Cognitive Graphical Walkthrough Interface Evaluation

Abstract

Interface evaluation of a software system is a procedure intended to identify and propose solutions for usability problems caused by the specific software design. The term evaluation generally refers to the process of “gathering data about the usability of a design or product by a specified group of users for a particular activity within a specified environment or work context” (Preece et al., 1994, p. 602). As already stated, the main goal of an interface evaluation is to discover usability problems. A usability problem may be defined as anything that interferes with a user’s ability to efficiently and effectively complete tasks (Karat et al., 1992). The most applied interface evaluation methodologies are the expert-based and the empirical (user-based) evaluations. Expert evaluation is a relatively cheap and efficient formative evaluation method applied even on system prototypes or design specifications up to the almost-ready-to-ship product. The main idea is to present the tasks supported by the interface to an interdisciplinary group of experts, who will take the part of would-be users and try to identify possible deficiencies in the interface design. According to Reeves (1993), expert-based evaluations are perhaps the most applied evaluation strategy. They provide a crucial advantage that makes them more affordable compared to the empirical ones; in general, it is easier and cheaper to find experts rather than users who are eager to perform the evaluation. The main idea is that experts from different cognitive domains (at least one from the domain of HCI and one from the cognitive domain under evaluation) are asked to judge the interface, everyone from his or her own point of view. It is important that they all are experienced, so they can see the interface through the eyes of the user and reveal problems and deficiencies of the interface. One strong advantage of the methods is that they can be applied very early in the design cycle, even on paper mock-ups. The expert’s expertise allows the expert to understand the functionality of the system under construction, even if the expert lacks the whole picture of the product. A first look at the basic characteristics would be sufficient for an expert. On the other hand, user-based evaluations can be applied only after the product has reached a certain level of completion.