The Wechsler

Intelligence Scales

By Jill Hutzel and K.W.

Overview

• The Wechsler intelligence scales were developed by Dr. David Wechsler, a clinical psychologist at Bellevue Hospital. His initial test, the Wechsler-Bellevue Intelligence Scale, was published in 1939 and was designed to measure intellectual performance by adults. Wechsler constructed the WBIS based on his observation that, at the time, existing intelligence tests for adults were merely adaptations of tests for children and had little face validity for older age groups.

• Since 1939, three scales have been developed and subsequently revised, to measure intellectual functioning of children and adults. The Wechsler Adult Intelligence Scale-III (WAIS-III) is intended for use with adults. The Wechsler Intelligence Scale for Children-III (WISC-III) is designed for children ages 6 - 16, while the Wechsler Preschool and Primary Scale of Intelligence-R (WPPSI-R) is designed for children age 4 - 6 1/2 years.

(Retrieved www.iupui.edu)

WISC-IVAdministration and Scoring

• The procedures for administering and scoring the three Wechsler scales are similar. Each test has two batteries of subtests grouped into two general areas: 1) Verbal scales; and 2) Performance scales. The Verbal scales measure general knowledge, language, reasoning, and memory skills, while the Performance scales measure spatial, sequencing, and problem-solving skills.

• The tests are administered to individual examinees by trained examiners, using a complex set of test materials. Testing requires approximately ninety minutes. Raw scores on each test are converted to standard scores with a mean of 10 and a standard deviation of 3. Scale scores in the Verbal battery are summed and converted to a Verbal IQ score; the same is done for the Performance scale scores which yield the Performance IQ score. In turn, the Verbal and Performance IQ scores are summed and converted to obtain the Full Scale (overall) IQ score. The Verbal, Performance, and Full Scale IQ scores are normative IQs, having a mean of 100 and a standard deviation of 15. Full Scale scores beyond 130 place an individual in the “very superior” range. Scores between 120-129 are classed as “superior." Scores between 110-119 are “high average." Classifications of other scores are as follows: 90-109, average; 85-89, low average; 70-84, “borderline” mental functioning. Anything at 69 and below is considered “extremely low”; @50-69, mild mental retardation; 35- @49, moderate retardation; 20-34, severe retardation; below 20 to 25, profound retardation.

• In addition, the WISC-III and WAIS-III include supplementary Index Scales that provide measures of verbal comprehension, perceptual organization, processing speed, and working memory. The index scores also have means of 100 and standard deviations of 15.

• The manual includes procedures for determining if the examinee's performance includes areas of strengths or weaknesses. Essentially, a given test or index score must deviate from other test/index scores, or from the Verbal, performance, or overall test means by given amounts, in order for the score to be considered a significant departure from his or her performance on the other tests.

(Retrieved www.iupui.edu)

Normal Curve

How to Interpret the WISC-IV

1. Report the Child’s WISC-IV Standard Scores (FSIQ and Indexes) and Subtest Scaled Scores

2. Determine the best way to Summarize Overall Intellectual Ability3. Determine Whether each of the Four Indexes is Unitary and Thus

Interpretable4. Determine Normative Strengths and Normative Weaknesses in

the Index Profile5. Determine Personal Strengths and Personal Weaknesses in the

Index Profile 6. Interpret Fluctuations in the Child’s Index Profile7. (Optional) Conduct Clinical Comparisons when Supplemental WIC-

IV Subtests are Administered8. (Optional) Determine Whether the Difference Between the Child’s

GAI and Cognitive Proficiency Index (CPI) is Unusually Large

(Flanagan & Kaufman, 2009)

WISC-IV• The WISC-IV's four-index framework is reminiscent of the four

factors of the WISC-III, but with important differences. Some Indices of the WISC-IV have different names, and some have different or new subtests. All Index scores, except for the Processing Speed Index (PSI), are calculated on different subtests from their related factors on the WISC-III. The WISC-IV Technical Manual describes the abilities that each Index measures .

• The Verbal Comprehension Index (VCI) is 3 measure of verbal concept formation, verbal reasoning, and knowledge acquired from one's environment. The Perceptual Reasoning Index (PRI) is a measure of perceptual and fluid reasoning, spatial processing, and visual-motor integration. The Working Memory Index (WMI) is a measure of the child's working memory abilities, requiring temporarily retaining information in memory, performing some operation or manipulation with it, and producing a result. The Processing Speed Index (PSI) provides a measure of the child's ability to quickly and correctly scan, sequence, or discriminate simple visual information.

(Beal, 2004)

Subtest and Supplemental Subtests of the WISC-IV

Verbal Comprehension Subtests-• Similarities: The child is presented with two words that represent

common objects or concepts and describes how they are similar. This measures verbal concept formation and reasoning.

• Vocabulary: For picture items, the child names the object presented visually. For verbal items, the child defines words that are presented visually and orally. This measures word knowledge and verbal concept formation.

• Comprehension: The child answers questions based on their understanding of general principles and social situations. This measures verbal reasoning and conceptualization, verbal comprehension and expression, the ability to evaluate and use past experience, and the ability to demonstrate practical knowledge and judgment.

• (Information): The child answers questions that addresses a broad range of general knowledge topics. This measures the ability to acquire, retain, and retrieve general factual information.

(www.helloq.com)

Subtest and Supplemental Subtests Continued…

Perceptual Reasoning Subtests-• Block Design: While viewing a constructed model or picture, the

child uses red and white blocks to re-create the design within a specific time limit. This measures the ability to analyze and synthesize abstract visual stimuli.

• Picture Concepts: The child is presented with two or three rows of pictures and chooses one picture from each row to form a group with a common characteristic. This measures abstract, categorical reasoning ability.

• Matrix Reasoning: The child views an incomplete matrix or series and selects the response option that completes the matrix of series. This measures fluid intelligence, broad visual intelligence, classification and spatial ability, knowledge of whole-part relationships, simultaneous processing, and perceptual organization.

• (Picture Completion): Working within a specific time limit, the child views a picture with an important part missing and identifies the missing part. This measures visual perception and organization, concentration, and visual recognition of essential details of objects.

(www.helloq.com)

Subtest and Supplemental Subtests Continued…

Working Memory Subtest-• Digit Span: Digit Span Forward-the child is read a sequence of

numbers and recalls the number in the same order. Digit Span Backwards- the child is read a sequence of numbers and recalls the numbers in reverse order. This measures working memory, mental manipulation, cognitive flexibility, rote memory and learning, attention, and encoding.

• Letter Number Sequencing: the child is read a sequence of numbers and letters and recalls the numbers in ascending order and the letters in alphabetical order. This measures sequential processing, mental manipulation, attention, concentration, memory span, and short-term auditory memory.

• (Arithmetic): working within a specific time-limit, the child mentally solve a series of arithmetic problems. The measures mental manipulation, concentration, attention, short- and long term memory, numerical reasoning ability, and mental alertness.

(www.helloq.com)

Subtest and Supplemental Subtests Continued…

Processing Speed Subtest-• Coding: The child copies symbols that are paired with simple

geometric shapes or numbers. Using a key, the child draws each symbol in its corresponding shape or box within a specific time limit. This measures processing speed, short-term visual memory, learning ability, psychomotor ability, visual perception, visual-motor coordination, and visual scanning ability. The child completes this subtest using a response booklet, and not on her/his digital devise.

• Symbol Search: working within a specific time limit, the child scans a search group and indicates whether one of the symbols in the target group matches. This measures processing speed, short-term visual memory, visual-motor coordination, cognitive flexibility, visual discrimination, psychomotor speed, and speed of mental operation. The child completes this subtest using a response booklet, and not on her/his digital devise.

• Cancellation: The child scans both a random and structured arrangement of pictures, and marks target pictures within a specific time limit. This measures processing speed, visual selective attention, vigilance, perceptual speed, and visual-motor ability. The child completes this subtest using a response booklet, and not her/his digital devise.

(www.helloq.com)

Directions for Scoring for the WISC-IV• Calculate chronological age. Do not round up to nearest month.• Raw scores are totaled on each page of the record sheet. Copy raw scores into front

cover.• Tables in examiner’s manual allow for conversion from raw score to scaled score using

age-based norms (Mean 10, SD 3).• Scaled scores for 10 core tests are summed to yield a composite Full Scale IQ score

(Mean 100, SD 15).• Scaled scores contributing to each index are summed and converted to composite

scores using tables in examiner’s manual (Mean 100, SD 15).• Inside cover provides analysis of discrepancy among scores and strength/weakness

profile

Reliability and Validity for the WISC-IV• Using factor analysis, studies show that WISC subtests correlate more highly with

other subtest in the same index than subtests in different indices.• Full scale IQ scores from the WISC-IV are highly correlated with IQ scores from other

common IQ tests including: WISC-III, WPPSI-III, WAIS-III, WASI, WIAT-II, and CMS.• The examiner’s manual also presents evidence that the WISC-IV differentiates

children who have been diagnosed with mild/moderate mental retardation, ADHD, traumatic brain injury, autism, Asperger’s Syndrome, expressive language disorder, and giftedness.

• Using the split-half method, internal reliability for subtests ranged from .79 to .90.

• 243 children in the norm sample were tested a second time to evaluate test-retest reliability. Reliability coefficients ranged from .76 on picture concepts to .92 on vocabulary.

(www.iupui.edu)

WPPSI-IIIOverview The WPPSI-IV was made in response to the

increasing need for preschool assessment. (1967) The WPPSI-IV is an individually administered intelligence test for children between the ages of 2:6 - 7:7 that can be completed without reading or writing. The test is split into two different age bands: 2:6 - 3:11 & 4:0 - 7:7Each consists of different subtests for each age band. *Based on national sample from December 2010 through May 2012

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WPPSI-IV WPPSI - IV Wechsler Preschool & Primary Scale of

Intelligence - IV Purpose Description Population Test Results Reliability Standardization Validity The WPPSI-IV is an individually administered intelligence test that assesses a child’s current cognitive abilities in both verbal and nonverbal areas.

*The Verbal subtests assess the child’s ability toprocess and recall verbal material and to use language to express ideas. *The Performance subtests use appealing, age-appropriate materials and evaluate nonverbal reasoning, visual-spatial perception, and ability to process visual material. *Visual-motor integration and efficiency of visual processing are measured by Processing Speed subtests.

(http://prezi.com)

WPPSI-IV (index and subtests)

The Wechsler Preschool and Primary Scale of Intelligence consist of 14 subtests.

They are designated as one of three types: core, supplemental, or optional. The core subtests are required for the computation of the Verbal, Performance, and Full Scale IQ. The supplemental subtests provide additional information about cognitive abilities or can be used as replacement for inappropriate subtests. The optional subtests provide additional information about cognitive functioning but cannot be used as replacements for core subtests.

Directions for Scoring the WPPSI-IV

Reliability of the WPPSI-IV– Overall Reliability Average for each component of the

test: Verbal-.95, Performance-.93, Processing Speed-.89, Full Scale-.96, General Language-.93.

Test/Retest ranged from .84-.92 Test Content:Lit Reviews & Expert ReviewsResponse Processes:Lit Reviews, Expert Consultation, Empirical examinationsInternal Structure: Subtest level--.89-.96Relationship to other Measures: WISC-III, DAS, CMS Interpretations When would it be useful? The WPPSI-IV provides information about a child’s cognitive functioning.

(http://prezi.com)

WPPSI-IV

WPPSI–IV Score Reports Automatically converts total raw scores to

subtest scaled scores Automatically converts sums of scaled scores to

composites scores, including the FSIQ and numerous index scores

Provides strengths and weakness analysis at the index and subtest levels

Performs score comparisons at the index and subtest levels

Generates score reports with tables and graphs

(http://pearsonclinical.com)

WAIS-IV The current version of the test, the WAIS-IV,

which was released in 2008, is composed of 10 core subtests and five supplemental subtests, with the 10 core subtests comprising the Full Scale IQ. With the new WAIS-IV, the verbal/performance subscales from previous versions were removed and replaced by the index scores. The General Ability Index (GAI) was included, which consists of the Similarities, Vocabulary and Information subtests from the Verbal Comprehension Index and the Block Design, Matrix Reasoning and Visual Puzzles subtests from the Perceptual Reasoning Index. The GAI is clinically useful because it can be used as a measure of cognitive abilities that are less vulnerable to impairments of processing and working memory.

(http://en.wikipedia.org)

WAIS-IV (index and subtests)

There are four index scores representing major components of intelligence:– Verbal Comprehension Index (VCI)– Perceptual Reasoning Index (PRI)– Working Memory Index (WMI)– Processing Speed Index (PSI)

Two broad scores are also generated, which can be used to summarize general intellectual abilities:– Full Scale IQ (FSIQ), based on the total combined

performance of the VCI, PRI, WMI, and PSI– General Ability Index (GAI), based only on the six

subtests that the VCI and PRI comprise.

VCI

Similarities: measures abstract verbal reasoning.

Vocabulary: measures the degree to which one has learned, been able to comprehend and verbally express vocabulary.

Information: measures the degree of general information acquired from culture

(Comprehension): measures the ability to deal with abstract social conventions, rules and expressions

PRI

Block Design: measures spatial perception, visual abstract processing, and problem solving

Matrix Reasoning: measures nonverbal abstract problem solving, inductive reasoning, spatial reasoning

Visual Puzzles: measures spatial reasoning (Picture Completion): measures the ability

to quickly perceive visual details (Figure Weights): measures quantitative

and analogical reasoning

WMI

Digit span: measures attention, concentration, mental control

Arithmetic: measures concentration while manipulating mental mathematical problems

(Letter-Number Sequencing): measures attention, concentration, mental control

PSI

Symbol Search: measures visual perception/analysis, scanning speed

Coding: measures visual-motor coordination, motor and mental speed, visual working memory

(Cancellation): measures visual-perceptual speed

WAIS-IV Standardization: “The WAIS-IV was standardized on a sample of

2,200 people in the United States ranging in age from 16 to 90. An extension of the standardization has been conducted with 688 Canadians in the same age range. The median Full Scale IQ is centered at 100, with a standard deviation of 15. In a normal distribution, the IQ range of one standard deviation above and below the mean (i.e., between 85 and 115) is where approximately 68% of all adults would fall.”

Reliability and Validity: The Wechsler Adult Intelligence is a well-established scale and it has fairly high consistency. Over a two to twelve week time period, the test-retest reliabilities ranged from 0.70 (7 subscales) to 0.90 (2 subscales). Interscorer coefficients were very high, all being above 0.90. According to the test manual, the instrument targets three are – psychoeducational disability, neuropsychiatic and organic dysfunction, and giftedness. The WAIS correlated highly with the Stanford-Binet IV test (0.88) and had high concordance with various measures: memory, language, dexterity, motor speed, attention, and cognitive ability.

(www.psyresources.com)

Reference

Beal, A. L. (2004). Wechsler intelligence scale for children. Canadian Journal of School

Psychology, 19(1), 221-234. Retrieved from http://search.proquest.com/docview/224371618?accountid=14375

Flanagan, D. P., and Kaufman, A.S. (2009). Essentials of WISC-IV (second edition). John

Wiley & Sons, Inc., Hoboken: New Jersey.

Lingenfelter, Josh. (2012). WPPSI-IVRetrieved from http://prezi.com/dyudi9xzjrgx/wppsi-iv/

Retrieved from http://www.helloq.com/overview/the-q-interactive-library/wisc-iv.html ,

February 2014.

Retrieved from http://www.iupui.edu/~flip/wechsler.html, February 2014. WPPSI-IVRetrieved from http://pearsonclinical.com

Wechslar, David. (2013). Retrieved from http://www.psyresources.com

Wikipedia. (2014). Wechsler Adult Intelligence Scale. Retrieved from http://en.wikipedia.org/wiki/Wechsler_Adult_Intelligence_Scale