INTELLIGENCE TESTS:PURPOSE, COMMON PROCEDURES, PURPOSE

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Clinical Psychology (PSY401)

LESSON 18

INTELLIGENCE TESTS

DEFINITION

"Intelligence tests are psychological tests that are designed to measure a variety of mental functions,

such as reasoning, comprehension, and judgment".

PURPOSE

The goal of intelligence tests is to obtain an idea of the person's intellectual potential. The tests center

around a set of stimuli designed to yield a score based on the test maker's model of what makes up

intelligence. Intelligence tests are often given as a part of a battery of tests.

PRECAUTIONS WITH INTELLIGENCE TESTS

There are many different types of intelligence tests and they all do not measure the same abilities.

Although the tests often have aspects that are related with each other, one should not expect that scores

from one intelligence test, that measures a single factor, will be similar to scores on another intelligence

test that measures a variety of factors.

Also, when determining whether or not to use an intelligence test, a person should make sure that the

test has been adequately developed and has solid research to show its reliability and validity.

Additionally, psychometric testing requires a clinically trained examiner. Therefore, the test should only

be administered and interpreted by a trained professional. This is especially true in case of different tests

that measure different abilities in individuals. A person who is well trained in the administration of one

test may or may not be as well trained in the administration of another test.

CRITICISM OF INTELLIGENCE TESTS

A central criticism of intelligence tests is that psychologists and educators use these tests to distribute

the limited resources of our society. These test results are used to provide rewards such as special

classes for gifted students, admission to college, and employment.

Those who do not qualify for these resources based on intelligence test scores may feel angry as if the

tests are denying them opportunities for success. Unfortunately, intelligence test scores have not only

become associated with a person's ability to perform certain tasks, but with self-worth.

Many people are under the false assumption that intelligence tests measure a person's inborn or

biological intelligence. Intelligence tests are based on an individual's interaction with the environment

and never exclusively measure inborn intelligence.

Intelligence tests have been associated with categorizing and stereotyping people. Additionally,

knowledge of one's performance on an intelligence test may affect a person's aspirations and motivation

to obtain goals. Intelligence tests can be culturally biased against certain groups.

COMMON PROCEDURES

When taking an intelligence test, a person can expect to do a variety of tasks.

These tasks may include having to answer questions that are asked verbally, doing mathematical

problems, and doing a variety of tasks that require eye-hand coordination. Some tasks may be timed and

require the person to work as quickly as possible.

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Typically, most questions and tasks start out easy and progressively get more difficult. It is unusual for

anyone to know the answer to all of the questions or be able to complete all of the tasks. If a person is

unsure of an answer, guessing is usually allowed.

The person's raw scores on an intelligence test are typically converted to standard scores. The standard

scores allow the examiner to compare the individual's score to other people who have taken the test.

Additionally, by converting raw scores to standard scores the examiner has uniform scores and can more

easily compare an individual's performance on one test with the individual's performance on another

test.

Depending on the intelligence test that is used, a variety of scores can be obtained. Most intelligence

tests generate an overall intelligence quotient or IQ. As previously noted, it is valuable to know how a

person performs on the various tasks that make up the test. This can influence the interpretation of the

test and what the IQ means. The average of score for most intelligence tests is 100.

ADVANTAGES

In general, intelligence tests measure a wide variety of human behaviors better than any other measure

that has been developed.

They allow professionals to have a uniform way of comparing a person's performance with that of other

people who are similar in age. These tests also provide information on cultural and biological

differences among people.

Intelligence tests are excellent predictors of academic achievement and provide an outline of a person's

mental strengths and weaknesses. Many times the scores have revealed talents in many people, which

have led to an improvement in their educational opportunities. Teachers, parents, and psychologists are

able to devise individual curricula that match a person's level of development and expectations.

DISADVANTAGES

Some researchers argue that intelligence tests have serious shortcomings. For example, many

intelligence tests produce a single intelligence score. This single score is often inadequate in explaining

the multidimensional aspects of intelligence.

Another problem with a single score is the fact that individuals with similar intelligence test scores can

vary greatly in their expression of these talents. It is important to know the person's performance on the

various subtests that make up the overall intelligence test score. Knowing the performance on these

various scales can influence the understanding of a person's abilities and how these abilities are

expressed.

For example, two people have identical scores on intelligence tests. Although both people have the same

test score, one person may have obtained the score because of strong verbal skills while the other may

have obtained the score because of strong skills in perceiving and organizing various tasks.

Furthermore, intelligence tests only measure a sample of behaviors or situations in which intelligent

behavior is revealed. For instance, some intelligence tests do not measure a person's everyday

functioning, social knowledge, mechanical skills, and/or creativity.

Along with this, the formats of many intelligence tests do not capture the complexity and immediacy of

real-life situations. Therefore, intelligence tests have been criticized for their limited ability to predict

non-test or nonacademic intellectual abilities. Since intelligence test scores can be influenced by a

variety of different experiences and behaviors, they should not be considered a perfect indicator of a

person's intellectual potential.

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COMMONLY USED INTELLIGENCE TESTS

The three most commonly used intelligence tests are:

Stanford-Binet Intelligence Scales

Wechsler-Adult Intelligence Scale

Wechsler Intelligence Scale for Children

CONCEPTS OF IQ & DEVIATION IQ

Before we go into the details of the three tests, let us first understand the two basic concepts that are

employed in the tests. These are the concepts of IQ & Deviation IQ

THE INTELLIGENCE QUOTIENT (IQ or RATIO IQ)

Binet regarded the mental age (MA) as an index of mental performance. Each item successfully passed

on a Binet test signified a certain number of months' credit. At the conclusion of the test, the items

passed were added up and the MA emerged. Thus, there was nothing magical about an MA: all it meant

was the X numbers of items has been passed.

Subsequently, Stern (1938) developed the concept of intelligence quotient (1Q) to circumvent several

problems that had arisen in using the difference between the chronological age (CA) and the MA to

express deviance. At first glance, two children, one with an MA of 4 years and a CA of 5 years and

another with an MA of 14 years and a CA of 15 years, would seem to be equally deficient. However,

this is not the case, because intellectual growth is much more rapid at younger age levels. Therefore,

even though there is only a one-year discrepancy between the MA and the CA of both children, the

younger child is actually more deviant than the older one. The IQ notion enables us to perform the

following computation:

IQ=MA/CA x 100

As a result, we find that our 15-year-old has an IQ of 93, whereas the 5-year-old has an IQ of 80.These

differing scores better reflect the reality of more rapid intellectual growth at younger ages.

It should be noted that in measuring intelligence, we cannot be sure that we are dealing with equal-

interval measurement. We cannot be sure that an IQ of 50 is really twice as much as an IQ of 25 or that

our scale has an absolute zero point. We cannot add and subtract IQs. All we can do is state that a

person with an IQ of 50 is brighter than a person with an IQ of 25. All of this should serve to remind us

that IQs and MAs are merely scores.

DEVIATION IQ: Although initially appealing, the ratio IQ is significantly limited in its application to

older age groups. The reason is that a consistent (even if very high) mental age (MA) score

accompanied by an increasing chronological age (CA) score will result in a lower IQ. Thus, it may

appear that IQ has decreased over time when, in fact, one's intellectual ability has been maintained.

To deal with this problem, Wechsler introduced the concept of deviation IQ. The assumption is made

that intelligence is normally distributed throughout the population. A deviation IQ then involves a

comparison of an individual's performance on an IQ test with that of his or her age peers. Thus, the

same IQ score has a similar meaning, even if two individuals are markedly different in age (for

example, a 22-year-old versus an 80-year-old). In both cases, an IQ of 100 indicates an average level of

intellectual ability for that age group.

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THE CLINICAL ASSESSMENT OF INTELLIGENCE

In this section, we will briefly describe several of the most frequently used intelligence tests for children

and adults.

THE STANDFORD-BINET SCALE

The Stanford-Binet Intelligence Scale: Fourth Edition (SB: FE) is a standardized test that measures

intelligence and cognitive abilities in children and adults, from age two through mature adulthood.

The Stanford-Binet Intelligence Scale has a rich history.

It is a descendant of the Binet-Simon scale which was developed in 1905 and became the first

intelligence test.

The Stanford-Binet Intelligence Scale was developed in 1916 and was revised in 1937, 1960, and

1986. The present edition was published in 1986, and is called the Stanford-Binet Fourth Edition, or

SB-4.

PURPOSE

The Stanford-Binet Intelligence Scale was originally developed to help place children in appropriate

educational settings. It can help determine the level of intellectual and cognitive functioning in

preschoolers, children, adolescents and adults, and assist in the diagnosis of a learning disability,

developmental delay, mental retardation, or giftedness.

It is used to provide educational planning and placement, neuropsychological assessment, and research.

The Stanford-Binet Intelligence Scale is generally administered in a school or clinical setting.

DESCRIPTION

The Stanford-Binet Intelligence Scale is comprised of four cognitive area scores which together

determine the composite score and factor scores. The test consists of 15 subtests, which are grouped into

the four area scores.

These area scores include: Verbal Reasoning, Abstract/Visual Reasoning, Quantitative Reasoning,

and Short-Term Memory.

The composite score is considered to be what the authors call the best estimate of "g" or "general

reasoning ability" and is the sum of all of subtest scores. General reasoning ability or "g" is considered

to represent a person's ability to solve novel problems. The composite score is a global estimate of a

person's intellectual functioning.

The following is a review of the specific cognitive abilities that the four area scores measure.

1. The Verbal Reasoning area score measures verbal knowledge and understanding obtained from the

school and home learning environment and reflects the ability to apply verbal skills to new situations.

Examples of subtests comprising this factor measure skills which include: word knowledge, social

judgment and awareness, ability to isolate the inappropriate feature in visual material and social

intelligence, and the ability to differentiate essential from non-essential detail.

2. The Abstract/Visual Reasoning area score examines the ability to interpret and perform mathematic

operations, the ability to visualize patterns, visual/motor skills, and problem-solving skills through the

use of reasoning. An example of a subtest which determines the Abstract/Visual Reasoning score is a

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timed test that involves tasks such as completing a basic puzzle and replicating black and white cube

designs.

3. The Quantitative Reasoning area score measures: numerical reasoning, concentration, and knowledge

and application of numerical concepts. The Quantitative Reasoning area is combined with the

Abstract/Visual Reasoning area score to create an Abstract/Visual Reasoning Factor Score.

4. The Short-Term Memory score measures concentration skills, short-term memory, and sequencing

skills. Subtests comprising this area score measure visual short-term memory and auditory short term

memory involving both sentences and number sequences. In one subtest that measures visual short-term

memory, the participant is presented with pictures of a bead design, and asked to replicate it from

memory.

Each subtest is composed of items at varying levels of difficulty, from age 2 to adulthood. SB-4 uses an

adaptive testing procedure called multistage testing.

The examiner first gives the Vocabulary Test to determine the entry point (that is, which item to start

with) for each remaining subtest. This initial estimate of ability provides a more appropriate entry or

starting point on subsequent subtests, and is likely to result in more efficient testing, than relying

exclusively on chronological age as a guide for a starting point. Thus, not all examinees of the same age

are given the same items.

THE WECHSLER SCALES

David Wechsler used a deviation IQ concept. This approach, as we have seen, assumes that intelligence

is normally distributed and compares individuals with their age peers. In effect, it compares the

performance of a 15-year-old with that of other 15-year-olds. This method statistically establishes an IQ

of 100 as the mean for each age group. As a result, an IQ of 100 means the same thing for any person,

regardless of the person's age.

BACKGROUND OF WAIS

Earlier versions of the Stanford-Binet had a number of disadvantages that led David Wechsler in 1939

to develop the Wechsler-Bellevue Intelligence Scale. This was a test designed for adults one that

would offer items whose content was more appropriate for and more motivating to adults than the

school-oriented Binet.

In contrast to the Stanford-Binet, whose items were arranged in age levels, the Wechsler-Bellevue

Intelligence Scale grouped its items into subtests. For example, all arithmetic items were put into one

subtest and arranged in order of increasing difficulty. In addition, there was a Performance Scale and a

Verbal Scale (consisting of five and six subtests, respectively). A separate IQ for each scale could be

calculated, along with a Full Scale IQ. The systematic inclusion of performance items helped remedy

the overemphasis on verbal skills that limited the utility of the earlier Stanford-Binet with special

populations

THE WAIS-III

DESCRIPTION

A new version of the Wechsler Bellevue, known as the Wechsler Adult Intelligent Scale (WAIS), first

appeared in 1955. A revised edition (WAIS-R) was published in 1981. The most recent version, the

Wechsler Adult Intelligent Scale-Third Edition (WAIS-III), was introduced in 1997. It is an

individually administered measure of intelligence, intended for adults aged 1689.

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PURPOSE

The WAIS-III is intended to measure human intelligence reflected in both verbal and performance

abilities. Besides being utilized as an intelligence assessment, the WAIS-III is used in

neuropsychological evaluation, specifically with regard to brain dysfunction. Large differences in

verbal and nonverbal intelligence may indicate specific types of brain damage.

The WAIS-III is also administered for diagnostic purposes. Intelligence quotient (IQ) scores reported by

the WAIS-III can be used as part of the diagnostic criteria for mental retardation, specific learning

disabilities, and attention-deficit/hyperactivity disorder (ADHD).

The WAIS elicits three intelligence quotient scores, based on an average of 100, as well as subtest and

index scores. WAIS subtests measure specific verbal abilities and specific performance abilities. The

WAIS elicits an overall intelligence quotient, called the full-scale IQ, as well as a verbal IQ and a

performance IQ. The three IQ scores are standardized in such a way that the scores have a mean of 100

and a standard deviation of 15.

The WAIS also elicits four indices, each based on a different set of subtests: verbal comprehension,

perceptual organization, working memory, and processing speed.

The verbal and performance IQ scores are based on scores on the 14 subtests. The full-scale IQ is based

on scores on all of the subtests and is a reflection of both verbal IQ and performance IQ. It is considered

the single most reliable and valid score elicited by the WAIS. However, when an examinee's verbal and

performance IQ scores differ significantly, the full-scale IQ should be interpreted cautiously.

Following are 14 WAIS-Ill subtests. Seven are the verbal subsets and 7 are the performance tests:

THE VERBAL IQ is derived from scores on seven of the subtests: information, digit span,

vocabulary, arithmetic, comprehension, similarities, and letter-number sequencing. Letter-number

sequencing is a new subtest added to the most recent edition of the WAIS (WAIS-III).

The information subtest is a test of general knowledge, including questions about geography and

literature. The digit span subtest requires test takers to repeat strings of digits. The vocabulary and

arithmetic subtests are general measures of a person's vocabulary and arithmetic skills. The

comprehension subtest requires test takers to solve practical problems and explain the meaning of

proverbs. The similarities subtest requires test takers to indicate the similarities between pairs of things.

The letter-number sequencing subtest involves ordering numbers and letters presented in an unordered

sequence. Scores on the verbal subtests are based primarily on correct answers.

THE PERFORMANCE IQ is derived from scores on the remaining seven subtests: picture

completion, picture arrangement, block design, object assembly, digit symbol, matrix reasoning,

and symbol search. Matrix reasoning and symbol search are new subtests and were added to the most

recent edition of the WAIS (WAIS-III).

In the picture completion subtest, the test taker is required to complete pictures with missing elements.

The picture arrangement subtest entails arranging pictures in order to tell a story. The block design

subtest requires test takers to use blocks to make specific designs. The object assembly subtest requires

people to assemble pieces in such a way that a whole object is built. In the digit symbol subtest, digits

and symbols are presented as pairs and test takers then must pair additional digits and symbols. The

matrix reasoning subtest requires test takers to identify geometric shapes. The symbol search subtest

requires examinees to match symbols appearing in different groups. Scores on the performance subtests

are based on both response speed and correct answers.

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VERBAL SUBTESTS

PERFORMANCE SUBTESTS

Vocabulary

Picture completion

Similarities

Digital Symbol-Coding

Arithmetic

Block Design

Digit Span

Picture Arrangement

Information

Matrix Reasoning

Comprehension

Symbol Search

Letter-Number Sequencing

Object Assembly

PRECAUTIONS

The WAIS III is not considered adequate measure of extremely high and low intelligence (IQ scores

below 40 and above 160). The nature of the scoring process does not allow for scores outside of this

range for test takers at particular ages. Wechsler himself was even more conservative, stressing that his

scales were not appropriate for people with an IQ below 70 or above 130. Also, when administering the

WAIS to people at extreme ends of the age range (below 20 years of age or above 70), caution should

be used when interpreting scores.

The age range for the WAIS III overlaps with that of the Wechsler Intelligence Scale for Children

(WISC) for people between 16 and 17 years of age, and it is suggested that the WISC provides a better

measure for this age range.

Administration and scoring of the WAIS require an active test administrator who must interact with the

test taker and must know test protocol and specifications. WAIS administrators must receive proper

training and be aware of all test guidelines.

THE WISC-III

The Wechsler Intelligence Scale for Children (WISC) was first developed in 1949 and revised in 1974

(WISC-R) The latest version, the Wechsler Intelligence Scale for Children-Third Edition WISC-III),

was published in 1991.

It is an individually administered measure of intelligence intended for children aged six years to 16

years and 11 months.

PURPOSES

The WISC is designed to measure human intelligence as reflected in both verbal and nonverbal

(performance) abilities. The WISC is used in schools as part of placement evaluations for programs for

gifted children and for children who are developmentally disabled.

In addition to its uses in intelligence assessment, the WISC is used in neuropsychological evaluation,

specifically with regard to brain dysfunction. Large differences in verbal and nonverbal intelligence

may indicate specific types of brain damage.

The WISC is also used for other diagnostic purposes. IQ scores reported by the WISC can be used as

part of the diagnostic criteria for mental retardation and specific learning disabilities. The test may

also serve to better evaluate children with attention-deficit/hyperactivity disorder (ADHD) and other

behavior disorders.

WISC III scores yield an overall intelligence quotient, called the full scale IQ, as well as a verbal IQ

and a performance IQ. The three IQ scores are standardized in such a way that a score of 100 is

considered average and serves as a benchmark for higher and lower scores. Verbal and performance IQ

scores are based on scores on the 13 subtests.

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The full scale IQ is derived from the child's scores on all of the subtests. It reflects both verbal IQ and

performance IQ and is considered the single most reliable and valid score obtained by the WISC. When

a child's verbal and performance IQ scores are far apart, however, the full scale IQ should be interpreted

cautiously.

VERBAL IQ

The child's verbal IQ score is derived from scores on six of the subtests: information, digit span,

vocabulary, arithmetic, comprehension, and similarities.

The information subtest is a test of general knowledge, including questions about geography and

literature. The digit span subtest requires the child to repeat strings of digits recited by the examiner.

The vocabulary and arithmetic subtests are general measures of the child's vocabulary and arithmetic

skills. The comprehension subtest asks the child to solve practical problems and explain the meaning of

simple proverbs. The similarities subtest asks the child to describe the similarities between pairs of

items, for example that apples and oranges are both fruits.

PERFORMANCE IQ

The child's performance IQ is derived from scores on the remaining seven subtests: picture completion,

picture arrangement, block design, object assembly, coding, mazes, and symbol search.

In the picture completion subtest, the child is asked to complete pictures with missing elements. The

picture arrangement subtest entails arranging pictures in order to tell a story. The block design subtest

requires the child to use blocks to make specific designs. The object assembly subtest asks the child to

put together pieces in such a way as to construct an entire object. In the coding subtest, the child makes

pairs from a series of shapes or numbers. The mazes subtest asks the child to solve maze puzzles of

increasing difficulty. The symbol search subtest requires the child to match symbols that appear in

different groups. Scores on the performance subtests are based on both the speed of response and the

number of correct answers.

CONCLUSION

THE CLINICAL USE OF INTELLIGENCE TESTS

It is time to take a closer look at how these tests are used in the clinical setting.

THE ESTIMATION OF GENERAL INTELLECTUAL LEVEL

The most obvious use of an intelligence test is as a means for arriving at an estimate of the patient's

general intellectual level. Often the goal is the determination of how much general intelligence "g" a

given person possesses.

Often, the question is stated a bit differently, for example, what is the patient's intellectual potential?

Posing the question in this way suggests that perhaps the person is not functioning as well as his or her

potential would indicate. The potential can form a baseline against which to measure current

achievements, thus providing information about the patient's current level of functioning.

PREDICTION OF ACADEMIC SUCCESS

There are data that demonstrate a relationship between intelligence test scores and school success. To

the extent that intelligence should logically reflect the capacity to do well in school, we are justified in

expecting intelligence tests to predict school success. Not everyone would equate intelligence with

scholastic aptitude, but the fact remains that a major function of intelligence tests is to predict school

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performance. One must remember, however, that intelligence and academic success are not

conceptually identical.

THE APPRAISAL OF STYLE

The clinical psychologists' interest is not only in the client's success or failure on particular test items

but also how that success or failure occurs. One of the major values of individual intelligence tests is

that they permit us to observe the client or patient at work. Such observations can help us greatly in

interpreting an IQ. For example, did this child do as well as possible? Was there failure-avoidance? Did

the child struggle with most items, or was there easy success? Was the child unmotivated, and could this

have detracted from the child's performance? Such questions and the ensuing interpretations breathe life

into an otherwise inert IQ score.

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