Overview

Over the last 30 years or so, computers have evolved rapidly into powerful and complex systems that underlie virtually every aspect of modern life and, if current trends continue, it is likely that they will be even more pervasive in the future. With the increased embeddedness of computer technology into our society, the characteristics of users have diversified rapidly from a situation where the average user was often a white, middle-aged male with a particular educational and socio-economic background to one in which users of all ages, sexes, social and ethnic backgrounds, levels of education and computer knowledge are interacting with complex interfaces to computer systems. The range and complexity of people's interactions with computers have also grown rapidly over recent years, so that we now do many things via a computer (e.g., managing a bank account, paying household bills, shopping, organising a holiday) that would have been done in the high street just a few years ago.

These rapid developments present significant challenges to interface designers. As the range and sophistication of computer-based tasks have increased so have the interfaces that people are required to use, and so the issue of how people perceive and process complex displays of information when carrying out tasks becomes ever more important. In order to understand these processes more closely, analysts have utilised the theories and methods of cognitive psychology – the study of human perception and information processing – to construct cognitive models: specifications of the mental representations, operations and problem-solving strategies that occur during the execution of computer-based tasks.