An approach to the formal analysis of user complexity

A formal approach to analysing the user complexity of interactive systems or devices is described, based on theoretical results from cognitive psychology. The userʹs knowledge of how to use a system to accomplish the various tasks is represented in a procedural notation that permits quantification of the amount and complexity of the knowledge required and the cognitive processing load involved in using a system. Making a system more usable can be accomplished by altering its design until the knowledge is adequately simplified. By representing the device behaviour formally as well, it is possible to simulate the user-device interaction to obtain rigorous measures of user complexity.