WAIS-IV and MMPI-2: Development, Reliability, and Use

WAIS-IV Test Development

The Wechsler Adult Intelligence Scale–Fourth Edition (WAIS-IV) was developed to offer the most advanced measure of cognitive ability in response to an ever-changing clinical landscape (Valentine et al., 2020). It is considered the "gold standard" in cognitive assessment, measuring the cognitive ability of adults and older adolescents. The test aids in examining the relationship between intellectual functioning and memory.

The WAIS-IV is a revision of the WAIS-III, and that revision was necessitated by the cultural and demographic changes that have taken place in the general population. The WAIS-III was developed in 1997, and since then there have been considerable changes in population age and improvements in the standard of living. Society has become more diverse, making it necessary to revise the test. There has also been an increase in caseloads involving older adults, and the WAIS-IV is designed to be developmentally appropriate for this group (Drozdick et al., 2018).

Reliability and Validity of the WAIS-IV

The reliability of the WAIS-IV is well established, and the test demonstrates high consistency. During development, the test's creators yielded a large number of reliable and valid scores. Test-retest reliabilities of the WAIS-IV ranged from 0.70 to 0.90 over a two-to-twelve-week period (Valentine et al., 2020). Inter-scorer coefficients were all above 0.90. The central reliability figure for the standardization sample demonstrated good internal consistency, with a Full-Scale IQ (FSIQ) reliability of 0.98.

Reliability reflects consistency of test results, which can be verified using alternate forms of the test. The WAIS-IV correlates highly with the Stanford-Binet IV, establishing the validity of the instrument. Numerous researchers have explored both four-factor and five-factor structural models of the WAIS-IV and concluded that both offered a good fit, further confirming its validity (Valentine et al., 2020).

WAIS-IV Ethical Considerations, Normed Reference Group, and Clinical Use

To ensure no alterations in test scores, the WAIS-IV includes a practical scoring assistant and report-writer software that generates concise score reports. Using these tools, the test administrator can remain ethical and accurate when administering and scoring the test. It is vital to ensure that test scores are not compromised, that the testing process is fair, and that cheating is avoided. The developers have provided tools to safeguard the scores of each participant. The examiner enters raw scores using the scoring assistant, and the software generates concise reports. The test has also been shortened to reduce administration time, a decision driven by the increased caseloads faced by clinicians.

The WAIS-IV was standardized on a normative sample of 2,200 participants ranging in age from 16 to 90 years (Valentine et al., 2020). All participants were residents of the United States. The sample was designed to match the U.S. population based on age, sex, geographic location, education level, and race/ethnicity. The sample comprised 200 examinees for each age band from 16 to 69, and 100 examinees for each age band from 70 to 90. Co-norming with the Wechsler Memory Scale–Fourth Edition (WMS-IV) occurred as it had in previous editions, specifically when research programs overlapped during standardization.

The age range was widened to reflect the reality that people are living longer, and the test was revised to meet the changing demographics reflected in national census data. The number of core subtests was reduced from 13 to 10 to accommodate the limited time typically available for clinical assessments.

The WAIS-IV evaluates intellectual performance as a multidimensional construct. There are numerous scales that assess different types of intellectual functioning. The test not only provides IQ scores but also offers vital information regarding an examinee's strengths and areas of difficulty (Drozdick et al., 2018). There are ten core subtests and five additional optional subtests (Abdelhamid et al., 2021). All scores are summed into four indexes: the Verbal Comprehension Index (VCI), the Perceptual Reasoning Index (PRI), the Working Memory Index (WMI), and the Processing Speed Index (PSI).

The WAIS-IV yields two broad scores summarizing general intellectual ability: the Full-Scale IQ (FSIQ) and the General Ability Index (GAI). The FSIQ is derived from the combined performance across all four indexes, while the GAI is derived from the six subtests comprising the VCI and PRI.

MMPI-2 Test Development

The Minnesota Multiphasic Personality Inventory-2 (MMPI-2) was developed to assist with routine psychiatric casework for adult patients by helping clinicians determine the severity of their conditions. Prior to the development of the test, adult patients were asked to complete a self-report personality inventory that was considered too transparent and susceptible to manipulation by the test taker. Because the self-report could not reliably indicate severity—since the respondent could falsify or manipulate their answers—revision became necessary (Giromini et al., 2019).

Given the test's widespread use, a revision was needed to make it more representative of the United States population. This desire to update the instrument gave rise to the MMPI-2. Outdated or offensive items involving sexual and religious content were also removed or revised. The MMPI-2 measures psychological and behavioral dysfunction associated with mental illness. Mental health professionals and psychologists use it to assist in developing treatment plans, answering legal questions in forensic psychology, supporting differential diagnoses, screening job candidates, and conducting therapeutic assessments.

References

Abdelhamid, G. S. M., Bassiouni, M. G. A., & Gómez-Benito, J. (2021). Assessing cognitive abilities using the WAIS-IV: An item response theory approach. International Journal of Environmental Research and Public Health, 18(13), 6835.

Drozdick, L. W., Raiford, S. E., Wahlstrom, D., & Weiss, L. G. (2018). The Wechsler Adult Intelligence Scale—Fourth Edition and the Wechsler Memory Scale—Fourth Edition.

Giromini, L., Lettieri, S. C., Zizolfi, S., Zizolfi, D., Viglione, D. J., Brusadelli, E., Perfetti, B., di Carlo, D. A., & Zennaro, A. (2019). Beyond rare-symptoms endorsement: A clinical comparison simulation study using the Minnesota Multiphasic Personality Inventory-2 (MMPI-2) with the Inventory of Problems-29 (IOP-29). Psychological Injury and Law, 12(3), 212–224. https://doi.org/10.1007/s12207-019-09357-7

Sellbom, M. (2019). The MMPI-2-Restructured Form (MMPI-2-RF): Assessment of personality and psychopathology in the twenty-first century. Annual Review of Clinical Psychology, 15(1), 149–177.

Valentine, T., Block, C., Eversole, K., Boxley, L., & Dawson, E. (2020). Wechsler Adult Intelligence Scale–IV (WAIS–IV). The Wiley Encyclopedia of Personality and Individual Differences: Measurement and Assessment, 457–463.