Cognitive development of severely and profoundly mentally retarded individuals.

Corman and Escalona's scales for Object Permanence and Spatial Relationships were readministered to 71 severely and profoundly mentally retarded individuals five years after the last previous administration of the scales. Gains in mean scores were small but statistically significant for both scales. In addition, significantly more subjects gained than lost on Spatial Relationships, though not on Object Permanence. These findings provide evidence that the cognitive development of at least some severely and profoundly retarded individuals continues into early adulthood, even in the absence of special programs designed to promote such development.