The test comprises ten core subtests and five supplemental ones. The supplemental subtests are used to accommodate children in certain rare cases, or to make up for spoiled results which may occur from interruptions or other circumstances. Testers are allowed no more than two substitutions in any FSIQ test, or no more than one per index. These subtests then generate a Full Scale score (FSIQ,) and four composite scores known as indices: Verbal Comprehension (VCI,) Perceptual Reasoning (PRI,) Processing Speed (PSI) and Working Memory (WMI.)
The WISC is one of a family of Wechsler intelligence scales. Subjects over 16 are tested with the Wechsler Adult Intelligence Scale (WAIS), and children ages three to seven years, three months are tested with the Wechsler Preschool and Primary Scale of Intelligence (WPPSI).
Each of the ten core subtests is given equal weighting towards full-scale IQ. There are three subtests for both VCI and PRI, thus they are given 30% weighting each; in addition, PSI and WMI are given weighting for their two subtests each.
The VCI's subtests are as follows:
* Vocabulary - straightforward questions over the meaning of words
* Similarities - asking how two concepts are alike
* Comprehension - questions about social situations or common concepts
* Information (supplemental) - general knowledge questions
* Word Reasoning (supplemental) - children are presented with one to three riddle-style clues and asked to determine what the tester is describing.
The PRI's subtests are as follows:
* Block Design - children put together red-and-white blocks in a pattern according to a displayed model. This is timed, and some of the more difficult puzzles award bonuses for speed.
* Picture Concepts - children are shown rows of pictures, and are asked to find a common bond with one picture in each row.
* Matrix Reasoning - children are shown an array of pictures with one missing square, and select the picture that fits the array from five options.
* Picture Completion (supplemental) - children are shown artwork of common objects with a missing part, and asked to identify the missing part by pointing and/or naming.
The WMI's subtests are as follows:
* Digit Span - children are orally given sequences of numbers and asked to repeat them, either as heard or in reverse order.
* Letter-Number Sequencing - children are orally given sequences of letters and numbers together, and asked to repeat them in both numerical order and alphabetical order.
* Arithmetic (supplemental) - orally administered arithmetic questions. Timed.
The PSI's subtests are as follows:
* Coding - children under 8 mark rows of shapes with different lines according to a code, children over 8 transcribe a digit-symbol code. Time-limited with bonuses for speed.
* Symbol Search - children are given rows of symbols and target symbols, and asked to mark whether or not the target symbols appear in each row.
* Cancellation (supplemental) - students are to mark lines through objects that do not belong in a page of randomly-arranged objects and one of orthogonally-arranged objects.