Performances of 18 retarded young adults on the Porteus Maze Test (a measure of planning capacity and foresight) were compared with those of 117 first- through fourth-grade nonretarded children. (Author)

The performance of 4 groups of mentally retarded Ss, ages 14-17 with mental ages of 8-11, was compared to that of 90 non retarded Ss, grades K-5 with comparable mental ages, on the solution of 2 and 3 disc Hanoi Tower puzzles, solutions to which require logical forsight. (BB)

Intelligence levels of a sample of 180 Down's syndrome children were reported, and the results indicated that their abilities are not as limited as previously thought. (Author)

The effects of differences in the definition of mental retardation on prevalence were demonstrated with hypothetical data. (Author)

The hypothesis that it is possible to find among a normal population a group with the same level of intelligence as a group of institutionalized retarded persons was confirmed in a study of 2,000 19-year-old males registering for military service. (Authors)

The alpha rhythm frequencies (8 to 13 cycles per second, occurring during a S's relaxed state with eyes closed, measured by the electroencephalogram) of three groups of Ss (30 Down's Syndrome residents, 21 psychiatric patients, and 10 university students) aged 13 to 24 years, were determined according to explicit criteria. (Author/MC)

In the article, Robert Lehrke responds to the criticism of the authors who criticized his paper, A Theory of X-Linkage of Major Intellectual Traits,'' appearing in the same journal. (CB)