In this chapter, the authors provide a review of the general method used in the experiments prior to a more detailed discussion of the various experiments conducted to test our theoretical framework. Because complex skilled performance seems so closely related to dualor multiple-task situations (which are also related to attention switching) we now turn to aging and dual-task performance. The authors discuss unanswered general attention issues which must be addressed for a complete understanding of complex multiple-task performance in general, which may lead to a better understanding of age-related multiple-task performance. The chapter describes principles of training for young adults, previously-acquired automatic processes, stroop interference effects, lexical decisions and development of new automatic processes. The present framework, focusing on an intact associative-learning mechanism and an age-related disruption in the priority-learning mechanism, leads to specific predictions concerning age-related performance in CM memory, visual-, and hybrid memory/visual-search tasks. The concept of working memory is central to many models of skill acquisition.