Throughout the past several decades, educators and researchers have debated the concept of mental retardation (Clausen, 1967; Zigler, 1967), particularly regarding its etiology, prevalence, and viability as a discrete and reliable diagnostic category. At the heart of the debate is the fact that mild mental retardation (MMR), as a diagnostic category, subsumes cases with biological and psychosocial etiologic patterns. Some researchers have termed the latter etiology "mental retardation of unknown origins."
Recently, this debate has intensified because of the decision by the American Association on Mental Retardation (AAMR) to abolish the levels of mental retardation based on cognitive dysfunction (Mild, Moderate, Severe, and Profound). Instead, AAMR now differentiates cases of mental retardation based on needed levels of supports across four domains. In fact, the new definition (Luckasson, 1992) obscures the implicit distinctions between subgroups regarding their etiology - given that (a) most cases of mild mental retardation are of unknown etiology while a much larger percentage of cases of more severe retardation have "known etiologies," and (b) people with mild mental retardation do not experience the same impairments and problems characterizing people with more severe forms of mental retardation.
DEFINITIONS OF MILD
What constitutes MMR? Is it qualitatively different from other more severe forms of mental retardation as differences in etiology and behavior may suggest, or is it to be conceptualized on the continuum of cognitive impairment? Current practices attempt to group people with MMR under a single rubric with other people with more severe forms of mental retardation, which we believe belies the fact that these two groups of people are distinctively different. At the same time, it is important to consider how MMR differs qualitatively and quantitatively from children identified as learning disabled (LD). We contend that MMR needs to be reconceptualized as a diagnostic category.
Our primary thesis is that MMR differs markedly from other cases of mental retardation and, as such, must he recognized separately from moderate, severe, and profound forms and not as a subgroup of people with mental retardation. In the past, educators have argued that the classification system used for "diagnosis" should reflect this difference - through use of such terms as educable mental retardation. If we are to recognize the unique characteristics and needs of this group, we should explore a categorization apart from mental retardation. We need a new term that captures the pervasive weakness in abstract reasoning and problem-solving that some children exhibit, rather than the "general dysfunction" evident across contexts in moderate to profound forms.
To support our contention for the need to differentiate the group now called "mildly mentally retarded" from other levels of mental retardation (i.e., moderate, severe, and profound mental retardation), we demonstrate that MMR can be understood only in terms of the transaction between the child's cognitive inefficiencies and the environmental demands for problem-solving. The "condition" is highly contextual and is relative to the environment. The confusion apparent over the relativity or contextual nature of MMR is not found for other levels of mental retardation. Further, this confusion is reflected in the extreme variability in prevalence rates for MMR, whereas highly stable prevalence rates are reported for cases of mental retardation with IQs below 50. Last, some recent evidence suggests that it is becoming increasingly difficult to differentiate the upper levels of MMR from certain general forms of LD; and, in practice, it appears that a substantial segment of children currently classified as LD would more accurately be classified as MMR, particularly in urban schools (Gottlieb, Alter, Gottlieb, & Wishner, 1994). Before developing our case for the uniqueness of MMR, we examine why present policies and program funding rely on categorizations of MMR to ensure services for all students with mental retardation. …