Wechsler Preschool and Primary Scale of Intelligence

The third edition of the Wechsler Preschool and Primary Scale of Intelligence (WPPSI-III; published by the Psychological Corporation, http://www.harcourtassessment.com) is an individually administered, norm-referenced clinical instrument for assessing the intelligence of children between the ages of 2 years 6 months (2:6) and 7 years 3 months (7:3). The scale provides subtest and composite scores that represent intellectual functioning in verbal and performance cognitive domains, as well as a composite score that represents a child's general intellectual ability.

The scale consists of 14 subtests, grouped into three general categories: core, supplemental, and optional. The age range has been divided into two age bands to accommodate the substantial changes in children's cognitive development between the ages 2:6 and 7:3. For children age 2:6 through 3 years 11 months (3:11), the core verbal subtests are Receptive Vocabulary and Information. For the Receptive Vocabulary subtest, children look at pictures and are instructed to “Show me the cup” and “Show me raining.” The core performance subtests are Block Design and Object Assembly. For Object Assembly, a child is presented with pieces of a puzzle and instructed to fit the pieces together in 90 seconds. Picture Naming is a supplemental verbal subtest. Four composite scores are possible for this age band: Verbal IQ, Performance IQ, Full Scale IQ, and General Language Composite.

For children age 4 years through 7:3, the core verbal subtests are Information, Vocabulary, and Word Reasoning. For the Information subtest, a child responds to a question such as “Show me your nose” and “How many days make a week?” The core performance subtests are Block Design, Matrix Reasoning, and Picture Concepts. For the Matrix Reasoning subtest, the child looks at an incomplete matrix of pictures and chooses the missing portion from 4 or 5 choices. Coding is the core Processing Speed subtest. The supplemental verbal subtests are Comprehension and Similarities, and supplemental performance subtests are Picture Completion and Object Assembly. Symbol Search is the supplemental processing-speed subtest. Receptive Vocabulary and Picture Naming are optional verbal subtests but cannot be substituted for core Verbal subtests. Five composites are possible for this age band: Verbal IQ, Performance IQ, Processing Speed Quotient, Full Scale IQ, and General Language Composite.

For children age 2:6 to 3:11, administration of the core subtests takes 30 to 35 minutes; if the supplemental subtest is administered as well, 5 to 7 minutes should be added to the testing time. For children age 4 years to 7:3, administration of the core subtests takes 40 to 50 minutes; if all subtests are administered, an additional 30 to 35 minutes will be required.

The WPPSI-III can be used to obtain a comprehensive assessment of general intellectual functioning. The scale can also be used as part of an assessment to identify intellectual giftedness, cognitive developmental delays, and mental retardation. In addition, the results can serve as a guide for placement decisions in clinical or school-related programs.