Because no single characteristic defines intelligence, there can be no adequate process-based definition of intelligence. In principle, a combination of many empirically derived measures into a single index, as in a Binet test, would be appropriate. In practice, many of the relevant characteristics are simply impossible to measure. (Author/RD)

A directed forgetting task was used in an investigation of the conditions under which normal and educable mentally retarded junior high school students would disregard irrelevant information. Results showed that irrelevant information in memory interfered with the performance of only the retarded group, when given a minimal explanation of the…