Wechsler Memory Scale fourth edition (WMS-IV) i

The Wechsler Memory Scale fourth edition (WMS-IV)

The Wechsler Memory Scale fourth edition (WMS-IV) is a neuropsychological test used to determine an individual's memory functionality level. David Wechsler released the WMS in 1945, which introduced it to the psychological field. However, the tool has undergone considerable changes, giving rise to the present version, which was released in 2009. The test instrument is made up of seven subtests: symbol span, general cognitive screener, design memory, logical memory, and three others (Holdnack, Zhou, Larrabee, Millis, & Salthouse, 2011). Individuals between the ages of 16 and 90 are eligible to take the test.\u00a0 The structure of WMS test has been subjected to numerous studies albeit to determine the reliability and validity of their results. The analytic researches focusing on the previous version of WMS yielded some inconsistent results and were thus not dependable in measuring memory activities. According to Wechsler (2009), the WMS-IV mitigated some of the limitations reported in the previous version. For instance, it is made up of a battery of tests which are specifically designed to evaluate learning, the working memory, the immediate and delayed recall, and recognition of data presented in both verbal and visual modalities. The participants are categorized into two major categories namely: adult battery (16-69) years and older adult battery (65-90) years. The new WMS-IV, an improvement version of the WMS-III has had an excellent reliability and concurrent validity mainly when used with working memory subtest, symbol span, and spatial addition.

Reason for Change: Visual Memory Assessment

One of the main reasons which precipitated the change of WMS-III to WMS-IV was to improve on its assessment of the visual memory. In the third edition, the visual memory was assessed using the family pictures and the faces subtest, an activity which was primarily considered to be unreliable. Even though Milner, Corkin, and Teuber (1968) argued that the face memory was a differentiating factor between the right and the left temporal lobe functioning, the later studies have come to illustrate that the same cannot always be replicated. In fact, the subtest was characterized by a high guessing rate and low level of the correlation to the other visual memory measures. The design subtest was, therefore, developed to limit the confounding cognitive processes. In this scenario, the measurement of the optical images is undertaken within a grid, whereby the participants will be required to recall both the visual as well as the spatial data.

Designing WMS-IV Test

The design of WMS-IV comprises of six sub-tests that are administered to the normative participants for the first time and later repeated after a delay of about 20 to 30 minutes in addition to the optional Brief Cognitive screen. The subtest is scored based on the technical and the interpretive manual and is then arranged with a mean value of 100 and a standard deviation of 15.

Norms

A normative sample for the WMS-IV test is based on the primary data collected, which will then form part of the standardization sample. Stratified sampling is administered to the adult population with ages ranging between 16 and 90 years, and it is done concerning the individual's sex, race, education, and other distinguishing features deemed necessary. Inferential norming are used to produce norms where the information derived from the whole sample dictates the conversion of the raw score to the scaled score as directed by each age band table. The beautiful thing about the test is that it does not raise any issues related to the differences in participant's gender, race, culture, and other social demographics.

Reliability of WMS-IV

Various studies and tests have been undertaken with the main aim of finding the reliability of the WMS-IV memory measuring tool. In one such test, 144 participants were put into six test groups. These groups included those with brain injury (n=30), math disorder (n=22), right temporal lobectomy (n=15), autism (n=22), and schizophrenia (n=55). The ages of the participants were normalized, while the diagnostic criteria were done following WMS-IV technical and interpretive manual. The results obtained in the seven sub-tests showed some internal consistency, thus laying proof of the reliability of the clinical tool (Whipple Drozdick & Munro Cullum, 2011). For instance, the immediate total ranged from 0.83 to 0.9, while the test-retest correlation was shown to be 0.73. WMS-IV provides a reliable measurement of visual memory that is concerned with spatial location. In another study, the internal consistency of spatial addition ranged between 0.89 and 0.93, thereby confirming the suitability of the memory assessment tool.

Validity of WMS-IV

The WMS-IV operates through manuals containing multiple correlation tables which serves to establish the psychometric validity based on some factor analytic studies as well as some other neuropsychological measures. The critical data and referenced benchmarks that mirror the conformity of the test results with the functional outcome are absent. Thus, it is difficult to ascertain the validity of the multiple levels of likelihood ratios could not be calculated (Whipple Drozdick & Munro Cullum, 2011).

The Use and Limitations of WMS-IV

WMS-IV can be used to measure all neuropsychological functions that touch on the seven areas (subsets) that have been identified in the previous sub-section. For instance, clinicians can use the test to assess the level of brain injury and math disorder amongst various normalized samples. However, several limitations impede the success of using the tool (Hoelzle, Nelson, & Smith, 2011). First and foremost, the process of scoring the test is arduous and involving, such that it becomes quite intimidating. Only individuals with adequate training are confident enough to use WMS-IV. Although there is a reduction of time used to examine the normalized sample, it is still not enough to decrease the fatigue level among the participants. Hence, a lower quality of the obtained scores is always registered.

Also, the 20 to 30 minutes delay period between the administrations of the first test and the retest makes it hard to be used with people with aphasia and other forms of disabilities that can cause the test examinee to work slower than usual time. In such instances, the validity of the test will be put into question. Thus, the analysis may not be objective enough, as it depends on the personal weaknesses of the test-taker. This method is inferior to the cardboard grid where an examinee can readily insert a card into the grid at the end of the test period and can be assisted where necessary.

A controversy has been brewing concerning how WMS-IV with the above-mentioned drawbacks could be accepted by the neuropsychological community as an improved version of WMS-III and yet it does not offer any better or adequate method of determining criterion validity. Proponents of the WMS-IV have cited the prevailing ethical standards as the sole motivator for the adoption of the new test (Loring & Bauer, 2010).

References

Hoelzle, J.B., Nelson, N.W., & Smith, C.A. (2011). Comparison of Wechsler Memory Scale-Fourth Edition (WMS–IV) and Third Edition (WMS–III) dimensional structures: Improved ability to evaluate auditory and visual constructs. Journal of Clinical and Experimental Neuropsychology, 33(3), 283-291.

Holdnack, J.A., Zhou, X., Larrabee, G.J., Millis, S.R., & Salthouse, T.A. (2011). Confirmatory factor analysis of the WAIS-IV/WMS-IV. Assessment, 18(2), 178-191.

Loring, D.W., & Bauer, R.M. (2010). Testing the limits: Cautions and concerns regarding the new Wechsler IQ and Memory scales. Neurology, 74(8), 685-690.

Milner, B., Corkin, S., & Teuber, H.-L. (1968). Further analysis of the hippocampal amnesic syndrome: 14-year follow-up study of H.M. Neuropsychology, 6, 215-234.

Wechsler, D. (2009). Wechsler Memory Scale, 4th ed. San Antonio, TX: Pearson.

Whipple Drozdick, L., & Munro Cullum, C. (2011). Expanding the ecological validity of WAIS-IV and WMS-IV with the Texas Functional Living Scale. Assessment, 18(2), 141-155.