Mental retardation is defined not only in terms of characteristics but also of cause: "Mentally retarded children have suffered from a severe brain disease while in the uterus or in early childhood and this has disturbed the normal development of the brain and produced serious anomalies in mental development ... its consequence is an anomalous development of brain function. The mentally retarded child is sharply distinguished from the normal by the range of ideas he can comprehend and by the character of his perception of reality." Ziegler E. F. (1992, p. 5, 10). Thus, mental retardation is dependent upon the occurrence, or suspected occurrence, of brain injury. It also might be noted that this concept of mental retardation is not independent of socio-political implications. Ziegler described the approach to retardation in such countries as the United States and England in the following words:
In order to separate this group of children (mentally retarded) in the Capitalist countries, all children between 10 and 11 years of age undergo short psychological tests—tests of intellectual ability. These consist of a series of tests requiring shrewdness and general knowledge. Those children who do well in these tests are placed in class "A" where pupils pursue an advanced programme and later transfer to an advanced type of school. The second group, placed in the middle by the test, are put in class "B" and the third group which has the lowest marks, are treated as having inferior ability and put in class "C."
Pupils in this last group are considered incapable of receiving a complete education; they are sent to a lower type of school and when they are finished they cannot progress further and have to remain unqualified workers. It is quite clear that such a system of selecting children—as though they were of "low intellectual level"—openly carries a social class bias.......
