Digit Ordering Test: Clinical, psychometric, and experimental evaluation of a verbal working memory test

Cooper, Sagar, Jordan, Harvey, and Sullivan (1991) proposed a Digit Orderin g Test (DOT) for the assessment of verbal working memory: A series of seven digits has to be memorized and immediately recalled in ascending order. In several studies Cooper and co-workers showed selectively reduced DOT perfo rmance in patients with Parkinson's disease (PD). We present results from t hree studies on the properties of this test. In study 1 we replicated the o riginal findings and evaluated a new scoring method. Study 2 addressed the psychometric features of the DOT and provides normative data based on a tot al of 134 test protocols (PD: 18, other neurological patients: 60, healthy controls: 56). In study 3 we used an experimental modification of the test (DOT-EXP) to evaluate the effects of the presentation rate on serial recall and digit ordering performance. The standard presentation rate of seven di gits in 5 s was confirmed as most sensitive for detection of verbal working memory deficits. Findings confirmed that the DOT addresses the manipulator y component of verbal working memory and conveniently detects respective de ficits in clinical testing.