Wechsler Intelligence Scales
A widely used series of intelligence tests developed by clinical psychologist David Wechsler.
The Wechsler Intelligence Scales are divided into two sections: verbal and nonverbal (or "performance"), with separate scores for each. Verbal intelligence, the component most often associated with academic success, implies the ability to think in abstract terms using either
words or mathematical symbols. Performance intelligence suggests the ability to perceive relationships and fit separate parts together logically into a whole. The inclusion of the performance section in the Wechsler scales is especially helpful in assessing the cognitive ability of children with speech and language disorders or whose first language is not English. The test can be of particular value to school psychologists screening for specific learning disabilities because of the number of specific subtests that make up each section.
The Wechsler Preschool and Primary Scales of Intelligence (WPPSI) have traditionally been geared toward children ages four to six, although the 1989 version of the test (WPPSI-III, 1989) extends the age range down to three years and upward to seven years, three months. The Verbal section covers the following areas: general information (food, money, the body, etc.); vocabulary (definitions of increasing difficulty); comprehension (responses to questions); arithmetic (adding, subtracting, counting); sentences (repeating progressively longer sentences); and similarities (responding to questions such as "How are a pen and pencil alike?"). The Performance section includes picture completion; copying geometric designs; using blocks to reproduce designs; working through a maze; and building an "animal house" from a model.
The Wechsler Intelligence Scale for Children (WISC), now in its second revision (WISC-III, 1991), is designed for children and adolescents ages six to sixteen. The WISC differs from the WIPPSI in the following notable ways: geometric designs are replaced by assembly of three-dimensional objects; children arrange groups of pictures to tell simple stories; they are asked to remember and repeat lists of digits; a coding exercise is performed in place of the animal house; and mazes are a subtest. For all of the Wechsler scales (which also include the Wechsler Adult Intelligence Scale, or WAIS), separate verbal and performance scores, as well as a total score, are computed. These are then converted using a scale divided into categories (such as average and superior), and the final score is generally given as one of these categories rather than as a number or percentile ranking.