Two of the oldest and most widely used measures of intelligence are the Wechsler Scales of Intelligence and the Stanford-Binet Intelligence Scales. The following compares and contrasts recent versions of these two scales. Major ethical, legal, and sociocultural issues are explained.
Wechsler and Binet both believed that intelligence involved multiple types of mental abilities (Cherry, 2011). The original Stanford-Binet intelligence test provided one intelligence quotient (IQ) and this score was originally calculated by dividing the mental age by the chronological age of the test taker and multiplying this number by 100. Today, the scale is modified and a quantitative analysis of the subcomponents of the scale are calculated (Gregory, 2011). The SB5 (Stanford-Binet Intelligence Scales: fifth Edition) was developed based on the principle that five factors of intelligence fall in two domains, the nonverbal and the verbal. These five factors were derived from research and cognitive theories. Similarly, the original Wechsler scales had verbal and nonverbal domains (Gregory, 2011). Wechsler went beyond the limitations of the original Stanford-Binet with the development of the Wechsler Adult Intelligence Scale (WAIS), the Wechsler Intelligence Scale for Children (WISC), and the Wechsler Preschool and Primary Scale of Intelligence (WPPSI). The WAIS-III was a revised version of the WAIS with 14 subtests on two scales that provided a composite, verbal, and performance IQ score. The WAIS-IV is a revised version of the WAIS-III. With this new version, most items were included but two new subtests were added. A simplified test structure and a new emphasis on index scores allows for an understanding of cognitive functions (Gregory, 2011). With the new test, instead of a verbal and nonverbal breakdown in IQ, a fourfold breakdown is used. Thus, the new test provides an IQ score and four index scores. There are
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