A study of the similar structure hypothesis in mentally-retarded adults and nonretarded children of comparable mental age

Alan Philip Hore, Fordham University


Research on the cognitive functioning of mentally retarded persons has crystallized into three positions. The developmental position holds that retarded and nonretarded subjects, when matched for mental age, will not vary in the way they think. The conventional difference position states that the performance of retarded subjects will be inferior, because of neurological deficits associated with mental retardation. The unconventional difference asserts that the retarded subjects will do better, because longer experience of life enhances cognitive development. Research has shown support for each position. This study attempted a further test using a neglected group, mentally retarded adults. It also attempted a stringent study that controlled for variables that may influence the testing of mentally retarded subjects, and performance on Piagetian tasks, namely, organicity, institutionalization, expectancy of failure, effects of reinforcement, outerdirectedness, comprehension of verbal instructions, socioeconomic status, race, sex, and education. Forty retarded adults aged 20 to 29, six aged 40 to 49, and 40 nonretarded children of comparable mental age (between 7 years 5 months, and 9 years 5 months) were given a series of Piagetian tasks, covering classification, transitivity and conservation. The older retarded group had to be excluded from formal analysis, as sufficient numbers of subjects cold not be located. A comparison between the retarded (20-29) group and the nonretarded group yielded mixed results. On four of the seven tasks (Class Inclusion, Transitivity of Length, Conservation of Length, and Conservation of Weight), the difference between the means was not significant, thereby giving support to the developmental position. On the remaining three tasks (Some-All, Transitivity of Weight, and Conservation of Area) the nonretarded group did significantly better than the retarded group, thus supporting the difference position. No support was found for the unconventional difference position. An evaluation of the shortcomings of the specific Piagetian tasks used indicated that the overall results on the classification and transitivity tasks probably favored the difference position. The poor response to the conservation tasks raised a caveat about using the performance on those tasks to support either position. Other aspects of the testing were discussed. Some corollaries affecting the cognitive functioning of mentally retarded adults emerged as particularly important.

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Recommended Citation

Hore, Alan Philip, "A study of the similar structure hypothesis in mentally-retarded adults and nonretarded children of comparable mental age" (1988). ETD Collection for Fordham University. AAI8809472.