diversity have perplexed efforts to design a classification system with which all will be pleased.
As noted earlier in this chapter, the most recent AAMR definition ( Luckasson, 1992) represents a significant departure from previous AAMR definitions. As such, it will be interesting to follow the next years to see whether AAMR continues to exert leadership in terms of state education codes and other agencies following the general framework of AAMR. The recently published DSM-IV ( APA, 1994) retained the IQ guidelines used in DSM-III-R; however, it did incorporate the 10 adaptive skill areas specified in Luckasson et al. ( 1992). Contrary to the AAMR scheme, DSM-IV retained the levels of retardation, and did not follow AAMR in employing levels of support. Currently, Division 33 of the American Psychological Association has a draft of yet another definition (see Jacobson & Mulick, 1993) providing the field with yet another definition of mental retardation from which to select. Agencies charged to serve persons with mental retardation will be free to cite any number of authorities for their definition of mental retardation, including the American Psychiatric Association's DSM-IV, the AAMR 1992 definition, or that resulting from the effort of Division 33 of the American Psychological Association. With the multiplicity of definitions likely to be available as models for agency criteria for who gets served, the variation from state to state in terms of who qualifies for services is likely to increase. For the research community the use of system-identified samples is likely to result in even less ability to generalize from study to study. The accumulation of knowledge about mental retardation is likely to be seriously compromised unless specification of markers characterizing samples is somehow instituted. In past years those of us working in the field of mental retardation could look on our colleagues studying learning disabilities (LD) with a sense of pity: How do they know who they are studying with the varied definitions of LD? It would appear that in the near future we will have achieved parity with our colleagues in the LD field.
Preparation of this chapter was supported, in part, by grants HC023C20002, H023C80072, and H023C30103 from the U.S. Office of Education to the first author. Opinions expressed herein are those of the authors and should not be interpreted to have agency endorsement.
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