Historical Analysis of the Concept of Intellectual Disability : The emergence of Heber definition of mental retardation in American scene

American Association on Mental Deficiency which is the oldest and most influential organization in the field of intellectual and developmental disabilities issued official manuals of mental retardation in 1959 and 1961. These manuals showed the epoch-making definition of mental retardation which had dominated subsequent years through 2001 when AAMD changed the name of mental retardation for intellectual disability. That means that the latter half of 20th century could be called as the century of mental retardation. In this article we analyzed the emergence of 1961 definition of mental retardation and its features from socio-historical perspective. Just after AAMD published the manual describing its definition in 1961, mental retardation became the name of intellectual disability for the first time. Mental retardation was first configured as a present condition instead of pathological phenomena in 1961 definition. Intellectual disability was first defined inclusively as the concept that has three key elements. They are (a) attenuated general intellectual functioning, (b) subnormal level in adaption behavior which refers to a person' s ability to live independently, to hold a job, and to conform to the social standards of the community, (c) developmental period. It was not until 1961 that AAMD adopted three components definition in the name of mental retardation. According to 1961 manual of mental retardation, attenuated intellectual functioning is confirmed by individual IQ test and adaptive behavior was said to include the ideas of "maturation" , "learning" and "social adjustment" , however, didn' t have any appropriate measurement scale. The 1961 definition has positive features mentioned above, however, they have controversial problems. One of them is the cut-off point of IQ. They provided a rather high IQ limit (i.e., close to 85). As the result of this definition, many slow learners including ethical minority children were placed in segregated classrooms as mild retarded students. This caused the debate whether special classes for the mildly handicapped were justifiable. Another controversial problem was an etiological category of ‘cultural-familial retardation' which explained as the largest subgroup of the mentally retarded persons. This group had become the object of the heated dispute. That is because the adjective term ‘familial' implies inheritance and the adjective term ‘cultural' implies ‘environment' . These conflicting terms were made up into ‘cultural–familial mentally retarded' . The two group approach emerged from this heated dispute