Wechsler Adult Intelligence Scale
Wechsler Adult Intelligence Scale
Definition
The Wechsler adult intelligence scale (WAIS) is an individually administered measure of intelligence, intended for adults aged 16–89.
Purpose
The WAIS is intended to measure human intelligence reflected in both verbal and performance abilities. Dr. David Wechsler, a clinical psychologist , believed that intelligence is a global construct, reflecting a variety of measurable skills and should be considered in the context of the overall personality. The WAIS is also administered as part of a test battery to make inferences about personality and pathology, both through the content of specific answers and patterns of subtest scores.
Besides being utilized as an intelligence assessment, the WAIS 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 is also administered for diagnostic purposes. Intelligence quotient (IQ) scores reported by the WAIS can be used as part of the diagnostic criteria for mental retardation , specific learning disabilities, and attention-deficit/hyperactivity disorder (ADHD).
Precautions
The Wechsler intelligence scales are not considered adequate measures 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 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.
Description
The Wechsler intelligence tests , which include the WAIS, the WISC, and the WPPSI (Wechsler preschool and primary scale of intelligence), are the most widely used intelligence assessments and among the most widely used neuropsychological assessments. Wechsler published the first version of the WAIS in 1939, initially called the Wechsler-Bellevue. The newest version is the WAIS-III (the third edition, most recently updated in 1997). Since Wechsler’s death in 1981, the Wechsler tests have been revised by the publisher, the Psychological Corporation.
The theoretical basis for the WAIS and the other Wechlser scales came from Wechsler’s belief that intelligence is a complex ability involving a variety of skills. Because intelligence is multifaceted, Wechsler believed, a test measuring intelligence must reflect this multitude of skills. After dividing intelligence into two major types of skills—verbal and performance—Wechsler utilized the statistical technique of factor analysis to
determine specific skills within these two major domains. These more specific factors formed the basis of the Wechsler subtests.
The WAIS-III consists of 14 subtests and takes about 60–75 minutes to complete. The test is taken individually, with a test administrator present to give instructions. Each subtest is given separately, and proceeds from very easy items to very difficult ones. There is some flexibility in the administration of the WAIS—the administrator may end some subtests early if test takers seem to reach the limit of their capacity. Tasks on the WAIS include questions of general knowledge, traditional arithmetic problems, a test of vocabulary, completion of pictures with missing elements, arrangements of blocks and pictures, and assembly of objects.
The WAIS is considered to be a valid and reliable measure of general intelligence. When undergoing reliability and validity studies, other intelligence tests are often compared to the Wechsler scales. It is regularly used by researchers in many areas of psychology as a measure of intelligence. Research has demonstrated correlations between WAIS IQ scores and a variety of socioeconomic, physiological, and environmental characteristics.
The WAIS has also been found to be a good measure of both fluid and crystallized intelligence. Fluid intelligence refers to inductive and deductive reasoning, skills considered to be largely influenced by neurological and biological factors. In the WAIS, fluid intelligence is reflected in the performance subtests. Crystallized intelligence refers to knowledge and skills that are primarily influenced by environmental and sociocultural factors. In the WAIS, crystallized intelligence is reflected in the verbal subtests. Wechsler himself did not necessarily divide overall intelligence into these two types. However, the consideration of fluid and crystallized intelligence as two major categories of cognitive ability has been a focus for many intelligence theorists.
The Wechshler scales were originally developed and later revised using standardization samples. The samples were meant to be demographically representative of the United States population at the time of the standardization.
Results
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. Wechsler pioneered the use of deviation IQ scores, allowing test takers to be compared to others of different as well as the same age. WAIS scores are sometimes converted into percentile ranks. The verbal and performance IQ scores are based on scores on the 14 subtests. The 14 subtest scores have a mean of 10 and a standard deviation of three. The WAIS also elicits four indices, each based on a different set of subtests: verbal comprehension, perceptual organization, working memory, and processing speed.
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.
The verbal IQ
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
KEY TERMS
Factor Analysis —A statistical method for summarizing relationships between variables. With the WAIS, items that correlated highly with each other were considered to be part of certain factors underlying intelligence. These factors are the basis for the 14 WAIS subtests.
Indices —Scores based on performance in more than one area. On the WAIS, there are four index scores, each based on an individual’s performance in more than one subtest.
Mean —The mathematical average of all scores in a set of scores. The WAIS has been standardized to have a mean of 100.
Percentile rank —The point at which a given percentage of people fall at or below the individual’s test score being calculated. For example, if a person’s test score was at the 60th percentile, 40% of other test takers received a higher score, while 60% received a score that was at or below that of the test taker.
Standard deviation —A measure of variability in a set of scores. The WAIS has been standardized to have a standard deviation of 15.
Standardization —The administration of a test to a sample group of people for the purpose of establishing scoring norms. Prior to the publication of each version of the WAIS, it is standardized.
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
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.
See alsoStanford-Binet Intelligence Scales.
Resources
BOOKS
Groth-Marnat, Gary. Handbook of Psychological Assessment,3rd edition. New York: John Wiley and Sons, 1997.
Kline, Paul. The Handbook of Psychological Testing. New York: Routledge, 1999.
McGrew, Kevin S., and Dawn P. Flanagan. The Intelligence Test Desk Reference. Needham Heights, MA: Allyn and Bacon, 1998.
Ali Fahmy, Ph.D.
Wechsler adult intelligence scale
Wechsler adult intelligence scale
Definition
The Wechsler adult intelligence scale (WAIS) is an individually administered measure of intelligence, intended for adults aged 16–89.
Purpose
The WAIS is intended to measure human intelligence reflected in both verbal and performance abilities. Dr. David Wechsler, a clinical psychologist , believed that intelligence is a global construct, reflecting a variety of measurable skills and should be considered in the context of the overall personality. The WAIS is also administered as part of a test battery to make inferences about personality and pathology, both through the content of specific answers and patterns of subtest scores.
Besides being utilized as an intelligence assessment, the WAIS 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 is also administered for diagnostic purposes. Intelligence quotient (IQ) scores reported by the WAIS can be used as part of the diagnostic criteria for mental retardation , specific learning disabilities, and attention-deficit/hyperactivity disorder (ADHD).
Precautions
The Wechsler intelligence scales are not considered adequate measures 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 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.
Description
The Wechsler intelligence tests , which include the WAIS, the WISC, and the WPPSI (Wechsler preschool and primary scale of intelligence), are the most widely used intelligence assessments and among the most widely used neuropsychological assessments. Wechsler published the first version of the WAIS in 1939, initially called the Wechsler-Bellevue. The newest version is the WAIS-III (the third edition, most recently updated in 1997). Since Wechsler's death in 1981, the Wechsler tests have been revised by the publisher, the Psychological Corporation.
The theoretical basis for the WAIS and the other Wechlser scales came from Wechsler's belief that intelligence is a complex ability involving a variety of skills. Because intelligence is multifaceted, Wechsler believed, a test measuring intelligence must reflect this multitude of skills. After dividing intelligence into two major types of skills—verbal and performance—Wechsler utilized the statistical technique of factor analysis to determine specific skills within these two major domains. These more specific factors formed the basis of the Wechsler subtests.
The WAIS-III consists of 14 subtests and takes about 60–75 minutes to complete. The test is taken individually, with a test administrator present to give instructions. Each subtest is given separately, and proceeds from very easy items to very difficult ones. There is some flexibility in the administration of the WAIS—the administrator may end some subtests early if test takers seem to reach the limit of their capacity. Tasks on the WAIS include questions of general knowledge, traditional arithmetic problems, a test of vocabulary, completion of pictures with missing elements, arrangements of blocks and pictures, and assembly of objects.
The WAIS is considered to be a valid and reliable measure of general intelligence. When undergoing reliability and validity studies, other intelligence tests are often compared to the Wechsler scales. It is regularly used by researchers in many areas of psychology as a measure of intelligence. Research has demonstrated correlations between WAIS IQ scores and a variety of socioeconomic, physiological, and environmental characteristics.
The WAIS has also been found to be a good measure of both fluid and crystallized intelligence. Fluid intelligence refers to inductive and deductive reasoning, skills considered to be largely influenced by neurological and biological factors. In the WAIS, fluid intelligence is reflected in the performance subtests. Crystallized intelligence refers to knowledge and skills that are primarily influenced by environmental and sociocultural factors. In the WAIS, crystallized intelligence is reflected in the verbal subtests. Wechsler himself did not divide overall intelligence into these two types. However, the consideration of fluid and crystallized intelligence as two major categories of cognitive ability has been a focus for many intelligence theorists.
The Wechshler scales were originally developed and later revised using standardization samples. The samples were meant to be demographically representative of the United States population at the time of the standardization.
Results
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. Wechsler pioneered the use of deviation IQ scores, allowing test takers to be compared to others of different as well as the same age. WAIS scores are sometimes converted into percentile ranks. The verbal and performance IQ scores are based on scores on the 14 subtests. The 14 subtest scores have a mean of 10 and a standard deviation of three. The WAIS also elicits four indices, each based on a different set of subtests: verbal comprehension, perceptual organization, working memory, and processing speed.
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.
The verbal IQ
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
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.
See also Stanford-Binet intelligence scales
Resources
BOOKS
Groth-Marnat, Gary. Handbook of Psychological Assessment, 3rd edition. New York: John Wiley and Sons, 1997.
Kline, Paul. The Handbook of Psychological Testing. New York: Routledge, 1999.
McGrew, Kevin S., and Dawn P. Flanagan. The Intelligence Test Desk Reference. Needham Heights, MA: Allyn and Bacon, 1998.
Ali Fahmy, Ph.D.
Wechsler Intelligence Scale for Children
Wechsler Intelligence Scale for Children
Definition
The Wechsler Intelligence Scale for Children, often abbreviated as WISC, is an individually administered measure of intelligence intended for children aged six years to 16 years and 11 months.
Purpose
The WISC is designed to measure human intelligence as reflected in both verbal and nonverbal (performance) abilities. David Wechsler, the author of the test, believed that intelligence has a global quality that reflects a variety of measurable skills. He also thought that it should be considered in the context of the person's overall personality.
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.
Precautions
The Wechsler intelligence scales are not considered adequate measures of extreme intelligence (IQ scores below 40 and above 160). The scoring process does not allow for scores outside this range for test takers at particular ages. Wechsler himself was even more conservative, stressing that his scales were not appropriate for people with IQs below 70 or above 130. Despite this restriction, many people use the WISC as a measure of the intelligence of gifted children, who typically score above 130. The age range for the WISC overlaps with that of the Wechsler Adult Intelligence Scale (WAIS) for people between 16 and 17 years of age, but experts suggest that the WISC provides a better measure for people in this age range.
Administration and scoring of the WISC require a competent administrator who must be able to interact and communicate with children of different ages and must know test protocol and specifications. WISC administrators must receive training in the proper use of the instrument and demonstrate awareness of all test guidelines.
Description
The Wechsler intelligence tests , which include the WISC, the WAIS, and the WPPSI (Wechsler Preschool and Primary Scale of Intelligence), are the most widely used intelligence and neuropsychological assessments. The first version of the WISC was written in 1949 by David Wechsler. The newest version of the WISC is the WISC-III (Wechsler Intelligence Scale for Children-Third Edition, most recently updated in 1991). Since Wechsler's death in 1981, the tests have been revised by their publisher, the Psychological Corporation.
The theoretical basis for the WISC and the other Wechsler scales is Wechsler's belief that human intelligence is a complex ability involving a variety of skills. Because intelligence is multifaceted, Wechsler believed, a test measuring intelligence must reflect this diversity. After dividing intelligence into two major types of skills—verbal and performance—Wechsler used a statistical technique called factor analysis to determine which specific skills fit within these two major domains.
The current version of the WISC (the WISC-III) consists of 13 subtests and takes between 50 and 75 minutes to complete. The test is taken individually, with an administrator present to give instructions. Each subtest is given separately. There is some flexibility in the administration of the WISC—the administrator may end some subtests early if the test taker appears to have reached the limit of his or her capacity. Tasks on the WISC include questions of general knowledge, traditional arithmetic problems, English vocabulary, completion of mazes, and arrangements of blocks and pictures.
Children who take the WISC are scored by comparing their performance to other test takers of the same age. The WISC yields three IQ (intelligence quotient) scores, based on an average of 100, as well as subtest and index scores. WISC subtests measure specific verbal and performance abilities. The Wecshler scales were originally developed and later revised using standardization samples. The samples were meant to be representative of the United States population at the time of standardization.
The WISC is considered to be a valid and reliable measure of general intelligence in children. It is regularly used by researchers in many areas of psychology and child development as a general measure of intelligence. It has also been found to be a good measure of both fluid and crystallized intelligence. Fluid intelligence refers to inductive and deductive reasoning, skills that are thought to be largely influenced by neurological and biological factors. Fluid intelligence is measured by the performance subtests of the WISC. Crystallized intelligence refers to knowledge and skills that are primarily influenced by environmental and sociocultural factors. It is measured by the verbal subtests of the WISC. Wechsler himself did not divide overall intelligence into these two types. The definition of fluid and crystallized intelligence as two major categories of cognitive ability, however, has been a focus of research for many intelligence theorists.
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.
Results
WISC 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.
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.
See also Stanford-Binet intelligence scales
Resources
BOOKS
Groth-Marnat, Gary. Handbook of Psychological Assessment. 3rd edition. New York: John Wiley and Sons, 1997.
Kline, Paul. The Handbook of Psychological Testing. New York: Routledge, 1999.
McGrew, Kevin S., and Dawn P. Flanagan. The Intelligence Test Desk Reference. Needham Heights, MA: Allyn and Bacon, 1998.
Ali Fahmy, Ph.D.
Wechsler Intelligence Test
Wechsler intelligence test
Definition
The Wechsler intelligence tests are a widely used series of intelligence tests developed by clinical psychologist David Wechsler.
Purpose
The Wechsler Intelligence Scales for Children (regular, revised, and third edition) and Wechsler Preschool and Primary Scale of Intelligence are used as tools in school placement, in determining the presence of a learning disability or a developmental delay , in identifying giftedness, and in tracking intellectual development. They are often included in neuropsychological testing to assess the brain function of individuals with neurological impairments.
Description
The most distinctive feature of the Wechsler tests is their division into a verbal section and a nonverbal (or performance) section, with separate scores available for each subsection. All of the Wechsler scales are divided into six verbal and five performance subtests. The complete test takes 60 to 90 minutes to administer. Verbal intelligence, the component most often associated with academic success, implies the ability to think in abstract terms using either words or mathematical symbols. Performance intelligence suggests the ability to perceive relationships and fit separate parts together logically into a whole. The inclusion of the performance section in the Wechsler scales is especially helpful in assessing the cognitive ability of non-native speakers and children with speech and language disorders . The test can be of particular value to school psychologists screening for specific learning disabilities because of the number of specific subtests that make up each section.
The Wechsler Preschool and Primary Scales of Intelligence (WPPSI) have traditionally been geared toward children ages four to six years old, although the newest version of the test extends the age range down to three years and upward to seven years three months. The verbal section covers the following areas: general information (food, money, the body, etc.), vocabulary (definitions of increasing difficulty), comprehension (responses to questions), arithmetic (adding, subtracting, counting), sentences (repeating progressively longer sentences), and similarities (responding to questions such as "How are a pen and pencil alike?"). The performance section includes picture completion, copying geometric designs, using blocks to reproduce designs, working through a maze, and building an animal house from a model.
The Wechsler Intelligence Scale for Children (WISC) is designed for children and adolescents ages six to 16. Its makeup is similar to that of the Preschool Scale. Differences include the following: geometric designs are replaced by assembly of three-dimensional objects; children arrange groups of pictures to tell simple stories; they are asked to remember and repeat lists of digits; a coding exercise is performed in place of the animal house; mazes are a subtest. For all of the Wechsler scales (which also include the Wechsler Adult Intelligence Scale, or WAIS), separate verbal and performance scores, as well as a total score, are computed. These are then converted using a scale divided into categories (such as average and superior), and the final score is generally given as one of these categories rather than as a number or percentile ranking.
The Wechsler Intelligence Scales are standardized tests, meaning that as part of the test design, they were administered to a large representative sample of the target population, and norms were determined from the results. The scales have a mean, or average, standard score of 100 and a standard deviation of 15. The standard deviation indicates how far above or below the norm the subject's score is. For example, a ten-year-old is assessed with the WISC-III scale and achieves a full-scale IQ score of 85. The mean score of 100 is the average level at which all 10-year-olds in the representative sample performed. This child's score would be one standard deviation below that norm.
While the full-scale IQ score provides a reference point for evaluation, it is only an average of a variety of skill areas. A trained psychologist evaluates and interprets an child's performance on the scale's subtests to discover their strengths and weaknesses and offer recommendations based upon these findings.
Risks
The only known risk of the Wechsler intelligence tests is that the results are misused or are given undue weight.
Parental concerns
Results of intelligence tests should not be considered a complete indication of a child's future path. They are most useful in determining children who may need special attention, either because of disability or because of giftedness. Parents should consider the possible consequences carefully if they are considering telling their child the outcome of this or any other intelligence test.
KEY TERMS
Norms —A fixed or ideal standard; a normative or mean score for a particular age group.
Representative sample —A random sample of people that adequately represents the test-taking population in age, gender, race, and socioeconomic standing.
Standard deviation —A measure of the distribution of scores around the average (mean). In a normal distribution, two standard deviations above and below the mean includes about 95% of all samples.
Standardization —The process of determining established norms and procedures for a test to act as a standard reference point for future test results.
Resources
BOOKS
Flanagan, Dawn P., and Alan S. Kaufman. Essentials of WISC IV Assessment. Hoboken, NJ: John Wiley & Sons, 2004.
PERIODICALS
Canivez, Gary L., and Marley W. Watkins. "Long-Term Stability of the Wechsler Intelligence Scale for Children—Third Edition among Students with Disabilities." School Psychology Review 30 (Summer 2001): 438–54.
Caruso, John C., and Norman Cliff. "Increasing the Reliability of Wechsler Intelligence Scale for Children—Third Edition Difference Scores with Reliable Component Analysis." Psychological Assessment 12 (March 2000): 89–97.
Watkins, Marley W., et al. "Factor Structure of the Wechsler Intelligence Scale for Children—Third Edition among Gifted Students." Educational and Psychological Measurement 63 (October 2003): 164–72.
Tish Davidson, A.M. Paula Anne Ford-Martin
Wechsler Intelligence Test
Wechsler Intelligence Test
Definition
The Wechsler Intelligence Scales are a series of standardized tests used to evaluate cognitive abilities and intellectual abilities in children and adults.
Purpose
The Wechsler Intelligence Scales for Children (regular, revised, and third edition) and Wechsler Preschool and Primary Scale of Intelligence are used as tools in school placement, in determining the presence of a learning disability or a developmental delay, in identifying giftedness, and in tracking intellectual development.
The Wechsler Adult Intelligence Scales (regular and revised) are used to determine vocational ability, to assess adult intellectual ability in the classroom, and to determine organic deficits. Both adult and children's Wechsler scales are often included in neuropsychological testing to assess the brain function of individuals with neurological impairments.
Precautions
Intelligence testing requires a clinically trained examiner. The Wechsler scales should be administered, scored, and interpreted by a trained professional, preferably a psychologist or psychiatrist.
Description
All of the Wechsler scales are divided into six verbal and five performance subtests. The complete test takes 60-90 minutes to administer. Verbal and Performance IQs are scored based on the results of the testing, and then a composite Full Scale IQ score is computed. Although earlier editions of some of the Wechsler Scales are still available, the latest revisions are described below:
Wechsler Adult Intelligence Scale-Revised (WAIS-R)
The WAIS-R, the 1981 revision of the original Wechsler Adult Intelligence Scale, is designed for adults, age 16-74. The 11 subtests of the WAIS-R include information, digit span, vocabulary, arithmetic, comprehension, similarities, picture completion, picture arrangement, block design, object assembly, and digit symbol. An example of questions on the subtest of similarities might be: "Describe how the following pair of words are alike or the same—hamburger and pizza." A correct response would be "Both are things to eat."
Wechsler Intelligence Scale for Children, Third Edition (WISC-III)
The WISC-III subtests includes many of the same categories of subtests as the WAIS-R. In addition, there are two optional performance subtests: symbol search and mazes.
Wechsler Preschool and Primary Scale of Intelligence (WPPSI)
The WPPSI is designed for children age 4-6 1/2 years. The test is divided into six verbal and five performance subtests. The eleven subtests are presented in the following order: information, animal house and animal house retest, vocabulary, picture completion, arithmetic, mazes, geometric design, similarities, block design, comprehension, and sentences.
The 1997 Medicare reimbursement rate for psychological and neuropsychological testing, including intelligence testing, is $58.35 an hour. Billing time typically includes test administration, scoring and interpretation, and reporting. Many insurance plans cover all or a portion of diagnostic psychological testing.
Normal results
The Wechsler Intelligence Scales are standardized tests, meaning that as part of the test design, they were administered to a large representative sample of the target population, and norms were determined from the results. The scales have a mean, or average, standard score of 100 and a standard deviation of 15. The standard deviation indicates how far above or below the norm the subject's score is. For example, a ten-year-old is assessed with the WISC-III scale and achieves a full-scale IQ score of 85. The mean score of 100 is the average level at which all 10-year-olds in the representative sample performed. This child's score would be one standard deviation below that norm.
While the full-scale IQ scores provide a reference point for evaluation, they are only an average of a variety of skill areas. A trained psychologist will evaluate and interpret an individual's performance on the scale's subtests to discover their strengths and weaknesses and offer recommendations based upon these findings.
Resources
ORGANIZATIONS
American Psychological Association (APA). 750 First St. NE, Washington, DC 20002-4242. (202) 336-5700. 〈ttp://www.apa.org〉.
Catholic University of America. Washington, DC 20064. (800) 464-3742. 〈http://www.ericae.net〉.
KEY TERMS
Norms— Normative or mean score for a particular age group.
Representative sample— A random sample of people that adequately represents the test-taking population in age, gender, race, and socioeconomic standing.
Standard deviation— A measure of the distribution of scores around the average (mean). In a normal distribution, two standard deviations above and below the mean includes about 95% of all samples.
Standardization— The process of determining established norms and procedures for a test to act as a standard reference point for future test results.
Wechsler Intelligence Scales
Wechsler Intelligence Scales
A widely used series of intelligence tests developed by clinical psychologist David Wechsler.
The Wechsler Intelligence Scales are divided into two sections: verbal and nonverbal (or "performance"), with separate scores for each. Verbal intelligence, the component most often associated with academic success, implies the ability to think in abstract terms using either
words or mathematical symbols. Performance intelligence suggests the ability to perceive relationships and fit separate parts together logically into a whole. The inclusion of the performance section in the Wechsler scales is especially helpful in assessing the cognitive ability of children with speech and language disorders or whose first language is not English. The test can be of particular value to school psychologists screening for specific learning disabilities because of the number of specific subtests that make up each section.
The Wechsler Preschool and Primary Scales of Intelligence (WPPSI) have traditionally been geared toward children ages four to six, although the 1989 version of the test (WPPSI-III, 1989) extends the age range down to three years and upward to seven years, three months. The Verbal section covers the following areas: general information (food, money, the body, etc.); vocabulary (definitions of increasing difficulty); comprehension (responses to questions); arithmetic (adding, subtracting, counting); sentences (repeating progressively longer sentences); and similarities (responding to questions such as "How are a pen and pencil alike?"). The Performance section includes picture completion; copying geometric designs; using blocks to reproduce designs; working through a maze; and building an "animal house" from a model.
The Wechsler Intelligence Scale for Children (WISC), now in its second revision (WISC-III, 1991), is designed for children and adolescents ages six to sixteen. The WISC differs from the WIPPSI in the following notable ways: geometric designs are replaced by assembly of three-dimensional objects; children arrange groups of pictures to tell simple stories; they are asked to remember and repeat lists of digits; a coding exercise is performed in place of the animal house; and mazes are a subtest. For all of the Wechsler scales (which also include the Wechsler Adult Intelligence Scale, or WAIS), separate verbal and performance scores, as well as a total score, are computed. These are then converted using a scale divided into categories (such as average and superior), and the final score is generally given as one of these categories rather than as a number or percentile ranking.
See also Intelligence Quotient, I.Q. test; Stanford-Binet Intelligence Scales.