Visual query systems (VQSs) are query systems for databases that use visual representations to depict the domain of interest and express related requests. VQSs can be seen as an evolution of query languages adopted into database management systems; they are designed to improve the effectiveness of the human-computer communication. Thus, their most important features are those that determine the nature of the human-computer dialogue. In order to survey and compare existing VQSs used for querying traditional databases, we first introduce a classification based on such features, namely the adopted visual representations and the interaction strategies. We then identify several user types and match the VQS classes against them, in order to understand which kind of system may be suitable for each kind of user. We also report usability experiments which support our claims. Finally, some of the most important open problems in the VQS area are described. 1.

Different approaches to the measurement of usability are reviewed and related to definitions of usability in international standards. It is concluded that reliable measures of overall usability can only be obtained by assessing the effectiveness, efficiency and satisfaction with which representative users carry out representative tasks in representative environments. This requires a detailed understanding of the context of use of a product. The ESPRIT MUSiC project has developed tools which can be used to measure usability in the laboratory and the field. An overview is given of the methods and tools for measuring user performance, cognitive workload and user perceived quality. Contents 1. Benefits of improved usability............................................................................................................................ 1 1.1. Usability evaluation and system development................................................................................ 1 2. Usability features and attributes....................................................................................................................... 2 2.1. Can usability be measured in terms of features and attributes?................................................... 2

Online spaces that enable shared public interpersonal communications are of significant social, organizational, and economic importance. In this paper, a theoretical model and associated unobtrusive method are proposed for researching the relationship between online spaces and the behavior they host. The model focuses on the collective impact that individual information-overload coping strategies have on the dynamics of open, interactive public online group discourse. Empirical research was undertaken to assess the validity of both the method and the model, based on the analysis of over 2.65 million postings to 600 Usenet newsgroups over a 6-month period. Our findings support the assertion that individual strategies for coping with “information overload” have an observable impact on large-scale online group discourse. Evidence was found for the hypotheses that: (1) users are more likely to respond to simpler messages in overloaded mass interaction; (2) users are more likely to end active participation as the overloading of mass interaction increases; and (3) users are more likely to generate simpler responses as the overloading of mass interaction grows. The theoretical model outlined offers insight into aspects of computer-mediated communication tool usability, technology design, and provides a road map for future empirical research.

The large-scale adoption of computer mediated communication technologies has resulted in what has been described as “mass interaction”, shared discourse between hundreds, thousands or more individuals. A number of theoretical papers have made the argument that because of the existence of various technological and psychological constraints, the forms that mass interaction takes, can, partly be understood in terms of system dynamics. In particular, it has been suggested that user information overload results in non-linear feedback loops which impacts on discourse structure. This paper describes an empirical examination of three hypothesized effects of such loops by the analysis of 2.65 million USENET messages posted to 600 newsgroups over a 6-month period. Statistical analysis of the data demonstrated the existence of the hypothesized effects and support the assertion that individual ‘information overload ’ coping strategies have an observable impact on mass interaction discourse dynamics. This in turn suggests that the usability of computer mediated communication technologies can be examined in terms of group-level usability.

This paper is about database researchers building interactive information systems. It tells the reader of their initial enthusiasm and user-induced frustration, the consequent discovery of both human-computer interaction (hci) world and the concept of system "usability", and finally their quite successful coupling of hci and databases. Key words: User Interface, Information System, Usability 1. INTRODUCTION It is now generally accepted that factors which mainly influence the success of computerized projects are human and organizational, rather than technological. The mere fact of using computer technologies, even if they are reliable, powerful and innovative, cannot solve work organization problems if the acquired instruments are not in harmony with the attitudes, motivations and competencies of workers in that organization, and also with the social and environmental context of their activities.

The need of friendly environments for effective information access is further enforced by the growth of the global Internet, which is causing a dramatic change in both the kind of people who access the information and the types of information itself (ranging from unstructured multimedia data to traditional record-oriented data). To cope with these new demands, the interaction techniques traditionally offered to the users have to evolve and eventually integrate in a powerful interface to the global information infrastructure. The new interaction mechanisms must be especially friendly and easy-to-use, since, given the enormous quantity of information sources available on the Internet, most of the users remain "permanent novices" with respect to each one of the sources they have access to. This tutorial offers a survey of the main approaches adopted for letting the users effectively interact with the Web. Thus, it covers topics related with both extracting the information of interest spre...

The large-scale adoption of computer mediated communication technologies has resulted in what has been described as “mass interaction”, shared discourse between hundreds, thousands or more individuals. The emergence of mass interaction presents new opportunities to learn about and understand human communication, and information technologies. A number of theoretical papers suggest that the forms that mass interaction takes, can, partly be understood in terms of resource constraints. In particular, it has been suggested that user information overload results in non-linear feedback loops which impacts on discourse structure. Further, that the nature of these feedback loops is related to technology type. This paper describes an empirical examination of three hypothesized effects of such loops by the analysis of 2.65 million USENET messages posted to 600 newsgroups over a 6-month period. This represents the first empirical exploration of the impact of systems effects on Usenet discourse. The paper then examines the relationship between the hypothesized non-linear feedback loops and technology type by comparing the Usenet data with that of 478,240 email messages sent to 487 email lists managed by Listserv software over a 5-month period.