CAPACITY LIMITATIONS OF A CLASSIC M-POWER MEASURE - A MODIFIED DUAL-TASK APPROACH

A modified dual-task approach was employed with 7- to 9-year-olds in a n effort to determine whether one of the classic M-power measures, the digit placement task, is indeed capacity-limited. To this end, a comp uterized version of a three-item digit placement task was administered in addition to three other computerized tasks: a four-item digit plac ement task, simple reaction time (RT) to a tone presented alone, and r eaction time to a tone occurring during the performance of another thr ee-item digit placement task. Careful examination of the data revealed that several critical assumptions concerning the use of the dual-task procedure were successfully met. This permitted a test of the extent to which dual-task RTs were predictive of accuracy in the harder, four -item digit placement task. Not only was this relationship significant , but after partialling out other possible sources of variance, a sign ificant correlation remained,indicating that the digit placement task is indeed capacity-limited. (C) 1997 Academic Press.