| The present study consolidated the two opposing views of the developmental versus difference controversy in mental retardation by providing evidence for both developmental similarities and differences in the cognitive functioning of retarded and nonretarded persons matched for mental age. By conceptualizing cognition as two hierarchical processes (Jensen, 1968), it proposed that on Level I indices of cognitive functioning retarded and nonretarded groups would demonstrate developmental similarities whereas on Level II measures, differences in cognitive performance would occur. Results were expected despite noncognitive factors of organicity and institutionalization.; This study also proposed that mental age scores of retarded and nonretarded persons, although numerically similar, would be qualitatively different with more Level II items occurring in scores of nonretarded groups and more Level I items occurring in mental age scores of retarded groups. Finally, this study examined the relationship of social age measures to cognitive performance.; To test these propositions eighty retarded subjects with IQ's between 50 and 70 were compared to thirty nonretarded subjects with IQ's in the normal range. All subjects were matched on mental age and the effects of organicity and institutionalization were controlled by comparing retarded subjects on these factors. Motivation was equalized for all subjects by providing both intrinsic and extrinsic rewards.; Subjects were tested using the Stanford-Binet Intelligence Scale (L-M), the Vineland Social Maturity Scale, and three tests of concept formation, the Object Sorting test parts I and II, and the Picture Pairing Test.; Results indicated that retarded and nonretarded persons performed in a similar manner on Level I measures and in a different manner on Level II measures, as predicted. These results existed independently of sex, race, SES, organicity and institutionalization. In addition, the mental age scores of retarded and nonretarded persons were found to be composed of different skills. More Level I items comprised the mental age scores of retarded subjects while more Level II items comprised the mental age score of nonretarded subjects. Social age scores were not related to cognitive performance.; A lack of organizational ability in mental retardation (Spitz, 1962) was used to explain these findings. Research examining the effects of training on the abstract skills of the retarded was suggested. |
