Atkinson’s and Shiffrin’s (1968) multi-store model was extremely successful in terms of the amount of research it generated. However, as a result of this research, it became apparent that there were a number of problems with their ideas concerning the characteristics of short-term memory.
Building on this research, Baddeley and Hitch (1974) developed an alternative model of short-term memory which they called working memory.
There are three main components to the original 1974 version of the working memory model. These are the central executive which acts like a conductor or manager allocating processing resources and coordinating the activity of the two slave systems, the phonological loop and the visuo-spatial sketch pad. The phonological loop is the inner ear and inner voice and is responsible for processing phonological information. The visuo-spatial sketch pad is the inner eye and processes visual and spatial information. Having separate slave systems explains how people are able to perform two tasks at the same time (one visuo-spatial and one phonological), and accounts for patients such as KF who have a reduced digit span (damage to the phonological loop) but normal visual short term memory. In 2000 the episodic buffer was added, this is a temporary storage system that allows information from the subsidiary systems to be combined with information from the LTM.
The Central Executive is the most important component in the model and is responsible for monitoring and coordinating the operation for the subsidiary systems. It is flexible in that it can process information from any modality and also has some storage capacity, though extremely limited. It has a major role in attention, planning and synthesising information, not only from the slave systems but also from the LTM.
The Phonological loop stores a limited amount of sounds for brief periods and can be thought of as an inner ear. It is thought to consist of two components. One