Abstract
The function of working memory has been studied with the dual task method, in which participants are asked to perform two cognitive tasks concurrently. The resource sharing model of working memory hypothesizes that performances on the two concurrently performed tasks should exhibit a trade-off function. We quantitatively evaluated this hypothesis using the spatial span task (Shah & Miyake, 1996), which consists of two component task requirements: maintaining letter orientations (the storage task) and judging whether the individual letters are normal or mirror-imaged by performing mental rotation (the processing task). The results showed that the performance level for the storage task decreased as the difficulty of the processing task increased, thus supporting the trade-off hypothesis.
