The Wechsler
By Jill Hutzel and K.W.
The Wechsler intelligence scales were developed by Dr. David Wechsler,
a clinical psychologist at Bellevue Hospital. His initial test, the WechslerBellevue 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.
Administration 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; 8589, 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.
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 Ability
3. Determine Whether each of the Four Indexes is Unitary and Thus
4. Determine Normative Strengths and Normative Weaknesses in the Index
5. Determine Personal Strengths and Personal Weaknesses in the Index
6. Interpret Fluctuations in the Child’s Index Profile
7. (Optional) Conduct Clinical Comparisons when Supplemental WIC-IV
Subtests are Administered
8. (Optional) Determine Whether the Difference Between the Child’s GAI and
Cognitive Proficiency Index (CPI) is Unusually Large
• 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.
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.
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.
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, visualmotor 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.
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.
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 - 7:7
Each consists of different subtests for each age band. *Based on
national sample from December 2010 through May 2012
WPPSI - IV Wechsler Preschool & Primary Scale of
Intelligence - IV Purpose Description Population Test
Results Reliability Standardization Validity The WPPSIIV 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 to
process and recall verbal material and to use language
to express ideas.
*The Performance subtests use appealing, ageappropriate 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.
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 WPPSIIV
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 Reviews
Response Processes:
Lit Reviews, Expert Consultation,
Empirical examinations
Internal Structure:
Subtest level--.89-.96
Relationship to other Measures:
WISC-III, DAS, CMS Interpretations When would it be
useful? The WPPSI-IV provides information about a
child’s cognitive functioning.
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
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.
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.
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
Block Design: measures spatial perception,
visual abstract processing, and problem solving
Matrix Reasoning: measures nonverbal abstract
problem solving, inductive reasoning, spatial
Visual Puzzles: measures spatial reasoning
(Picture Completion): measures the ability to
quickly perceive visual details
(Figure Weights): measures quantitative and
analogical reasoning
Digit span: measures attention,
concentration, mental control
 Arithmetic: measures concentration while
manipulating mental mathematical
 (Letter-Number Sequencing): measures
attention, concentration, mental control
Symbol Search: measures visual
perception/analysis, scanning speed
 Coding: measures visual-motor
coordination, motor and mental speed,
visual working memory
 (Cancellation): measures visual-perceptual
Reliability and Validity:
“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.”
The Wechsler Adult Intelligence is a wellestablished 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.
Beal, A. L. (2004). Wechsler intelligence scale for children. Canadian Journal of School
Psychology, 19(1), 221-234. Retrieved from
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-IV
Retrieved from
Retrieved from ,
February 2014.
Retrieved from, February 2014.
Retrieved from
Wechslar, David. (2013). Retrieved from
Wikipedia. (2014). Wechsler Adult Intelligence Scale. Retrieved from