The child with a reading disability typically is of average or superior intelligence, able to achieve an I. Q. of 90 to 150 (or more) on oral intelligence tests such as the Stanford-Binet, although rating considerably lower on group tests of intelligence which require reading the questions or instructions. Such a child's failures in school are due not to lack of intelligence but to inability to read well; for example, competency in arithmetic computation is rarely affected, since learning to add, subtract, multiply, divide, etc., is not dependent upon ability to read to the same extent that learning many other subjects is dependent on it. Difficulties in writing and spelling words often are associated with reading disabilities, but disabilities for reading and spelling may appear independently of one another.

Reading disabilities are far more common among boys than girls: statistical studies indicate that eighty per cent or more of children with disabilities in reading are boys. We do not yet have an adequate explanation for this.1