MIS–A new scoring method for the operation span task that accounts for Math, remembered Items and Sequence

The operation span task is a well-validated measure of the executive component of working memory. Previous scoring systems of this task focus predominantly on the span part of the task, while the distractor–math task–serves as an exclusion criterion for test assessment only. Here, we propose a new Math-Item-Sequence (MIS) system to score performance on the Ospan based on both the span and math part. This new system provides three main improvements: 1) it eliminates the need to introduce arbitrary exclusion thresholds based on performance on the distractor task; 2) it takes into account remembered letters, and their relative position in the sequence separately; 3) it considers performance on the math task in the scoring of the Ospan task as a downweighing factor. In 6 independent samples we show that MIS score correlates highly with previously recommended scoring methods, suggesting that it measures the same underlying concepts. We also show that internal consistency of MIS is very good and comparable to or higher than the previous methods. We argue that MIS could be used in all samples, but might be of particular interest for small samples, where exclusions of participants are especially costly.