Silvia Gabrielli

Visualizing locations of off-screen objects on mobile devices: a comparative evaluation of three approaches

Browsing large information spaces such as maps on the limited screen of mobile devices often requires people to perform panning and zooming operations that move relevant display content off-screen. This makes it difficult to perform spatial tasks such as finding the location of Points Of Interest (POIs) in a city. Visualizing the location of off-screen objects can mitigate this problem: in this paper, we present a user study comparing the Halo [2] approach with two other techniques based on arrows. Halo surrounds off-screen objects with circles that reach the display window, so that users can derive the location and distance of objects by observing the visible portion of the corresponding circles. In the two arrow-based techniques, arrows point at objects and their size and body length, respectively, inform about the distance of objects. Our study involved four tasks requiring users to identify and compare off-screen objects locations, and also investigated the effectiveness of the three techniques with respect to the number of off-screen objects. Arrows allowed users to order off-screen objects faster and more accurately according to their distance, while Halo allowed users to better identify the correct location of off-screen objects. Implications of these results for mobile map-based applications are also discussed.

Appropriating and assessing heuristics for mobile computing

Mobile computing presents formidable challenges not only to the design of applications but also to each and every phase of the systems lifecycle. In particular, the HCI community is still struggling with the challenges that mobile computing poses to evaluation. Expert-based evaluation techniques are well known and they do enable a relatively quick and easy evaluation. Heuristic evaluation, in particular, has been widely applied and investigated, most likely due to its efficiency in detecting most of usability flaws at front of a rather limited investment of time and human resources in the evaluation. However, the capacity of expert-based techniques to capture contextual factors in mobile computing is a major concern. In this paper, we report an effort for realizing usability heuristics appropriate for mobile computing. The effort intends to capture contextual requirements while still drawing from the inexpensive and flexible nature of heuristic-based techniques. This work has been carried out in the context of a research project task geared toward developing a heuristic-based evaluation methodology for mobile computing. This paper describes the methodology that we adopted toward realizing mobile heuristics. It also reports a study that we carried out in order to assess the relevance of the realized mobile heuristics by comparing their performance with that of the standard/traditional usability heuristics. The study yielded positive results in terms of the number of usability flaws identified and the severity ranking assigned.

Navigation techniques for small-screen devices: An evaluation on maps and web pages

Several techniques have been proposed to support user navigation of large information spaces (e.g., maps or web pages) on small-screen devices such as PDAs and Smartphones. In this paper, we present the results of an evaluation that compared three of these techniques to determine how they might affect performance and satisfaction of users. Two of the techniques are quite common on mobile devices: the first one (DoubleScrollbar) is the standard combination of two scrollbars for separate horizontal and vertical scrolling with zoom buttons to change the scale of the information space, the second one (Grab&Drag) enables users to navigate the information space by directly dragging its currently displayed portion, while zooming is handled through a slider control. The last technique (Zoom-Enhanced Navigator or ZEN) is an extension and adaptation to mobile screens of Overview&Detail approaches, which are based on displaying an overview of the information space together with a detail view of a portion of that space. In these approaches, navigation is usually supported by (i) highlighting in the overview which portion of space is displayed in the detail view, and (ii) allowing users to move the highlight within the overview area to change the corresponding portion of space in the detail area. Our experimental evaluation concerned tasks involving maps as well as web page navigation. The paper analyzes in detail the obtained results in terms of task completion times, number and duration of user interface actions, accuracy of the gained spatial knowledge, and subjective preferences.

A Review of Online Advertising Effects on the User Experience

This article reviews empirical research conducted in the last decade on the subject of how online display advertising affects the usability and quality of user experience of websites. In particular, from an in-depth analysis of research questions, methods, and findings of the reviewed studies, the following is discussed: (a) which conceptual and theoretical background knowledge, based on psychological explanations of user cognition, affection and behavior, can best support the design and investigation of online advertising, and (b) which specific adverts features and properties are key to understand and favor certain types of effects on users. By capitalizing on this benchmark knowledge on benefits of adverts and their hidden costs, web researchers and practitioners are encouraged to approach online advertising from a deeper and more comprehensive perspective, which is centered on qualities of web interaction that go beyond traditional usability factors. It is speculated that many of the theories and models developed for advertising effectiveness, and variables used to measure it, could and should be applied also when assessing the quality of the user experience when using websites in general, regardless of whether they contain adverts.

A Web-based Tool for Collaborative Access to Scientific Instruments in Cyberinfrastructures

Cyberinfrastructures that are being built in the United States and in Europe have the goal of enabling large-scale distributed science and engineering collaborations. However, there is still the need for effective groupware tools that will enable distributed and heterogeneous teams of people to effectively collaborate within these global scenarios. This chapter presents a Web-based groupware tool that is being developed in the context of the GRIDCC European project, whose purpose is to extend current cyberinfrastructures to enable shared access to and control of distributed instrumentation. We discuss the challenges in developing groupware solutions for different social and organizational contexts, and present the main features of a prototype we have designed.

Supporting cognitive walkthrough with video data: a mobile learning evaluation study

Although expert-based evaluation techniques such as heuristic evaluation and cognitive walkthrough are often inexpensive and quick to apply, they have not proved to be effective in capturing contextual factors that arise in real-world settings. It is no trivial issue to understand how such evaluation techniques could be modified or differently applied so as to better take into account context, without loosing the advantages inherent in those techniques. This paper explores a possible way of addressing the trade-off between application of cognitive walkthrough and low cost improvements of its contextual validity. In particular, we propose and investigate the benefits of supporting cognitive walkthrough with video data about user interaction with an eLearning course on mobile device. Initial results from this study indicated that video data provided evaluators with a more detailed understanding of user characteristics and interaction contexts, leading to an improvement of their assessments in terms of the total number of systems flaws detected. Video data was regarded by experts as both relevant and useful, especially for tuning the evaluation focus on types of difficulties they would normally not have experienced because of differences in terms of abilities, knowledge and background with those of the target user group.

Accessible e-learning material: a no-frills avenue for didactical experts

Different organizations adopt accessibility for various and diverse reasons. Interesting and inspiring as such reasons may be, it is important to ensure that the motivation for supporting accessibility is that it is the right thing to do, i.e. a commitment to the provision of equal opportunities for accessing resources for people with special needs. Among the various efforts for supporting the development of accessible e-learning material, most of them propose guidelines that prevalently address technical accessibility issues (such as the format and navigation of learning material) with little or no consideration for the didactical experts, and thus their didactical experience, in developing learning material. Moreover, the aforementioned guidelines tend to provide generic indications on alternative forms of didactical content for equivalent access to it. None the less, the sole provision of equivalent forms does not guarantee the retention of desirable user interface aspects and may therefore have a negative impact on learning effectiveness. While this paper acknowledges the role of such guidelines, it does propose that the didactical experts be provided with a non-technical recourse, improving their development of accessible e-learning content. By tapping into the experience of the didactical experts, this work provides them with an avenue leading to enhance the accessibility of e-learning material.

Scaffolding the design of accessible eLearning content: a user-centered approach and cognitive perspective

There exist various guidelines for facilitating the design, preparation, and deployment of accessible eLearning applications and contents. However, such guidelines prevalently address accessibility in a rather technical sense, without giving sufficient consideration to the cognitive aspects and issues related to the use of eLearning materials by learners with disabilities. In this paper we describe how a user-centered design process was applied to develop a method and set of guidelines for didactical experts to scaffold their creation of accessible eLearning content, based on a more sound approach to accessibility. The paper also discusses possible design solutions for tools supporting eLearning content authors in the adoption and application of the proposed approach.

Interaction-Based adaptation for small screen devices

This paper explores an original approach to overcome current issues in the use of mobile devices, such as limited screen space and interaction modalities, based on exploiting interface adaptation and adaptive techniques. Specifically, the paper describes the application of this approach to a web searching prototype, which collects usage data to model interaction and provide a personalized version of the web facility visited by the user.

The design of an authoring interface to make elearning content accessible

This paper presents the rationale and design process of an authoring interface that enables didactic experts to create or modify eLearning content to make it accessible by learners with special needs. The tool has been designed according to a methodological framework and a set of guidelines for eLearning accessibility previously developed by our group. A key aspect of our framework consists in helping authors to preserve the didactic quality of the eLearning experiences provided to disabled learners (in particular, visually impaired ones) beyond assuring their mere physical access to online materials. A user-centred design process has been adopted to develop a usable prototype of the authoring interface, named aLearning, that we describe below.