Description
Measures an adult’s intellectual ability
Measures an adult’s intellectual ability
Author:
David Wechsler
Overview:Measure an adult's intellectual ability
Age Range:16-89 years
Completion Time:VIQ, PIQ, and Full Scale IQ in 60-90 minutes
Norms:IQ and Index Scores
Publication Date:1997
Expanded and updated norms, new improved psychometric properties, and updated stimuli are just a few of the many benefits of the newly revised Wechsler Adult Intelligence Scale®—Third Edition (WAIS®–III). Based on one of the most comprehensive standardization samples ever, WAIS–III scales have been co-normed with the new Wechsler Memory Scale®—Third Edition (WMS®–III) to help you examine the important relationship between intellectual functioning and memory.
Expanded, Updated Norms
One of the primary goals of the revision was to develop new norms on a contemporary sample. In addition to being current, the norms also reflect an expanded age range for adults 74 through 89 years of age, reflecting the increased average life expectancy.
Minimal Retraining
The focus was on improvements to the well-known features of this scale rather than on redesign. If you are trained to use WAIS–R®, you will find the transition to WAIS–III easy.
Improved Materials and Content
Item content, artwork, and materials have been improved and updated. Extensive item bias analyses were performed to eliminate biased items. Also, enlarged visual stimuli make the items easier for examinees with decreased visual acuity.
Less Testing Time
Administration time was reduced, and supplementary subtests were added to increase diagnostic utility.
Enhanced Testing for Lower-Functioning Examinees
WAIS–III has extended floors for most subtests, enhancing specificity in testing individuals who have lower cognitive functioning.
Three New Subtests
WAIS–III includes the 11 subtests from WAIS–R and 3 new subtests: Matrix Reasoning, Symbol Search, and Letter-Number Sequencing.
- Matrix Reasoning—A traditional type of nonverbal task where the examinee looks at a picture of geometric shapes and either names or points to the correct answer from five response options.
- Letter-Number Sequencing—A series of orally presented letters and numbers that are presented in a mixed-up order. The examinee must reorder and repeat the list by saying the numbers first in ascending order and then the letters in alphabetical order.
- Symbol Search—A series of paired groups, each pair consisting of a target group and a search group. The examinee indicates, by marking the appropriate box, whether either target symbol appears in the search group.
Validity, Clinical Studies
Validation studies include correlations between WAIS–III and WMS–III, WAIS–R, WISC–III,® WIAT,® Stanford Binet—Fourth Edition, and Raven’s Progressive Matrices. WAIS–III (and WMS–III) clinical group studies included adults with clinical diagnoses of mental retardation, hearing impairments, reading disabilities, math disabilities, attention-deficit disorder, schizophrenia, closed-head injury, chronic alcoholism, Huntington’s chorea, Korsakoff’s syndrome, Parkinson’s disease, and Alzheimer’s disease.
More Information
Call for a free WAIS–III/WMS–II brochure, 999-8982-928-WP299.
Technical Reports
WAIS-III Technical Report: Response to Flynn (PDF – 132 KB)
6-Factor Model
Introduction to the WAIS-III / WMS-III Demographically Adjusted Norms 6-Factor Model Analysis Tool
The 6-Factor Model (Tulsky, Ivnik, Price, & Williams, 2003) is an alternate model for creating composites from WAIS–III / WMS–III subtests. The model is based on the WAIS–III / WMS–III joint factor structure. The subtests used in the 6-Factor configuration of indexes differ from those used in the WAIS–III/WMS–III Scoring Assistant. Researchers must decide which memory index scores are most applicable in their research. See Tulsky et al. (2003) for the rationale and normative tables for these composites.
The six factors and contributing subtests used in this model include:
- Verbal Comprehension
- Vocabulary
- Information
- Similarities
- Perceptual Organization
- Block Design
- Matrix Reasoning
- Picture Completion
- Working Memory
- Letter-Number Sequencing
- Spatial Span
- Processing Speed
- Digit Symbol-Coding
- Symbol Search
- Verbal Memory
- Logical Memory I
- Logical Memory II
- Paired Associates I
- Paired Associates II
- Visual Memory
- Family Pictures I
- Family Pictures II
- Visual Reproduction I
- Visual Reproduction II
The 6-Factor Model substitutes Visual Reproduction for Faces and organizes the memory subtests by sensory domain (auditory and visual), rather than by immediate and delayed conditions. It is not fully clear if this model better reflects the neurological structure of memory or an artifact related to the statistical interdependence of the immediate and delayed memory tasks within each sensory modality. More research of the underlying structure of memory and brain-imaging studies are needed before firm conclusions can be made about the composition of the memory composites.
The demographically adjusted norms are derived from the application of fractional polynomial regression procedures (Royston & Altman, 1994), to the standardization and education/ethnicity over-sample cases from the WAIS–III/WMS–III. The adjusted norms adjust the six WAIS–III/WMS–III Composite Scores for Age (20–89 years), Education Level (7–17 years), Ethnicity (African-American, Hispanic, and Caucasian only) and Sex, for individuals educated primarily in the U.S.
The demographically adjusted scores are most appropriately applied in the context of a neurodiagnostic assessment to minimize the impact of psychosocial variables on the diagnosis of cognitive impairment, such as estimating the degree of cognitive impairment after a brain injury or insult. The demographically adjusted scores are not intended for use in psychoeducational evaluations, determination of intellectual deficiency, vocational assessment, or in any context in which the purpose of the evaluation is to determine the absolute functional level (IQ or Memory) of the examinee relative to a representative sample of the U.S. population. To avoid confusion with traditional IQ and memory scores, the demographically adjusted scores are reported on a T-score metric with a mean of 50 and standard deviation of 10 scaled-score points.
The full demographically adjusted norms are interpreted as:
> 55 = Above Average
45–54 = Average
40–44 = Low Average
35–39 = Mild Impairment
30–34 = Mild to Moderate Impairment
25–29 = Moderate Impairment
20–24 = Moderate to Severe Impairment
< 20 = Severe Impairment
As a clinician, you should be familiar with the research studies and rationale for using demographically adjusted norms. You are responsible for the appropriate use of demographically adjusted norms and should exercise caution when interpreting the adjusted WAIS–III / WMS–III scores.
References
Royston, P. & Altman, D. G. (1994). Regression using fractional polynomials of continuous covariates: Parsimonious parametric modeling. Applied Statistics, 43, 429–467.
Taylor, M. J. & Heaton, R. K. (2001). Sensitivity and specificity of WAIS–III / WMS–III demographically corrected factor scores in neuropsychological assessment. Journal of the International Neuropsychological Society, 7, 867–874.
Tulsky, D. S., Ivnik, R. J., Price, L. R. & Wilkens, C. (2003). Assessment of Cognitive Functioning with the WAIS–III and WMS–III: Development of a Six-Factor Model. In D. S. Tulsky et al., (Eds.) Clinical Interpretation of the WAIS–III and WMS–III. San Diego: Academic Press.
