Textbook of Usability

b. 1951, USA · Curators' Professor at the University of Missouri

Also known as: Nelson Cowan

Nelson Cowan is the leading contemporary authority on working memory. His 2001 paper The Magical Number 4 in Short-Term Memory: A Reconsideration of Mental Storage Capacity gathered evidence from tasks that controlled for chunking, rehearsal and long-term memory contributions, and concluded that the true capacity of attentive working memory is closer to four chunks than to George Miller's seven.

The result is now the standard estimate cited in cognitive psychology, and is the working-memory limit that interface designers should plan around when arranging menu groups, dashboard tiles, and multi-step task flows. Cowan's later work on developmental change in working memory has further refined the figure for children, older adults, and clinical populations.