Task patterns for taking into account in an efficient and systematic way both standard and erroneous user behaviours

Abstract

While designing interactive software, the use of a formal specification technique is of great help because it provides non-ambiguous, complete and concise notations. The advantages of using such a formalism is widened if it is provided by formal analysis techniques that allow to prove properties about the design, thus giving an early verification to the designer before the application is actually implemented. However, formal specification of interactive systems (even though aiming to produce reliable software) often does not address the issues of erroneous user behaviour. This paper tackles the problem by proposing a systematic way of dealing with erroneous user behaviour. We propose to extend task models (describing standard user behaviour) with erroneous user behaviour. Without appropriate support, incorporating erroneous user behaviour in task models requires much effort from task analysts. We thus propose the definition of patterns of user errors in task models. These patterns of errors are then systematically applied to a task model in order to build a task model covering both standard and erroneous user behaviour. These task models can then be exploited towards system models to provide a systematic way of assessing both system compliance to user tasks and system tolerance to user errors. © 2004 by International Federation for Information Processing. All rights reserved.