Twenty years of research eventually uncovered a number of problems with the original model of STM. STM is not limited to phonemic encoding, as originally thought, and decay and displacement are not the only processes responsible for loss of information.
	These and other findings indicated that STM involves more than a simple rehearsal buffer.
	Alan Baddeley (1986-1992) proposed a more complex model of STM that characterizes it as “working memory," with 4 components.
	The phonological rehearsal loop represented ALL of STM in the original model.  This component is active when one uses recitation to temporarily hold on to information.
	The visuospatial sketchpad allows temporary holding and manipulation of visual images (mentally rearrange the furniture in your bedroom).
	The executive control system controls the deployment of attention, switching the focus of attention and dividing attention as needed. The episodic buffer is a temporary, limited capacity store that allows the various components of working memory to integrate information, and that serves as an interface between working and LTM.