Wechsler Preschool and Primary Scale of Intelligence–Third Edition

The Wechsler Preschool and Primary Scale of Intelligence–Third Edition (WPPSI-III), described in this entry, is designed to measure the general cognitive ability of young children from 2 years 6 months (2–6) to 7 years 3 months (7–3). The WPPSI-III measures verbal skills, including knowledge of words and general information, reasoning using pictorial cues, and solving problems with blocks and puzzles. The WPPSI-III also measures general language ability including receptive and expressive vocabulary.

The original Wechsler Preschool and Primary Scale of Intelligence (WPPSI) was published in 1967 in response to the development of educational programs for young children such as Head Start. These programs raised awareness of the need for accurate assessment of young children and evaluation of the effectiveness of early childhood education. The WPPSI was essentially a downward extension of the Wechsler Intelligence Scale for Children (WISC), first published in 1949. The WPPSI was revised in 1989, and the current edition was published in 2002, representing improvement of the scale to reflect input from examiners as well as research into the nature of intelligence in young children.

The WPPSI-III has been updated to measure aspects of intelligence based on Cattell-Horn-Carroll theory. Three new subtests measure fluid reasoning, which is the ability to solve problems using unfamiliar tasks or stimulus materials. Two new subtests measure processing speed, which requires timed responses on tasks requiring eye-hand coordination, and two new subtests measure expressive and receptive vocabulary.

The WPPSI-III covers two broad age groups, 2–6 to 3–11 and 4–0 to 7–3. The WPPSI-III overlaps with the Wechsler Intelligence Scale for Children – Fourth Edition (WISC-IV) at ages 6–0 to 7–3. The choice of which test to use depends on the child's estimated cognitive functioning and whether the child has previously been exposed to either test.

WPPSI-III subtests are designated as either core, supplemental, or optional. Core subtests are those that combine to form the Verbal, Performance, and Full Scale IQ scores. Supplemental subtests may be used to replace core subtests or to provide additional information. Optional subtests provide additional information but may not be used as replacements for core subtests.

At the younger age range, from 2–6 to 3–11, four core subtests are available. Receptive Vocabulary and Information form the Verbal scale. Block [Page 941]Design and Object Assembly form the Performance scale. The Verbal and Performance scores are combined to determine the Full Scale IQ score. A supplemental subtest, Picture Naming, can be used as a substitute for Receptive Vocabulary or can be combined with Receptive Vocabulary to form the General Language Composite.

At the older age range, from 4–0 to 7–3, Information, Vocabulary, and Word Reasoning form the Verbal scale. Block Design, Matrix Reasoning, and Picture Concepts constitute the Performance scale. The Verbal and Performance IQ scores are used to determine the Full Scale IQ score. There are two supplemental subtests for the Verbal scale, Comprehension and Similarities, and two supplemental subtests for the Performance scale, Picture Completion and Object Assembly. The supplemental subtests may be used as replacements for other subtests in the same scale. A third scale for this age group, Processing Speed, consists of one core subtest, Coding, and one supplemental subtest, Symbol Search. The General Language Quotient consists of two tests that are optional at this age range, Receptive Vocabulary and Picture Naming.

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