Improving digit span assessment of short-term verbal memory

Abstract

We measured digit span (DS) in two experiments that used computerized presentation of randomized auditory digits with performance-adapted list length adjustment. A new mean span (MS) metric of DS was developed that showed reduced variance, improved test–retest reliability, and higher correlations with the results of other neuropsychological test results when compared to traditional DS measures. The MS metric also enhanced the sensitivity of forward versus backward span comparisons, enabled the development of normative performance criteria with subdigit precision, and elucidated changes in DS performance with age and education level. Computerized stimulus delivery and improved scoring metrics significantly enhance the precision of DS assessments of short-term verbal memory.

Keywords:

• Digit span
• Metrics
• Computer
• Aging
• Education
• Executive function
• Attention
• Verbal memory
• Auditory

Supported by grants from the Office of Research and Development, Rehabilitation R&D Service, Department of Veterans Affairs and by National Institutes of Health (NIH) Grant ES014038. The content is solely the responsibility of the authors and does not necessarily represent the official views of the funding agencies.

Notes

¹The CCAB includes the following computerized tests and questionnaires: finger tapping, simple reaction time, symbol–digit, Stroop, digit span forward and backward, phonemic and semantic verbal fluency, card sorting, verbal list learning, spatial span, trail making, symmetry detection, design fluency, the Wechsler Test of Adult Reading (WTAR), visual feature conjunction, the Paced Auditory Serial Addition Task (PASAT), the Cognitive Failures Questionnaire (CFQ), the posttraumatic stress disorder (PTSD) symptoms checklist, and a traumatic brain injury (TBI) questionnaire.