The Pros and Cons of the Wechsler Adult Intelligence Scale (WAIS-III) Introduction This paper discusses the pros and cons of the Wechsler Adult Intelligence Scale (WAIS-III). First, important definitional, theoretical issues, including the nature of intelligence, a brief history, and pros and cons are discussed. Next, the development, reliability, validity, and assets and limitations of the WAIS-III are examined. This is followed by discussion of the meaning of IQ scores, use of successive level interpretation and cautions and guidelines for administration.
Last, subtests, assessing special population groups, short forms, profile forms, and what a report on intellectual assessment should contain are briefly discussed, followed by summary and conclusion. The Nature of Intelligence Intelligence is an intrapersonal phenomenon, that is inside a person and it is generally agreed that the nature of this energy is unknown. Nevertheless, it may be known by its mental products (Groth-Marnet, 1997; Wechsler, 1939). Because there are many different ways to be intelligent there have also been many different definitions proposed (see Neiser, et al. 1996 for summary). A consensus on what constitutes intelligence is generally lacking. Alfred Binet (1908), the author of one of the first modern intelligence tests, defined intelligence as the inclination to take and maintain a specific direction, and capacity to adapt to achieve a goal outcome, and the power of autocriticism (Kaplan, & Saccuzzo, 2005). In contrast, David Wechsler, the developer of the Wechsler scales, defined intelligence as the aggregate capacity to act purposefully, think rationally, and deal effectively with the environment (Wechsler, 1958 as cited in Kaplin, & Saccuzzo).
A review by Sternberg, (2005) of intelligence literature over the past century by psychologists and intelligence experts reveals two main themes, that is, that intelligence is the capacity to learn from experience and the capacity to adapt to one’s environment (Sternberg). There are also two commonly accepted theories about intelligence, 1) general intelligence, 2) multiple intelligences (Groth-Marnat). The theory of general intelligence was proposed by Spearman in 1904, when he noted that children’s school grades across different subject tests reported a significant positive correlation.
This suggested to Spearman that although there were specific abilities, there was also a global influence of intellectual ability at work, he termed, “g” for “general intelligence” (Sternberg, 1997). More recent theories of intelligence in contrast suggest that human intelligence can be best conceptualised as multiple abilities or intelligences (Kaplin, & Saccuzzo, 2005). However, a number of different intelligences have been proposed, and there is a general lack of consensus about how many intelligences there are (Sternberg, 1997).
One such theory by Thurstone (1930) proposes that there are seven components of intellect. He termed “Primary Mental Abilities”: 1. Verbal ability. 2. Verbal fluency. 3. Numerical ability. 4. Spatial ability. 5. Perceptual ability. 6. Inductive reasoning. 7. Memory (Kaplin, & Saccuzzo, 2005). Cattell (1971, 1987) on the other hand insisted that g should be split into two dimensions: fluid (gf), abilities, that represents an individual’s ability to reason, think, and acquire new knowledge, and crystallised (go) intelligence, that represents an individual’s acquired knowledge and understanding (Caruso & Cliff, 1999).
More recently, Gardner (1983) proposed seven relatively independent competencies, Linguistic, Musical, Logical-mathematical, Spatial, Bodily-kinaesthetic, Interpersonal, Intrapersonal. In addition, an intermediary stance has been adopted between g and multiple intelligences (Kaplin, & Saccuzzo). For example, Vernon (1950), suggested that there was multiple abilities as well as acknowledging a unifying g factor (Neiser, et al. , 1996). The history and Development of Testing of Intelligence Modern day intelligence testing originated in the late 19th century (Kaplin, & Saccuzzo, 2005).
Sir Francis Galton (1869, 1883) quantified traits that were assumed to be correlated, and developed the first comprehensive test of intelligence. By the end of the 19th century, the foundation was laid for modern day intelligence testing (Wicket, 1998). In 1905, the French psychologist Alfred Binet published the first modern intelligence test to identify students who needed special help in coping with the school curriculum (Neiser, et al. 1996). Shortly thereafter in 1908 and 1911, Alfred Binet and Theodore Simon published revisions of the Binet intelligence test (Wicket).
The mental age concept was adopted to express the results in adequate units. The concept is based on an individual’s performance in comparison to the average performance of individuals in a specific chronological age group (Kaplin, & Saccuzzo). A further refinement of the Stanford-Binet scale and translation (for American culture) was published in 1916 by Lewis M. Terman, who adopted Stern’s proposal that an individual’s intelligence level be measured as an intelligence quotient (I. Q. ).
The IQ score presumably represented an individual’s rate of mental development as a quotient, between “mental age” and actual “chronological age” times 100 (to remove the decimal). Terman’s test, known colloquially as the Stanford-Binet test, formed the basis for modern intelligence tests still commonly used today (e. g. , Stanford Binet test- version IV) (Kaplin, & Saccuzzo, 2005). The assessment of children expanded rapidly to the assessment of adults when the United States entered World War I in 1917.
Robert Yerkes developed the Army Alpha and Army Beta tests in order to measure the inherent abilities of literate and illiterate recruits (Enns & Retten, 1998). Pros and Cons Concerning Intelligence Testing The introduction of intelligence testing aroused considerable controversy (Kaplin, & Saccuzzo, 2005). Proponents hold that intelligence testing can assess relative strengths and weaknesses, reveal important personality variables, predict successes in life, such as scholastic performance, economic success, work success, success in parenting, avoidance of criminality, and avoidance of welfare dependence (Kaplin, & Saccuzzo; Neisser et al. 1996). Critics charge that intelligence tests are biased, especially against special population groups, ethnic minorities and the poor (Suzuki & Valencia, 1997), and information may be misused to disadvantage certain people. However, there is little evidence in records that show that IQs have been misused and that tests are biased against minorities (Kaplin, & Saccuzzo). Proponents also ague that intelligence tests may help identify the most competent members without basis for personal judgment, in a less subjective way which might be more racist than the tests (Ones, Chockalingam, & Smidt, 1995).
The History and Development of WAIS-III In 1939 David Wechsler, a clinical psychologist dissatisfied with existing measures developed the Wechsler–Bellevue Intelligence Scale/test (WBI, Enns & Redden, 1998). He came to envision intelligence both as a unitary concept (the g factor of Spearman) and as a composite of distinct abilities (as espoused by Thorndike) merging the two concepts into his theory of intelligence. Wechsler selected a number of items and procedures from existing ability tests, such as the 1937 revision of the Stanford-Binet, Army Alpha, Army Beta Test (Groth-Marnat, 1997; Flanagan, 2004).
A performance scale, measuring nonverbal intelligence, and verbal scale, measuring verbal intelligence was adopted (Kaplin, & Saccuzzo, 2005). Also, a point scale was enlisted, where a specific number of credits or points were assigned to each item (Kaplin, & Saccuzzo). In addition, the WBI met the needs of the emerging field of learning disabilities, mental retardation, and Attention-Deficit/Hyperactivity Disorder (ADHD) assessment in the 1960s, becoming the most widely used psychological tests in the United States. Nevertheless, it had a number of shortcomings, such as reliability of subtests, and poor standardisation (Groth-Marnat).
Thus it was revised in 1955 into its modern form, as the WAIS, and standardisation limitations of the earlier scales were rectified. The WAIS was further modified, revised, and restandardised in 1981 (WAIS-R), and again in 1997 (WAIS-III) (Kaplin, & Saccuzzo). Reliability and Validity of WAIS-III The WAIS-III instrument has excellent psychometric properties. It was standardized on 2,450 adult participants and stratified according to age, gender, race/ethnicity, geographic region, and education level (Kaufman, Lichtenberger, & Mclean, 2001).
The reliability coefficients of the WAIS-III are quite high, with average split-half reliability coefficients . 98, . 97, and . 94 for Full-scale, verbal, and performance IQs, respectively (Donders, Tulsky, & Zhu, 2001; Kaufman et al. ). Reliability for specific subtests are less satisfactory with most subtests in the low . 70s and . 80’s, and some are in the . 60’s (Kaufman et al. ). Test-retest coefficients are . 95, . 94, and . 88 for Full-scale, verbal, performance IQs, respectively (Kaufman et al. ).
The specific subtests are less satisfactory with the average reliabilities ranging from . 70 (object assembly), to . 93 (vocabulary) (Kaufman et al. ). The overall standard error of measurement (SEM) is low, reported at 2. 29 for the full-scale IQ, 2. 5 for the verbal IQ, with less confidence placed on performance IQ of 3. 75. (Wechsler, 2003 cited in Kaplin, & Saccuzzo, 2005). The WAIS-III is much the same test as the WAIS-R, and its validity rests primarily with its high correlation with the earlier WAIS-R and WISC, where ages overlap.
The Full scale, Verbal, and Performance IQs correlate with measure of the WISC third edition . 93, . 94, and . 86 respectively. As expected, individual subtest correlations with other tests runs lower for subtests (Kaplin, & Saccuzzo, 2005). The results of rigorous exploratory and confirmatory factor analyses also supports the construct validity (Kaufman et al. , 2001). Assets and Limitations The extended age range norms (70s to 80s), are considered an asset, as they are useful in understanding intelligence in later decades (Kaufman et al. , 2001; Wymer, Rayls, & Wagner, 2003).
There are also important procedural advancements; such as a de-emphasis on time, and extra content, such as extra subtests, for supplemental information, as well as a better representation of short-term memory. Furthermore, the four indices provide a better reflection of an individual’s cognitive abilities than the traditional Verbal and Performance IQ scores (Donders et al. , 2001; Kaufman et al. , 2001). The WAIS-III also has a substantial amount of research available to develop hypotheses, and to make relatively accurate predictions about a client (Groth-Marnat, 1997).
An important asset of the WAIS is the ability to aid in assessing personality variables through observation, and assessing the content of test item responses, evaluating information inferred from the individual’s pattern of subtest scores (Groth-Marnat). A major limitation of the WAIS-III is that it does not adequately measure extreme ranges of intelligence (e. g. , below 40 and above 160). In addition, the WAIS-III is much the same test as the WAIS-R which is based on early theories, and does not give much attention to the multiple intelligences (Kaplin, & Saccuzzo, 2005).
Another limitation is that the WAIS-III scales neglect non academic skills, such as creativity, motivational level, imagination, social acumen, and success in dealing with people that may be an advantage for success (Groth-Marnat, 1997; Sternberg, 1985). Meaning of IQ Scores The IQ score provides an accurate and broadly based measure of overall intellectual functioning, g, that reports an estimate of a person’s current level of areas of functioning (Kaplin, & Saccuzzo, 2005).
The Full-scale IQ/ Performance IQ/ Verbal IQ scores can be used to obtain the relative position of a person compared with his or her age-related peers; however, it cannot give a complete picture. In addition, the IQs are not fixed, unchangeable, or an exact measurement or an innate score, but may be influenced by a variety of factors (e. g. , achievement orientation, curiosity, culture, and the person’s interests (Groth-Marnat, 1997). Furthermore, only a limited range of abilities can be measured by the Wechsler scales, with many variables that may be considered intelligence beyond the scope of most intelligence tests (e. . , creativity, artistic, musical) (Sternberg, 1997). In addition, a high IQ scored does not necessarily mean that an individual will excel academically, or in career, because other factors may be involved, such as motivation, and support (Groth-Marnat). Cautions and Guidelines in Administration Caution should be exercised when interpreting performance data for examinees over 89 years, as norms are not available. In addition, caution needs to be exercised in interpreting results for elderly Hispanics, Asian Americans, native Americans, as there is minimal data available (Kaplin, & Saccuzzo, 2005).
Care must also be taken in administration procedures. Verbal and nonverbal reinforcement should be given to encourage motivation; however, it should not be contingent on whether a response is correct or incorrect (Flanagan, 2004). In addition, the examiner must be careful to follow the proper sequence of subtest administration, subtest starting points and discontinuance rules, and take care to accurately record responses, convert raw scores, and keep to specified time limits (Groth-Marnat, 1997; Flanagan).
Furthermore, an examinee must have adequate vision, hearing and motor functions and be fluent in English in order to permit a valid administration of the verbal and performance scale subtests (Flanagan). WAIS-III Successive Level Interpretation Procedure The purpose of the five successive-level’s approach for the Wechsler scales suggested by Groth-Marnat (1997) is to enable confirmation, disconfirmation, or alter hypotheses derived from the referral question, and from any background information. In level one the full scale IQ is nterpreted, and percentile ranks and IQ classification. Level two, involves interpretation of Verbal-Performance IQ’s if discrepancy is 12 or more points, and four factor scores if significant discrepancies exist between the mean of the four scores/indexes and relevant factor scores; and additional Groupings, (e. g. , Bannatyne’s Categories, ACID/SCAD profiles, Horn groupings, Fluid profile) if there is significant differences between means of groupings and individual grouping/category (Kaufman, 1994).
Level three involves examining the individual subtests’ strengths and weaknesses to determine fluctuation significance, and indicate this on the profile as either a strength or a weakness. Next a hypothesis is developed in relation to the meaning of subtest fluctuations, and this is integrated with any additional information (Truch, 1993). At level four, intra-subtest variability is analysed for internally inconsistencies to determine problems (e. g. , attention, anxiety), and to uncover any consistently incorrect problem answers before stating any weakness in background knowledge (Truch).
Level five involves conducting a Qualitative analysis (Groth-Marnat). WAIS-III Subtests The WAIS-III contains a performance and a verbal scale, with each subtest related to a specific skill or ability that gives valuable information about a specific skill or ability level, and used in comparison to aged or reference norms (Brookes & Weaver, 2006; Burtona, Ryan, Axelrod, & Schellenberger, 2002). The seven verbal scale subtests are (1) vocabulary, 2) similarities, 3) arithmetic, 4) digit, 5) information, 6) comprehension, 7) letter number sequencing, (an optional subtest) (Axelrod, Ryan, & Ward, 2001).
The seven performance scale subtests include 1) picture completion 2) digit symbol-coding (Ryan, Kreimer, Bartels, Tree, Schnakenberg-ott, 2006), 3) block design, 4) matrix reasoning (Kaufman, 2000 literature review), 5) picture arrangement, 6) object assembly (optional test), and 7) symbol search, (an optional test) (Ryan, et al. , 2006). The WAIS-II also has four indices derived from a factor analysis of 11 subtests (Brookes & Weaver, 2006); 1) verbal comprehension 2) perceptual organisation 3) working memory 4) processing speed.
They serve to strengthen the theoretical basis of the test and enhance the measurement of fluid reasoning (Brookes & Weaver, 2006; Burtona, et al. , 2002). Assessing Brain Damage Besides being utilised as an intelligence assessment, the WAIS is used in neuropsychological evaluation, specifically with regard to brain dysfunction (Kaplin, & Saccuzzo, 2005; Longman, 2004). The IQ scores may show large differences in verbal and nonverbal intelligence and reveal cognitive effects of brain injury that may indicate specific types of brain damage (Dori & Chelune, 2004).
Each subtest score may be tallied and compared to non-normal or brain-damaged norms to reveal deficits in brain function (Axelrod, Fichtenberg, Liethen, Czarnota, & Stuky, 2001; Crawford, Johnson, Myschalkiw, & Moore, 1997). Moreover, scores may reveal all, most, or specific differences that can help detect brain damage by whether a person’ scores generally or specifically lower than the expected score of the individual’s age, education, socioeconomic status, occupation, and other relevant areas of the individual’s history (Groth-Marnat, 1999). Assessing Special Populations
In addition to being utilised as an intelligence assessment instrument the WAIS is also administered as part of a test battery to make inferences about personality and pathology, through the content of specific answers and patterns of subtest scores (Groth-Marnat, 1997; Kaplin, & Saccuzzo, 2005). The WAIS-III may also be used to help diagnose mental retardation (mentally handicapped) based on the general acceptance of the cut off IQ score of 70 (Flynn, 2000). Adaptive functioning must also be assessed as below a set criteria to be classified as mentally retarded (Kaplin, & Saccuzzo, 2005).
In addition, it may be used to help identify gifted children, based on the general definition as having Verbal or Performance IQs of 130 or higher. The Stanford-Binet may be more effective since it has a higher ceiling than the WAIS-III (Groth-Marnat, 1997). The WAIS-III may also be part of assessment for Learning difficulties. Those that do badly on 4 subtests- arithmetic, information, coding, and digit span (AICD) indicate a possible learning difficulty (Flynn, 2000). In addition, ADHD diagnosis may also be part of assessment of the WAIS-III, by revealing an individual’s intellectual strengths and weaknesses.
For example, strengths in areas that do not require concentrated effort, and weaknesses in subtests that require focused attention such as mathematical computation and pattern recognition) may indicate the presence of ADHD (Groth-Marnat, 1997; Flanagan, 2004). Short Forms A number of WAIS-III short forms have been developed for when there are time constraints or physical constraints that prevent a full test (e. g. , all subtests may take from 65 to 95 minutes to administer) (Axelrod et al. , 2001; Brookes & Weaver, 2006). Abbreviation of full form tests is done by either reducing the number of items within individual subtests (e,g. Satz-mogel short form; Wymer et al. , 2003), or by reducing the number of subtests (Groth-Marnat, 1997). The short forms of the test have relatively high correlations reported with full-form test; however, there is less satisfactory correlation of the four index scores with FSIQ (see Axelrod et al. , 2001). Hence, results of short forms are more appropriately used as a rough indicator of intelligence, or as screening devices (e. g. , basis for more complete cognitive assessment) (Axelrod et al. ; Groth-Marnat; Silverstein, 1990). Profile Forms
The profile forms in the Appendices are useful for enabling scores to be plotted for speedy and easy observation of the test results. Furthermore, in order to provide a listing of the three IQs as well as a summary of relative strengths and weaknesses, the abilities required for the WAIS subtests are summarised on the far right side, and scaled scores are plotted in the centre. It is also cautioned that profiles should be viewed as hypotheses that may or may not be confirmed through comparisons with other subtests rather than interpretations (Groth-Marnat, 1997). What a Report on Intellectual Assessment Should Contain
A well written intellectual report should contain background information (e. g. , referral information, mental, medical history), as well as observations during the test that might affect reliability of results (e. g. , motivation). It should also contain a clear summary of all IQ scores, as well as individual subtests. In addition, it should contain a clear statement about the significant differences between scores (e. g. , performance and verbal scores), as well as an explanation about whether an individual exceeds, is in an acceptable range, or declines in comparison to a population of similar age group.
Moreover, the report should contain a clear explanation about the relevance of the results with reference to the referral question. Finally, a clear overall summary of the results and a conclusion with any recommendations in light of background information and current test data should be included (Flanagan, 2004; Groth-Marnet, 1997; Kaplin, & Saccuzzo, 2005). Conclusion The WAIS-III is a psychometrically sound instrument for assessing intelligence, to help diagnose special population groups, as well as help assess brain damage in individuals 16-89.
The excellent reliability and well validated WAIS scales, as well as vast improvements in the structure, content, procedure, and clinical utility make extraction of more meaningful information more readily available; however, examiner precision and accuracy are required for proper administration and scoring. The many short forms of the WAIS-III are also very useful when there are time or physical constraints; however, they are only recommended as a rough estimate or screening instrument for future assessment.
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