As commonly defined in psychology, working memory (WM) is the ability to maintain and manipulate information in active attention. It includes narrow abilities such as auditory short-term storage, visual-spatial short-term storage, and attentional control. Despite a common definition, working memory is still quite a heterogeneous concept, and it can be measured in many distinct ways. WM was first proposed to be the memory for plans of future action (Miller et al., 1960). Later, the dual-store concept of WM by Alan Baddeley came to dominate cognitive psychology for a long time (Baddeley & Hitch, 1974). In that model, there are two separate domain-specific storage systems: the phonological loop (which stores verbal content) and the visuospatial sketchpad (which stores visuospatial content). And, as in many other models of WM since then, Baddeley’s model proposes a central executive system (or attentional/processing component) that controls the flow of information from and to the two storage systems.