CHAPTER 62: WECHSLER MEMORY SCALE—FOURTH EDITION (WMS-IV)

Description

The Wechsler Memory Scale—Fourth Edition (WMS-IV), first introduced by Wechsler (1945), is a standardized measure of visual, auditory, and working memory in adults ages 16 to 69 years old and older adults ages 65 to 90 years old, and is designed to assess memory deficits in a variety of patient populations, such as those with neurological and psychiatric disorders (Chittooran, 2012). Theoretical underpinnings of the battery include visual memory encompassing the Designs II and Visual Reproduction II subtests, visual working memory covering the Symbol Span and Spatial Addition subtests, and auditory memory, which includes Logical Memory II and Verbal Paired Associates II subtests, as well as a two-factor model consisting of visual (Designs II, Visual Reproduction II, Spatial Addition, and Symbol Span subtests) and auditory (Logical Memory II and Verbal Paired Associates II subtests) (Hoelzle, Nelson, & Smith, 2011). The Adult Battery includes six primary subtests and an optional Brief Cognitive Status Exam, whereas the Older Adult Battery only includes four primary subtests as well as the optional Brief Cognitive Status Exam. The WMS-IV could be considered a complex assessment where each individual subtest can take up to 30 minutes to complete with total administration times ranging from 130 to 190 minutes. Although time consuming, its results can generate unique insights into client ability (Chittooran, 2012). The WMS-IV generates 5 individual index scores, 12 primary subtest scores, 9 secondary subtest scores, and 13 contrast scores where raw scores as well as age-adjusted scaled scores can be evaluated for use as predictor variables in primary logistic regressions (Miller, 2010).

Psychometrics

Data from normative samples across several age groups for Spatial Addition (n = 900) and Symbol Span (n=1400) subtests established robust internal consistency where Spatial Addition scores ranged from α = 0.89 to 0.93 and Symbol Span ranged from 0.76 to 0.92 (Holdnack & Drozdick, n.d). Test-retest reliabilities were r = 0.77 for Spatial Addition and 0.72 for Symbol Span, whereas concurrent validity found that Spatial Addition and Symbol Span correlated at 0.58 and 0.52 with WMS-III Spatial Span, respectively suggesting that the newer fourth edition is indeed different (Holdnack & Drozdick n.d). Data from clinical samples also collected as part of standardization of the WMS-IV included traumatic brain injury (n = 30), right temporal lobectomy (n = 15), math disorder (n = 22), schizophrenia (n = 55), and autism (n = 22); obtained measures of internal consistency for the subtests of Immediate Total at α = 0.83 to 0.90), Immediate Content (0.66 to 0.88), Immediate Spatial (0.70 to 83), Delayed Total (0.80 to 0.90), Delayed Content (0.70 to 0.84), and Delayed Spatial (0.67 to 0.82); whereas test-retest reliabilities were Immediate Total (r = 0.73), Immediate Content (0.64), Immediate Spatial (0.50), Delayed Total (0.72), Delayed Content (0.64), and Delayed Spatial (.50) (Holdnack & Drozdick, n.d). The study also found that the Designs Total Immediate section correlated at 0.38 with the Immediate Memory section of the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and Designs Delayed correlated at (0.44) with RBANS Delayed Memory (Holdnack & Drozdick, n.d). Finally, a factor analysis by Hoelzle et al. (2011) found that a robust two-dimensional WMS–IV structure was supported across age-based normative samples that emphasized moderately correlated dimensions of (a) auditory learning/memory and (b) visual attention/memory. The auditory learning/memory dimension reflected Logical Memory and Verbal Paired Associates subtests, whereas the Designs subtests were primarily reflected on visual attention/memory dimensions.

Advantages

There is a significant amount of research in support of previous editions on which the WSM-IV is based. The battery is available from Pearson Clinical, where further information regarding the most recent and previous versions can be found. Finally, established norms for the WMS-IV are based on large clinical samples.

Disadvantages

The amount of direct evidence pertaining to the latest WMS-IV is limited. It is also a complex assessment to administer and score and training may be required. The basic kit is roughly $800, making it rather expensive to use in private practice, and as administration time can be long as well, in certain settings that demand the delivery of expedient occupational therapy services, the WMS-IV may not be practical.

Administration

The examination manual includes complete standardized instructions as well as scoring procedures where during assessment, the quality of responses and the patterns of success and failures, along with the individual scores are considered during the evaluation process (Sattler & Ryan, 2009).

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