Wechsler Intelligence Scale for Children


The Wechsler Intelligence Scale for Children, developed by David Wechsler, is an individually administered intelligence test for children between the ages of 6 and 16. The Fifth Edition is the most recent version.
The WISC-V takes 45–65 minutes to administer. It generates a Full Scale IQ that represents a child's general intellectual ability. It also provides five primary index scores: Verbal Comprehension Index, Visual Spatial Index, Fluid Reasoning Index, Working Memory Index, and Processing Speed Index. These indices represent a child's abilities in discrete cognitive domains. Five ancillary composite scores can be derived from various combinations of primary or primary and secondary subtests.
Five complementary subtests yield three complementary composite scores to measure related cognitive abilities relevant to assessment and identification of specific learning disabilities, particularly dyslexia and dyscalculia. Variation in testing procedures and goals can reduce time of assessment to 15–20 minutes for the assessment of a single primary index, or increase testing time to three or more hours for a complete assessment, including all primary, ancillary, and complementary indices.

History

The original WISC was an adaption of several of the subtests that made up the Wechsler–Bellevue Intelligence Scale but also featured several subtests designed specifically for it. The subtests were organized into Verbal and Performance scales and provided scores for Verbal IQ, Performance IQ, and Full Scale IQ.
Each successive edition has re-normed the test to compensate for the Flynn effect, ensuring not only that the norms do not become outdated which is suggested to result in inflated scores on intelligence measures, but that they are representative of the current population. 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. A revised edition was published in 1974 as the WISC-R, featuring the same subtests. However, the age range was changed from 5–15 to 6–16.
The third edition was published in 1991 and brought with it a new subtest as a measure of processing speed. 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, the Perceptual Organization Index, the Freedom from Distractibility Index, and the Processing Speed Index.
The WISC-IV was produced in 2003. The WISC-V was published in 2014. The WISC-V has a total of 21 subtests. It yields 15 composite scores.

Test format

The WISC is one test in a suite of Wechsler intelligence scales. Subjects 16 and over are tested with the Wechsler Adult Intelligence Scale, and children ages two years and six months to seven years and seven months are tested with the Wechsler Preschool and Primary Scale of Intelligence. There is some overlap between tests: children aged 6 years 0 months through 7 years 7 months can complete the WPPSI or the WISC; children aged 16 can complete the WISC-V or the WAIS-IV. Different floor effect and ceiling effect can be achieved using the different tests, allowing for a greater understanding of the child's abilities or deficits. This means that a 16-year-old adolescent who has an intellectual disability may be tested using the WISC-V so that the clinician may see the floor of their knowledge.
There are five primary index scores, the Verbal Comprehension Index, Visual Spatial Index, Fluid Reasoning Index, Working Memory Index, and Processing Speed Index. Two subtests must be administered to obtain each of the primary index scores; thus, a total of 10 subtests are primary subtests. The Full Scale IQ is derived from 7 of the 10 primary subtests: Both Verbal Comprehension subtests, one Visual Spatial subtest, two Fluid Reasoning subtests, one Working Memory subtest, and one Processing Speed subtest. Verbal Comprehension and Fluid Reasoning are weighted more heavily in the Full Scale IQ to reflect the importance of crystallized and fluid abilities in modern intelligence models.
The VCI is derived from the Similarities and Vocabulary subtests. The Verbal Comprehension scale subtests are described below:
The VCI is an overall measure of verbal concept formation and is influenced by semantic knowledge.
The VSI is derived from the Block Design and Visual Puzzles subtests. These subtests are as follows:
The VSI is a measure of visual spatial processing.
The FRI is derived from the Matrix Reasoning and Figure Weights subtests. The Fluid Reasoning scale subtests are described below:
The FRI is a measure of inductive and quantitative reasoning.
The WMI is derived from the Digit Span and Picture Span subtests. The Working Memory scale's subtests are as follows:
The WMI is a measure of working memory ability.
The PSI is derived from the Coding and Symbol Search subtests. The Processing Speed subtests are as follows:
The PSI is a measure of processing speed.
The 2014 publication of the WISC-V contained five ancillary index scores that may be derived for special clinical purposes or situations: the Quantitative Reasoning Index, the Auditory Working Memory Index, the Nonverbal Index, the General Ability Index, and the Cognitive Proficiency Index. Three of these ancillary index scores can be derived from the 10 primary subtests. The QRI and the AWMI can each be derived by administering one additional subtest from subtests that are within one of the five primary scales but are not primary. The set of these subtests is termed secondary subtests.
Two ancillary index scores termed the were released the year after the 2014 publication, so are not included in the published manuals. These are the Verbal Index and the Expanded Fluid Index .
Three complementary index scores are available to measure cognitive processes that are important to achievement and are sensitive to specific learning disabilities. The complementary index scores are the Naming Speed Index, designed to measure rapid automatized naming, and the Symbol Translation Index, designed to measure visual-verbal associative memory, which is sometimes termed visual-verbal paired associate learning in the published literature. The Naming Speed scale contains Naming Speed Literacy, which measures rapid automatic naming, and Naming Speed Literacy, which is the only commercially published and normed measure of rapid quantity naming, also known as subitizing. Naming Speed Quantity is uniquely sensitive to math achievement and specific learning disabilities in mathematics.

Psychometric properties

The WISC–V normative sample consisted of 2,200 children between the ages of 6 and 16 years 11 months. In addition to the normative sample, a number of special group samples were collected, including the following: children identified as intellectually gifted, children with mild or moderate intellectual disability, children with specific learning disorders, children with ADHD, children with disruptive behavior, children who are English Language Learners, children with autism spectrum disorder with language impairment, children with autism spectrum disorder without language impairment, and children with traumatic brain injuries.
The WISC–V is also linked with measures of achievement, adaptive behavior, executive function, and behavior and emotion. Equivalency studies were also conducted within the Wechsler family of tests and with a Kaufman test enabling comparisons between various intellectual ability scores over the lifespan. A number of concurrent studies were conducted to examine the scale's reliability and validity. Evidence of the convergent and discriminant validity of the WISC–V is provided by correlational studies with the following instruments: WISC–IV, WPPSI–IV, WAIS–IV, WASI–II, KABC–II, KTEA–3, WIAT–III, NEPSY–II, Vineland–II, and BASC–II. Evidence of construct validity was provided through a series of factor-analytic studies and mean comparisons using matched samples of special group and nonclinical children.

Uses

The WISC is used not only as an intelligence test, but as a clinical tool. Some practitioners use the WISC as part of an assessment to diagnose attention-deficit hyperactivity disorder and learning disabilities, for example. This is usually done through a process called pattern analysis, in which the various subtests' scores are compared to one another and clusters of unusually low scores in relation to the others are searched for. David Wechsler himself suggested this in 1958.
However, the research does not show this to be an effective way to diagnose ADHD or learning disabilities. The vast majority of children with ADHD do not display certain subtests substantially below others, and many children who display such patterns do not have ADHD. Other patterns for children with learning disabilities show a similar lack of usefulness of the WISC as a diagnostic tool. Although, when Cattell Horn Carrol theory is used to interpret the WISC–V subtests, things tend to make a great deal more sense.
When diagnosing children, best practice suggests that a multi-test battery should be used as learning problems, attention, and emotional difficulties can have similar symptoms, co-occur, or reciprocally influence each other. For example, children with learning difficulties can become emotionally distraught and thus have concentration difficulties, begin to exhibit behavior problems, or both. Children with ADD or ADHD may show learning difficulties because of their attentional problems or also have learning disorder or disability. In short, while diagnosis of any childhood or adult difficulty should never be made based on IQ alone the cognitive ability test can help rule out, in conjunction with other tests and sources of information, other explanations for problems, uncover co-morbid problems, and be a rich source of information when properly analyzed and care is taken to avoid relying simply on the single summary IQ score.
The WISC can be used to show discrepancies between a child's intelligence and his/her performance at school. In a clinical setting, learning disabilities can be diagnosed through a comparison of intelligence scores and scores on an achievement test, such as the Woodcock Johnson III or Wechsler Individual Achievement Test II. If a child's achievement is below what would be expected given their level of intellectual functioning, then a learning disability may be present. Other psychologists and researchers believe that the WISC can be used to understand the complexities of the human mind by examining each subtest and can, indeed, help in diagnosing learning disabilities.
Subsequently, the WISC can be used as part of an assessment battery to identify intellectual giftedness, learning difficulties, and cognitive strengths and weaknesses. When combined with other measures such as the Adaptive Behavior Assessment System–II and the Children's Memory Scale its clinical utility can be enhanced. Combinations such as these provide information on cognitive and adaptive functioning, both of which are required for the proper diagnosis of learning difficulties and learning and memory functioning resulting in a richer picture of a child's cognitive functioning.
The WISC–V is linked with the Kaufman Test of Educational Achievement–Third Edition and the Wechsler Individual Achievement Test-III, a measure of academic achievement. This linkage provides information on both cognitive ability and academic achievement in children. Tests of intellectual functioning are used extensively in school settings to evaluate specific cognitive deficits that may contribute to low academic achievement, and to predict future academic achievement. Using the WISC–V in such a manner provides information for educational intervention purposes, such as interventions that address learning difficulties and cognitive deficits.
The WISC–V can also be used to assess a child's cognitive development, with respect to the child's chronological age. Using such comparisons with other sources of data, the WISC can contribute information concerning a child's developmental and psychological well-being. Very high or very low scores may suggest contributing factors for adjustment difficulties in social contexts that present problems in accepting such developmental diversity.

Translations

WISC has been translated or adapted to many languages, and norms have been established for a number of countries, including Spanish, Portuguese, Arabic, Icelandic, Norwegian, Swedish, Finnish, Czech, Croatian, French, German, English, Welsh, Dutch, Japanese, Chinese, Korean, Greek, Romanian, Indonesian, Slovenian and Italian. Separate norms are established with each translation.. India uses the Malin's Intelligence Scale for Indian Children, an adaptation of WISC by Arthur J. Malin. However, the norms of MISIC are outdated and many Clinical Psychologists do not use this test in their practice due to possible errors in measured IQs because of Flynn effect. Being from a developing nation, Indian children have undergone numerous changes in their intellectual abilities in last 5 decades, which makes the application of MISIC redundant, though some psychometricians suggest that such changes are minor, hence the test is still applicable. Instead of MISIC, the fourth edition of WISC that was adapted and standardized for India in 2012, is more commonly accepted and used by clinicians. Being the most widely used test for intelligence assessment in India, MISIC still has its supporters, and will continue to be used by clinicians all over the country, owing to which its norms must be updated. The Japanese version of the WISC-IV was developed by Japanese psychologists Kazuhiko Ueno, Kazuhiro Fujita, Hisao Maekawa, Toshinori Ishikuma, Hitoshi Dairoku, and Osamu Matsuda.

Literature