Trade-off decision making in user interface design

The way in which designers choose between alternatives in user interface design can affect both the design process and also the quality of the outcome, i.e., the user interface. However, little is known about the knowledge drawn on during, or the processes that guide, the choice between design alternatives. This paper presents the results of an empirical study aimed at modelling 'trade-off decision making' in user interface design. It is argued that a single abstract vocabulary can capture important aspects of the rich knowledge drawn on during design problem solving. It is also argued that designers' reasoning during 'choice episodes' is not sophisticated. In choosing between alternatives in design, designers invariably limit the range, or nature, of the alternatives considered. The implications of this finding are discussed.