Working memory (WM) is a newer theory of short-term memory
(STM), the main differences being the systems by which information is manipulated, and WM's view of STM
as an active system and not just a storehouse for information.
Working memory is made up of three components, the Phonological loop, the Visuo-spatial working memory, and the Central Executive.
The Phonological loop is made up of two parts. First, a phonological store, used to hold the phonological data used to make up words. This is very short-term, and could be compared to a top-down Echoic Memory. Second, the Subvocal rehearsal process used to hold words and sounds that can then be rehearsed. This is where you might recite a telephone number in your head.
The visuo-spatial working memory is a work-pad on which you can 'see' things in your minds eye. This is where you would visualize the Mona Lisa.
The central executive supervises the use of the information stored in the phonological loop, the visuo-spacial working memory, and the long-term memory.
Suggestions for upgrading this theory of short-term memory include possibly adding a musical memory and coming up with a Working long-term memory theory (as opposed to this 'working short-term memory' theory).