Bridging the Generation Gap: From Work Tasks to User Interface Designs

Abstract Task and model-based design techniques support the design of interactive systems by focusing on the use of integrated modelling notations to support design at vari-ous levels of abstraction. However, they are less concerned with examining the na-ture of the design activities that progress the design from one level of abstraction to another. This paper examines the distinctions between task and model-based approaches. Further, it discusses the role of design activities in such approaches, based on experience with one task-based technique, and the resulting implications for tool support and design guidelines. The discussion is contextualised by exam-ples drawn from a number of case studies where designers applied a task-based approach to solve one particular design problem: that of developing an airline flight query and booking system. Keywords Automatic generation, design guidelines, model-based design, task-based design, task models, Introduction Current interest in task and model-based approaches to design signifies a trend to-wards placing greater emphasis on what an interactive system should do and how people might use it rather than how the system itself works. Designers are encour-aged to conceptualise designs at a higher level of abstraction than is the case when working with standard prototyping tools; in particular, they are encouraged to fo-cus on the behaviour and structure of the user interface rather than on specific de-tails of low-level interaction objects. This interest is reflected in papers presented at the DSV-IS workshops [DSV-IS94, DSV-IS95]. Task and model-based approaches to design have many features in common. Most notably, they both focus on the use of models to represent the various sorts of in-