The document discusses the history and development of the working memory model. It begins by introducing Michael Long's interaction hypothesis from 1983 which proposed that comprehensible input alone is not sufficient for second language acquisition and that interaction is also important. It then provides a brief overview of the evolution of models of short-term and working memory, from William James' distinction between primary and secondary memory, to the Atkinson-Shiffrin model and the influential Baddeley-Hitch model from 1974 which proposed the multi-component working memory system consisting of the central executive, phonological loop, and visuospatial sketchpad.