 Working memory is a cognitive system with a limited capacity that is responsible for temporarily holding information available for processing. Working memory is important for reasoning and the guidance of decision-making and behavior. Working memory is often used synonymously with short-term memory, but some theorists consider the two forms of memory distinct, assuming that working memory allows for the manipulation of stored information, whereas short-term memory only refers to the short-term storage of information. Working memory is a theoretical concept central to cognitive psychology, neuropsychology, and neuroscience. In 1974, Batley and Hitch introduced a multi-component model of working memory. The theory proposed a model containing three components, the central executive, the phonological loop, and the visual spatial sketch pad with the central executive functioning as a control center of sorts, directing info between the phonological and visual spatial components. The central executive is responsible interavial for directing the attention to relevant information, suppressing irrelevant information and inappropriate actions, and coordinating cognitive processes when more than one task is simultaneously performed. A central executive is responsible for supervising the integration of information and for coordinating slave systems that are responsible for the short-term maintenance of information. One slave system, the phonological loop plural stores phonological information that is, the sound of language and prevents its decay by continuously refreshing it in a reversal loop. It can, for example, maintain a 7-digit telephone number for as long as one repeats the number to oneself again and again. The other slave system, the visual spatial sketch pad, stores visual and spatial information. It can be used, for example, for constructing and manipulating visual images and for representing mental maps. The sketch pad can be further broken down into a visual subsystem dealing with such phenomena as shape, color, and texture and a spatial subsystem dealing with location. In 2000, BABAE extended the model by adding the fourth component, the episodic buffer, which holds representations that integrate phonological, visual, and spatial information, and possibly information not covered by the slave systems e.g., semantic information, musical information. The episodic buffer is also the link between working memory and long-term memory. The component is episodic because it is assumed to bind information into a unitary episodic representation. The episodic buffer resembles Tuddling's concept of episodic memory, but it differs in that the episodic buffer is a temporary store.