These scores are intended to provide more detailed information on cognitive abilities that contribute to performance on the subtest. The WISC-IV also produces seven process scores on three subtests: block design, cancellation and digit span. 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 WISC-IV generates a Full Scale IQ (FSIQ) which represents overall cognitive ability, the four other composite scores are Verbal Comprehension index (VCI), Perceptual Reasoning Index (PRI), Processing Speed Index (PSI) and Working Memory Index (WMI).Įach of the ten core subtests is given equal weighting towards full scale IQ. A total of five composite scores can be derived with the WISC–IV. Testers are allowed no more than two substitutions in any FSIQ test, or no more than one per index. 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. The five new subtests include three core tests: Picture Concepts, Letter-Number Sequencing, Matrix Reasoning and two supplemental tests: Cancellation and Word Reasoning. The WISC-IV is divided into fifteen subtests, ten of which formed part of the previous WISC III. This means that a 16 year old child who has mental retardation may be tested using the WISC-IV so that the clinician may see the floor of their knowledge (the lowest level). Different floor and ceiling effects can be achieved using the different tests, allowing for a greater understanding of the child’s abilities or deficits. There is some overlap between tests, with children aged 7 being able to complete the WPPSI or the WISC-IV, and children aged 16 being able to complete the WISC-IV or the WAIS. Subjects 16 and over 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). The WISC is one of a family of Wechsler intelligence scales. Additional updates and refinements include changes to the questions to make them less biased against minorities and females, and updated materials to make them more useful in the administration of the test. Ensuring not only that the norms do not become outdated which is suggested to result in inflated scores on intelligence measures, but that they are representative of the current population (Flynn, 1984, 1987, 1999 Matarazzo, 1972). Each successive version has re-normed the test to compensate for the Flynn effect. The current version, the WISC-IV, was produced in 2003 followed by the UK version in 2004. In addition to the traditional VIQ, PIQ, and FSIQ scores, four new index scores were introduced to represent more narrow domains of cognitive function: the Verbal Comprehension Index (VCI), the Perceptual Organization Index (POI), the Freedom from Distractibility Index (FDI), and the Processing Speed Index (PSI). The third edition was published in 1991 (WISC-III Wechsler, 1991) and brought with it a new subtest as a measure of processing speed. A revised edition was published in 1974 as the WISC-R (Wechsler, 1974), featuring the same subtests however the age range was changed from 5-15 to 6-16. The subtests were organized into Verbal and Performance scales, and provided scores for Verbal IQ (VIQ), Performance IQ (PIQ), and Full Scale IQ (FSIQ). The original WISC (Wechsler, 1949) was an adaption of several of the subtests which made up the Wechsler–Bellevue Intelligence Scale (Wechsler, 1939) but also featured several subtests designed specifically for it. The WISC takes 65-80 minutes to administer and generates an IQ score which represents a child’s general cognitive ability. David Wechsler, is an individually administered intelligence test for children between the ages of 6 and 16 inclusive that can be completed without reading or writing. The Wechsler Intelligence Scale for Children (WISC), developed by Dr.
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