Test and Measurement
Chapter 10: The Wechsler Intelligence Scales: WAIS-IV, WISC-IV and WPPSI-III
Throughout his career, Wechsler emphasized that factors other than
intellectual ability are involved in intelligent behavior. Today, there are three
Wechsler intelligence tests, the Wechsler Adult Intelligence Scale, Fourth
Edition >n (WAIS-IV), the Wechsler Intelligence Scale for Children, Fourth
Edition (WISC-IV), and the Wechsler Preschool and Primary Scale of
Intelligence, Third Edition (WPPSI-III).
The Wechsler Intelligence Scales
The role of nonintellective factors is apparent in the Wechsler intelligence
Wechsler’s test did not directly measure nonintellective factors; it took these
factors into careful account in its underlying theory.
Wechsler (1939) also correctly noted that the Binet scale emphasis on speed,
with timed tasks scattered throughout the scale, tended to unduly handicap
Wechsler criticized the then existing Binet
Point and performance scale concepts
Differences between the Wechsler and the original Binet scales were (1)
Wechsler’s use of the point scale concept rather than an age scale and (2)
Wechsler’s inclusion of a nonverbal performance scale.
The point scale concept
o In a point scale, credits or points are assigned to each item.
o . This scale makes it easy to group items of a particular content
together, which is exactly what Wechsler did.
o Similar concept was used in the 1986 Binet scale.
o Yielded not only a total overall all score but also scores for each
The performance scale concept
o Wechsler included an entire scale that provided a measure of
nonverbal intelligence: a performance scale.
o The performance scale consisted of tasks that require a subject to do
something rather than merely answer questions
o Original Wechsler scale, however, included two separate scales.
o The verbal scale provided a measure of verbal intelligence, and the
performance scale a measure of nonverbal intelligence.
o Wechsler’s new scale was the first to offer the possibility of directly
comparing an individual’s verbal and nonverbal intelligence that is,
both the verbal and performance scales were standardized on the same sample, and the results of both scales were expressed in
o They not only measure intelligence but also provide the clinician with
a rich opportunity to observe behavior
in a standard setting.
From the Wechsler-Bellevue Intelligence Scale to the WAIS-IV
First effort to measure adult intelligence was poorly standardized.
Its normative sample consisted of a non-representative sample of 1081
whites from the eastern United States
Scales, Subtests and Indexes
Wechsler defined intelligence as the capacity to act purposefully and to adapt
to the environment.
Wechsler’s definition implies that intelligence comprises several specific
interrelated functions or elements and that general intelligence results from
the interplay of these elements.
In the WAIS-IV, Wechsler’s basic approach is maintained.
First, there are individual subtests, each of which is related to a basic
underlying skill or ability
Each of the various subtests is also part of a broader “index.”
WAIS-IV, the subtests are sorted into four indexes: verbal comprehension,
perceptual reasoning, working memory, and processing speed.
An index is created where two or more subtests are related to a basic
A Closer Look as Subtests
The vocabulary subtest
o Ability to define words
o If an individual has shown deterioration i.e., lowered performance
compared with a previously higher level) because of emotional
factors or brain damage, for example, vocabulary is one of the last
functions to be affected.
o Mild concentration difficulties lower optimal performance on
arithmetic and digit span tasks, such difficulties generally do not
affect vocabulary until they become quite severe
o Can use it to evaluate baseline or premorbid intelligence
The similarities Subtest
o Consists of paired items of increasing difficulty.
o The subject must identify the similarity between the items in each
o This subtest measures the subject’s ability to see the similarity
between apparently dissimilar objects or things. o Individuals with schizophrenia tend to give idiosyncratic concepts, or
concepts that have meaning only to them.
The arithmetic Subtest
o Contains approximately 15 relatively simple problems in increasing
order of difficulty. The ninth most difficult item is as easy as this:
“A person with $28.00 spends $.50. How much does he have
The digit span subtest
o Requires the subject to repeat digits, given at the rate of one per
second, forward and backward
o Measures short-term auditory memory and is one of the core subtests
in the working memory index
o Non-intellective factors often influence the results
The Information Subtest
o College students typically find the information subtest relatively easy
o Items appear in order of increasing difficulty.
o The information subtest involves both intellective and nonintellective
o Factors such as curiosity and interest in the acquisition of knowledge
tend influence test scores.
The comprehension Subtest
o Has three types of questions.
o The first asks the subject what should be done in a given situation, as
in, “What should you do if you find an injured person lying in the
o The second type of question asks the subject to provide a logical
explanation for some rule or phenomenon, as in, why do we bury the
o He third type asks the subject to define proverbs such as, “A journey
of 1000 miles begins with the first step.’
o Measures common sense.
o The person’s emotional disturbance interferes with his or her
judgment and results in an inappropriate response. With the
example what do you do if you find someone hurt on the side of the
The Letter Number Sequencing Subtest
o Not required to obtain an index score
o It is made up of items in which the individual is asked to reorder lists
of numbers and letters. For example, Z, 3, B, 1, 2, A, would be
reordered as 1, 2, 3, A, B, Z
o Elated to working memory and attention
The digit Symbol-Coding subtest
o Quires the subject to copy symbols o After completing a short practice sample, the subject has 120 seconds
to copy as many symbols as possibly
o The subtest measures the ability to learn unfamiliar tasks, visual
motor dexterity, degree of persistence and speed of performance
The block design subtest
o Included in nonverbal measures of intelligence
o Materials for the block design subtest include nine variously colored
o The materials also include a booklet with pictures of the blocks
arranged according to a specific geometric design or configuration
o Must arrange the blocks to reproduce increasingly difficult designs.
o The subtest provides an excellent measure of nonverbal concept
formation, abstract thinking, and neurocognitive re impairment
o It is one of the core measures of the perceptual reasoning index scale
in the WAIS-IW.
The Matrix Reasoning Subtest
o Was included in the WAIS-IV as a core subtest in the perceptual
reasoning index scale in in an e: effort to enhance the assessment of
fluid intelligence, which involves our ability to reason.
o Subject is presented with non-verbal, figural stimuli
o The task is to identify a pattern or relationship between the