A standard operator in a keystroke-level model (KLM), H represents the act of homing the hands between input devices, such as between the keyboard and the mouse. It was empirically determined to take 400 msec by Card, Moran, and Newell (1980b, 1983).
Early in computing theory, it was established that it was impossible to produce a program that can reliably tell whether any program will eventually halt (rather than run forever). As well as its intrinsic significance, this is typical of a range of impossibility results that establish the fundamental limitations of computation.
a user interface critiquing process carried out by experts with usability guidelines
Important but invisible links between entities in the cognitive dimensions framework. Frequently the links are visible in one direction but not in the other (cell dependencies in spreadsheets, for example). See the text for more details.
Human short term memory
It has been shown that humans' short term memory contain 7 plus or minus 2 units. That is, it is not very big. In addition, short term memory is really short.
situations in which people understand and make requests of a software system, and the system interprets and responds to these requests
imaginary persons with characteristics that are typical of a stakeholder group, developed to serve as actors in analysis and design scenarios