The construct validity of the clinical assessment of working memory ability

Working memory is the cognitive ability to hold a discrete amount of information in mind in an accessible state for utilization in mental tasks. This cognitive ability is impaired in many clinical populations. There have been a number of theoretical shifts in the way that working memory is conceptualized and assessed in the experimental literature. The purpose of this study was to determine whether the Working Memory Indices (and their component subtests) from the WAIS-III and WMS-III accurately assess the working memory construct as it is currently defined in the experimental cognitive literature. Results generally supported the construct validity of the Arithmetic, Digit Span, Letter-Number Sequencing, and Spatial Span subtests as measures of working memory ability. Confirmatory factor analyses revealed that the Wechsler subtests do appear to be measuring the same working memory construct as the experimental cognitive measures used in this study (listening span task, operation span task, and modified lag task), though Arithmetic and Spatial Span had low factor loadings. Additionally, multiple regression analyses revealed that the best predictor models of Wechsler subtests for assessing working memory were composed of the Digit Span, Letter-Number Sequencing, Matrix Reasoning, Vocabulary, Symbol Search, Logical Memory I, and Spatial Span subtests.