Answers

 

Question # 5

Why is there so much emphasis on nonverbal in NLD?
Does this mean that persons with NLD have well-developed language?
In what sense is the language of persons with NLD deficient?
How can one characterize the relatively intact and defective linguistic characteristics of persons with NLD?


It is clear that persons with NLD exhibit a variety of significant linguistic deficits. Within the NLD model, however, these are seen as the result of primary, secondary, and tertiary NLD (i.e., decidedly non-linguistic) deficits (see Figure 1).

There are several issues to address with respect to these questions. These are discussed within the context of specific and general dimensions, as follows (see Rourke & Tsatsanis, 1996, and Rourke, van der Vlugt, & Rourke, 2002) for a fuller explanation of these and related issues).

Specific Considerations

It is usually observed that, following an initial delay in speech acquisition, children with NLD go on to exhibit some well-developed speech and language skills. There is, however, comparatively little appreciation of the full extent of their deficits in linguistic skills. The NLD syndrome is so-named because all of its "clinical" presentations (including problems with some important dimensions of language) are thought to arise from deficits that are primarily nonverbal in nature. The psycholinguistic dimensions of NLD that constitute integral features of its developmental picture are thought to arise because of the primary, secondary, and tertiary assets and deficits outlined in the model (see Figure 1).

It is clear that a superficial consideration of the speech and language of children with NLD would be misleading; there is a great deal to be understood through close examination of the qualitative aspects of their linguistic skills. With these observations as background, the following specific considerations are offered.

(1) The language of persons with NLD is not "good." Indeed, the language of such individuals is typically moderately to severely deficient in content and pragmatics. Verbosity that does not convey much meaning (content) and which is lacking in relevance to the question or task at hand (pragmatics) is hardly "good" language. (See below for a more extensive explanation of differences between linguistic form, content, and pragmatics.) Added to these deficits is the lack of prosody in the linguistic utterances of such individuals. Deficiencies in prosody not only contribute to lackluster speech, they can also detract from meaning--thus, further limiting the content/substance of communication.

(2) The language of persons with NLD is "good" only in the sense that it tends to be high in quantity. The linguistic deficiencies of such individuals become apparent only when one examines the quality of their verbal productions.

(3) The tendency for persons with NLD to attend and respond to the phonological aspects of language rather than to their semantic dimensions is a limitation that can further complicate communication. A moment's reflection will reveal that misinterpretations of messages from others could, potentially, be legion if this state of affairs obtains.

(4) The language of persons with NLD is usually delayed initially. Although all developmental milestones--including those related to language--tend to be delayed in youngsters with NLD, some language milestones tend to be delayed less than those in other areas (e.g., psychomotor coordination). This has the tendency for drawing parental and other caregivers' attention to the language of the youngster with NLD (unconsciously, perhaps, resolving their cognitive dissonance vis-a-vis the child), with the unfortunate by-product of a tendency to disregard other important dimensions of the child's development (e.g., motor/psychomotor; visual-spatial) that would bolster the notion that the child is significantly delayed or deficient in developmental skills.

(5) Some aspects of language and language-related skills do, in fact, become well-developed in persons with NLD. An obvious example is handwriting which, although very poor initially (ages 5 through 8), usually becomes quite good at a later stage of development (adolescence). Indeed, this is an example of a more general principle relating to the NLD syndrome, namely, that skills that lend themselves to increased performance with rote overlearning are those that persons with NLD can and do "learn."

(6) The neuroanatomy/physiology of language development is also of relevance in this connection. It would appear that relatively little communication via white matter tracts between the three principal opercula of the left hemisphere is required for the development of those language skills exhibited by the person with NLD. In this connection, it may be the case that the failure to develop this minimal level of white matter communication tracts is responsible for the severe language problems exhibited by children with early and diffuse perturbations of white matter.

General Considerations

This discussion of the psycholinguistic dimensions of NLD is presented within the context of a framework developed by Bloom (1988) who has described language as consisting of the three basic dimensions of form, content, and use. We (Rourke & Tsatsanis, 1996) have proposed the following with respect to the three principal dimensions of language as exhibited by persons with NLD: Form (normal) > Content (moderately impaired) > Function (severely impaired).

Language form refers to the structure of language; it is comprised of three dimensions in particular -- phonology, morphology, and syntax. A conventional system for combining sounds to produce words to yield sentences is entailed in language form. The processes by which these units are connected are rule-governed and thought to develop in a systematic and automatic manner (Bloom, 1988; Boone & Plante, 1993).

Children with NLD demonstrate a facility with the structure of language. These children are noted to display well-developed rote language skills and they experience little difficulty with the phonological and basic syntactic aspects of language. They exhibit good auditory perception and generally advanced phonemic encoding and decoding, segmentation, and blending skills. In addition, errors in reading and spelling are almost always of the phonetically accurate variety. In general, children with NLD are inclined to automatize language and are likely to experience less difficulty with dimensions of language that are structured or easily routinized.

Language content refers to what people talk about: ideas about objects and events in the world (and the relations between them) that are coded by language (Bloom, 1988). Content also refers to the manner in which meaning is attached to words and how these words are used to convey meaning to another person. It includes domains such as semantics and lexicon.

Two characteristic features of NLD lend the appearance that these children have facility with language content: (a) a high volume of speech output and (b) well-developed vocabulary and word-recognition skills. Because children with NLD exhibit strong verbal memory skills, they are often able to recall a plethora of facts and details and to repeat verbatim segments of prose with little difficulty. These children are observed to display a large store of verbal material and verbal associations. However, although children with NLD tend to be verbose, there is relatively little in the way of meaningful content that is conveyed in their discourse. Rather, their speech is inclined to be straightforward, repetitive, and rote.

Language function (or pragmatics) refers to the functional and contextual aspects of language. This includes an appreciation of the rules of social discourse, the speaker's purpose/intent for communication, and how language is modified to fit different situations (Bloom, 1988; Boone & Plante, 1993). Children with NLD are especially deficient in this dimension of language. This shortcoming touches upon many aspects of their communicative behavior. Inappropriate discourse, discourse that is lacking in content and organization, minimal speech prosody, and an insensitivity to context are evident in children with NLD.

For further information regarding the speech and language characteristics of children who exhibit the NLD phenotype, the reader may wish to consult Brookshire et al. (1995) and Fletcher, Dennis, and Northrup (1999).

Finally, it is clear that at least one verbal learning strategy of adolescents with NLD is distinct from, and inferior to, that adopted by normally developing adolescents and those with Basic Phonological Processing Disabilities (BPPD). Adolescents with NLD adopt a serially driven (essentially, rote) strategy rather than the semantically driven (language content) strategy employed by normally developing adolescents and those with BPPD when learning verbal material (Fisher & DeLuca, 1997). This difference in strategy usage persists from adolescence into adulthood.


References

Bloom, L. (1988). What is language? In M. Lahey (Ed.), Language disorders and language development (pp. 1-19). New York: MacMillan.

Boone, D. R., & Plante, E. (1993). Human communication and its disorders. (2nd ed.). Englewood Cliffs: Prentice Hall.

Brookshire, B. L., Fletcher, J. M., Bohan, T. P., Landry, S. H., Davidson, K. C., & Francis, D. J. (1995). Specific language deficiencies in children with early onset hydrocephalus. Child Neuropsychology, 1, 106-117.

Fisher, N. J., & DeLuca, J. W. (1997). Verbal learning strategies of adolescents and adults with the syndrome of Nonverbal Learning Disabilities. Child Neuropsychology, 3,192-198.

Fletcher, J. M., Dennis, M., & Northrup, H. (1999). Hydrocephalus. In K. O. Yeates, R. D. Ris, & H. G. Taylor (1999). Pediatric neuropsychology: Research, theory, and practice (pp. 25-46). New York: Guilford Press.

Humphries, T., Oram Cardy, J., Worling, D. E., & Peets, K. (2004). Narrativecomprehension and retelling abilities of children with nonverbal learningdisabilities. Brain and Cognition, 56, 77-88.

Kujala, T. et al. (2005). Neurophysiological evidence for cortical discrimination impairment of prosody in Asperger syndrome. Neuroscience Letters, 383, 260-265.

Richman, L. C., & Wood, K. M. (2002). Learning disability subtypes: Classification of high functioning hyperlexia. Brain and Language, 82(1), 10-21.

Rourke, B. P., & Tsatsanis, K. D. (1996). Syndrome of nonverbal learning disabilities: Psycholinguistic assets and deficits. Topics in Language Disorders, 16, 30-44.

Rourke, B. P., van der Vlugt, H., & Rourke, S. B. (2002). Practice of child-clinical neuropsychology: An introduction. Lisse, The Netherlands: Swets & Zeitlinger.



Addendum

Inspite of the above, many researchers and others continue to maintain that the verbal/linguistic skills of persons with NLD are intact or even above-average. Some point to the significant proportion of persons classified with NLD who exhibit a relatively normal or even superior Wechsler Verbal IQ as compared to Performance IQ as a reason for suggesting that their verbal/linguistic skills are well-developed. Failure to distinguish between simple (rote memory) and complex (conceptual) verbal skills and to consider the distinctions between and among the form, content, and function/pragmatics dimensions of language seem responsible for this. The notion that the language of persons with NLD is “(very) good,” pure and simple, is thus reinforced and the misconception that persons with NLD are “(very) bright” is promoted. Such is not the case (Question #19). It is also commonly inferred that these supposedly normal to superior verbal/linguistic skills will stand them in good stead for benefiting from “insight-oriented, dynamic psychotherapy.” In this instance as well, nothing could be further from the truth (Question #23).

On a related note, the use of a Verbal IQ-Performance IQ discrepancy of significant proportions as the principal criterion for the determination of NLD is clearly inappropriate (Question #10 and #11).


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