Memory-for-Designs, intelligence, and achievement of educable mentally retarded children

Relationships between Memory-for-Designs test, Wechsler Intelligence Scale for Children (WISC), and Wide Range Achievement Test (WRAT) were determined for classes of 12 and 14 educable mentally retarded children. Rank-difference rs showed that Memory-for-Designs errors correlated significantly with WISC Verbal IQs (-0.78), WISC Performance IQs (-0.85), and WISC Full Scale IQs (-0.96) for Class 1, and with WRAT Reading (-0.79) and WRAT Arithmetic (-0.70) for Class 2, implying that Memory-for-Designs may supplement the other tests in placement of children into educable mentally retarded classes. The high r (-0.96) between Memory-for-Designs and WISC Full Scale IQs indicates that a major component in intelligence is visual memory, which accounts for 84% of the variance of intelligence and suggests the possibility of improving intelligence through visual memory training in the schools.