David Alonso-Ríos

Usability: A Critical Analysis and a Taxonomy

A major obstacle to the implantation of User-Centered Design in the real world is the fact that no precise definition of the concept of usability exists that is widely accepted and applied in practice. Generally speaking, the literature tends to define usability in overly brief and ambiguous terms and to describe its application in informal terms. This is one of the main reasons why ad hoc techniques predominate in usability study methodologies. The aims of this article are to investigate the concept of usability and to describe it by means of a detailed taxonomy that is organized hierarchically and that contains exhaustive descriptions of usability attributes. This taxonomy can be used to support different stages in the development of usable systems.

A Context-of-Use Taxonomy for Usability Studies

The interest in developing usable products has led to the inclusion of usability aspects in product development processes. Nonetheless, the fact that there is a tendency to overlook characteristics of the context in which a product is to be used means that the usability of a product in its operational environment is often diminished. One of the main reasons why this is the case is because there is no clear and sufficiently detailed model available for defining the concept of context of use. A comprehensive taxonomy that describes context of use and its attributes by means of precise definitions is proposed. This taxonomy will serve as a basis for improving the validity of usability activities by enabling an analysis of the conditions of use of a product in usability studies in a structured way.

A Snort-based agent for a JADE multi-agent intrusion detection system

We describe the design of a misuse detection agent, one of the distinct agents in a multi-agent-based intrusion detection system. This system is being implemented in JADE, a well-known multi-agent platform based in Java. The agent analyses the packets in the network connections using a packet sniffer and then creates a data model based on the information obtained. This data model is the input to a rule-based inference engine agent, which uses the Rete algorithm for pattern matching and the rules of the signature-based intrusion detection system, Snort. Specifically, an implementation in Java language – the Drools-JBoss Rules – was used and a parser was implemented that converts Snort rules into Drools rules. The use of object-oriented techniques, together with design patterns, means that the agent is flexible, easily configurable and extensible.

A User Study with GUIs Tailored for Smartphones

Web-based graphical user interfaces (GUIs) are mostly not tailored for small devices with touchscreens, such as smartphones. There is little scientific evidence on the conditions where additional taps for navigation are better or scrolling. Therefore, we conducted a user study in which we evaluated different ways of tailoring a GUI for a smartphone. Each participant performed the same task with two different layouts of the same GUI. We collected quantitative data through measuring task completion time and error rates, as well as qualitative data through subjective questionnaires. The main result is that minimizing the number of taps is important on a smartphone. Users performed significantly better when they could scroll (vertically), instead of tapping on widget elements (tabs). This preference was also reflected in their subjective opinions.

A Taxonomy-Based Usability Study of an Intelligent Speed Adaptation Device

Usability studies are often based on ad hoc definitions of usability. These studies can be difficult to generalize, they might have a steep learning curve, and there is always the danger of being inconsistent with the concept of usability as defined in standards and the literature. This alternative approach involves comprehensive, general-purpose, and hierarchically structured taxonomies that follow closely the main usability literature. These taxonomies are then instantiated for a specific product. To illustrate this approach, a usability study for a prototype of an Intelligent Speed Adaptation device is described. The usability study consists of usability requirements analysis, heuristic evaluation, and subjective analysis, which helped identify problems of clarity, operability, robustness, safety, and aesthetics. As a context-specific usability taxonomy for this particular field of application happened to exist, the way that real-world usability results can be mapped to that taxonomy compared to the taxonomy in this article is examined, with the argument that this study’s taxonomy is more complete and generalizable.

An HTML analyzer for the study of web usability

This paper presents an HTML analyzer for the study of Web usability. The analyzer parses HTML code in order to extract usability information from Web pages. For usability aspects that can be analyzed automatically, the analyzer draws conclusions and offers suggestions. For more subjective usability issues, it assists the expert by presenting relevant information in a convenient way. Many similar applications exist, but they mostly focus on well-known usability problems and pay little attention to subtler aspects. More alarmingly, they suffer from basic usability problems. Our results show that our analyzer examines several usability aspects - related to ease of navigation, understandability, flexibility, and compatibility - that are generally ignored by the other tools.

A Multi-agent System Based on Evolutionary Learning for the Usability Analysis of Websites

In this chapter we propose a novel multi-agent system for the semi-automated study of the usability of websites, an increasingly critical issue given the ubiquity of the Web and its technological evolution. The proposed system constructs a key phrase-based model of the users trying to reach one URL from another, simulates the browsing process, and analyses the web pages in the path. The resulting usability analysis is focused on issues such as navigation paths, links, page content, HTML coding, and accessibility. Our system automatically draws usability conclusions and suggestions and also presents significant data in support of the human usability expert. The architecture of the system consists of rule-based reactive agents subject to evolutionary processes. The application of evolution allows the agents to explore possible solutions in a more realistic way than either exhaustive or arbitrary examinations.

A user study on tailoring GUIs for smartphones

Usually, Web-based graphical user interfaces (GUIs) are not specifically tailored for different devices with touchscreens, such as smartphones, where interaction is affected mainly by screen size. There is little scientific evidence on the benefits of tailoring in general, and in particular on the conditions where scrolling is good or bad. Therefore, we conducted a user study in which we experimentally evaluated a GUI tailored for a smartphone and another non-tailored one. The tailoring in this case only rearranges widgets in a way that the width of the device screen is sufficient but vertical scrolling may be necessary. Each participant performed the same task with these two different layouts. We collected quantitative data through measuring task completion time and error rates, as well as qualitative data through subjective questionnaires and interviews. The main result is that tailoring a GUI for a smartphone is important, since task performance time was significantly shorter when using a tailored GUI requiring only vertical scrolling as compared to a non-tailored one. This preference was also reflected in the subjective opinions of the users.

A User Study with GUIs Tailored for Smartphones and Tablet PCs

Usually, Web-based graphical user interfaces (GUIs) are not specifically tailored for different devices with touch-screens, such as smartphones and tablet PCs, where interaction is affected mainly by screen size. There is little scientific evidence on the conditions under which additional taps for navigation are better than scrolling or vice versa. Therefore, we conducted a user study in which we experimentally evaluated GUIs tailored for a smartphone and a tablet PC, respectively. Each participant performed the same task with two different layouts of the same GUI, either on a given smartphone or tablet PC. We collected quantitative data through measuring task completion time and error rates, as well as qualitative data through subjective questionnaires. The main result is that tailoring a GUI specifically for a smartphone or tablet PC, respectively, is important, since screen size matters. Users performed significantly better when they could use the tailored version on the given device. This preference was also reflected in their subjective opinions.

Usability evaluation and development of heuristics for second-screen applications

This paper describes a methodological approach for the usability evaluation of a second-screen application, that is, the use of the same application in two devices simultaneously, one of them taking a more passive role acting as a second screen. In our case, the devices are a tablet and a smart TV, and the application is a sports news application that provides news and multimedia content. We perform the usability analysis of the application following some comprehensive taxonomies of usability and context-of-use attributes. We put the focus of the analysis on the interaction between the two devices because it is the most challenging part and is a new form of use that is becoming more common nowadays. After this analysis we generalize some usability heuristics that can be useful for assessing second-screen applications.