Comparison of two sets of Piagetian scales with severely and profoundly retarded children.

Corman and Excalona's (1969) scales for Object Permanence and Spatial Relationships and the corresponding scales of Uzgiris and Hunt (1975) were administered to 64 severely and prfoundly retarded children. Most of the findings applied equally to both sets of scales: the scoring reliability was very high; the total scores did not vary as a function of subject characteristics (except IQ) or testing conditions; differences in the difficulty of the items did not correspond closely to those reported for nonretarded infants, and the scalability of the items was much lower. Less time was required to administer the two scales constructed by Uzgiris and Hunt, but their Object Permanence scale showed a pronounced ceiling effect and the internal consistency of their Spatial Relationships scale was unacceptably low.