Questions and Answers
Question # 1
You refer to NLD as a subtype of learning disabilities (LD).
How do you define LD?
The following are our general and specific working definitions of LD. These definitions arise from the part of our research program that has focussed on the delineation of reliable and valid subtypes of LD. For reviews of this work, see the following: Rourke, 1985, 1989b, 1991, 1995b, 2000a; Rourke and Conway, 1997; Rourke and Fuerst, 1991.
Learning Disabilities (LD) are specific patterns (subtypes) of neuropsychological assets and deficits that eventuate in specific patterns of formal (e.g., academic) and informal (e.g., social) learning assets and deficits. LD may also lead to specific patterns of psychosocial functioning. It is clear that these generalizations need to be construed and evaluated within the context of particular historical and sociocultural contexts.
Of particular interest to us are two subtypes of LD that we have identified in a reliable and valid manner: Nonverbal Learning Disabilities (NLD) and Basic Phonological Processing Disabilities (BPPD).
The NLD subtype (syndrome) is a specific pattern of neuropsychological assets and deficits that eventuates in the following: a specific pattern of relative assets and deficits in academic (well developed single-word reading and spelling relative to mechanical arithmetic) and social (e.g., more efficient use of verbal than nonverbal information in social situations) learning; specific, developmentally dependent patterns of psychosocial functioning. Typically, in children below the age of four years, psychosocial functioning is relatively normal or reflective of mild deficits. Following this period, emerging manifestations of externalized psychopathology are frequent; the child may be characterized as "hyperactive" and "inattentive" during this period. The usual course with respect to activity level is one of perceived "hyperactivity" through evident normoactivity to hypoactivity with advancing years. By older childhood and early adolescence, the typical pattern of psychopathology in evidence is of the internalized variety, characterized by withdrawal, anxiety, depression, atypical behaviors, and social skill deficits.
The BPPD subtype is a specific pattern of neuropsychological assets and deficits that eventuates in the following: a specific pattern of relative assets and deficits in academic (poorly developed single-word reading and spelling relative to mechanical arithmetic) and social (e.g., more efficient use of nonverbal than verbal information in social situations) learning. The neuropsychological profile and outcomes of this subtype of LD stand in marked contrast to NLD. In particular, the BPPD subtype does not lead in a necessary manner to any particular configuration of difficulties in psychosocial/adaptive behavior.
For a more extensive description of NLD and BPPD, the interested reader is referred to Rourke et al. (2002).