This work describes the iterative design and development of a Virtual Reality (VR) tool intended to explore how immersive technologies can support autistic adolescents when facing everyday situations characterised by uncertainty. We report the results of a co-design workshop with four psychologists specialised in neurodevelopmental intervention, which led to the creation of storyboards about uncertainty in a supermarket context. Results include sensory and social considerations in the simulation of uncertainty, as well as coping strategies and design implications for virtual environments with potential clinical relevance. These storyboards were used to develop a mid-fidelity prototype of a VR system. We then invited six autistic adolescents (aged 10-18) to interact with the prototype and act as expert advisors. Feedback data were gathered through semi-structured interviews and field observations. Our findings reveal that designing for autonomy in VR experiences is shaped by tensions related to individual, social, and interactive aspects. This work contributes to research on designing VR tools for autistic people by providing critical reflections on autonomy, competence, and relatedness.

Test anxiety involves feelings of discomfort, fear and worry, impacting students’ wellbeing and academic performance. Virtual reality exposure (VRE) shows promise in mitigating test anxiety, but existing applications concern only written exams. Few VRE applications simulate one-on-one interviews with examiners, and applications for public speaking focus on formal presentations before an audience. This paper concerns a trial of a VRE application that deals with oral exams, presenting a qualitative study of a sample of undergraduate students who autonomously used the VRE application in their homes over three weeks. The application exposes students to scenarios in which a virtual examiner displays friendly, partially friendly, or unfriendly behaviour while asking questions selected from a pool defined by the student. Participants were interviewed to investigate their perceptions of and experience with the application. Thematic analysis of participants’ interviews indicates that they perceived the VRE application as valuable not only for studying and practicing oral exams but also for handling emotional aspects associated with the exam. Moreover, the application helped to increase confidence and awareness of preparation level among some participants. Finally, the paper describes participants’ suggestions emerged from the study that can be used to inform the design of this type of applications.

Convincing crowd behavior simulation is becoming essential in many application domains, including video games, cinematography, urban planning, safety simulations, and training. In this article, we propose a novel and lightweight mesoscopic system for personality-based crowd simulation in immersive virtual reality (iVR). We use the Big Five personality framework, also known as OCEAN, to model a synthetic personality for each autonomous agent. Agents can autonomously aggregate in formations using machine learning-based clustering techniques operating on OCEAN. Moreover, agents can also externalize their personality traits by performing peculiar behavioral animations. To choose which animations to perform, we adopt a probabilistic approach that considers each OCEAN dimension as a continuous spectrum with two extremes linked to pairs of animations. Our system is designed to be flexible and suitable for different applications. Flexibility is achieved by using graphs to store agent and map topology data that control how the agents move and behave at runtime. In a within-subjects study with 40 users, we compare our personality-based system against a basic system that does not use personality. Results show that introducing personality into iVR crowd simulation enhances users' social presence and experienced realism. Introducing personality also increases the perceived match between the agents and the virtual environment where the simulation takes place.

Abstract Test anxiety is an emotional state characterized by subjective feelings of discomfort, fear, and worry that can considerably affect students’ academic performance. Virtual Reality exposure (VRE) is a promising approach to address test anxiety, but the few VRE systems for test anxiety in the literature concern only written exams. Since oral exams elicit more anxiety than written exams, the availability of VRE systems for oral exams would be precious to a large population of students worldwide. Another limitation of existing VRE systems for test anxiety is that they require the availability of a head-mounted display, posing a barrier to widespread use. This paper aims to address both issues, proposing a VRE system that deals with oral exams and can be used with common PC displays. The design of the proposed system is organized in three oral test scenarios in which a virtual agent acts as the student’s examiner. The virtual examiner behaves friendly in the first scenario and increasingly reduces its friendliness in the two subsequent scenarios. The paper assesses the feasibility for VRE of the proposed system with two complementary methods. First, we describe a quantitative user study of the three system scenarios, showing that they induce increasing levels of anxiety. Second, we present a qualitative thematic analysis of participants’ post-exposure interviews that sheds further light on the aspects of the virtual experience that contributed to eliciting negative or positive affect in participants, and provides insights for improving VRE systems for test anxiety.

Digital games for education and training, also called serious games (SGs), have shown beneficial effects on learning in several studies. In addition, some studies are suggesting that SGs could improve user's perceived control, which affects the likelihood that the learned content will be applied in the real world. However, most SG studies tend to focus on immediate effects, providing no indication on knowledge and perceived control over time, especially in contrast with nongame approaches. Moreover, SG research on perceived control has focused mainly on self-efficacy, disregarding the complementary construct of locus of control (LOC). This article advances both lines of research, assessing user's knowledge and LOC over time, with a SG as well as traditional printed materials that teach the same content. Results show that the SG was more effective than printed materials for knowledge retention over time, and a better retention outcome was found also for LOC. An additional contribution of the paper is the proposal of a novel SG that targets the inclusivity goal of safe evacuation for all, extending SG research to a domain not dealt with before, i.e., assisting persons with disabilities in emergencies.

The fidelity level of virtual reality (VR) setups can affect different aspects of virtual experiences, but its effects on knowledge acquisition and retention need clarification. The two studies in this paper focus on spatial knowledge. The first study compared three VR setups, one using a VR headset and two using a tablet, differing in display and interaction fidelity. Since the type of virtual environment (VE), and the locomotion technique employed to explore it, might affect spatial knowledge acquisition, we studied each setup in an indoor and an outdoor VE with two widely used locomotion techniques (teleport and steering). Results showed that setups offering higher display and interaction fidelity can improve acquisition of spatial knowledge in terms of distance estimations (with teleport in the indoor VE, and with steering in the outdoor VE) and object-to-object spatial relations (with steering in the outdoor VE), but not in terms of object locations. This can provide guidance about how to choose the appropriate combination of setup and locomotion technique based on the type of VE and the types of spatial knowledge to acquire. Moreover, sickness and usability results showed that VR headset was more usable than tablet, and suggest using teleport on VR headset and steering on tablet. Therefore, the second study focused on VR headset with teleport and tablet with steering, and extended the assessment of their effects to spatial knowledge retention after two weeks. Results showed that spatial knowledge decreased in both conditions, but the VR headset with teleport led to better acquisition and 2-weeks retention of distance estimations.

Recent years have witnessed a growing interest in serious games (SGs), i.e., digital games for education and training. However, although the potential scalability of SGs to large player populations is often praised in the literature, available SG evaluations did not provide evidence of it because they did not study learning on large, varied, international samples in naturalistic conditions. This article considers a SG that educates players about aircraft cabin safety. It presents the first study of learning in a SG intervention conducted in naturalistic conditions with a very large, worldwide sample, which includes 45,000 players who accepted to answer a knowledge questionnaire before and after playing the game, and more than 400,000 players whose in-game behavior was analyzed. Results show that the SG led to improvement in players' knowledge, assessed with different metrics. Moreover, analysis of repeated play shows that participants improved their in-game safety behavior over time. We also focus on the role of making errors in the game, showing how they led to improvement in knowledge. Finally, we highlight the theoretical models, such as error-based learning and Protection Motivation Theory, that oriented the game design, and can be reused to create SGs for other domains.

Recent VR head-mounted displays for consumers feature 3-DOF or 6-DOF head tracking. However, position tracking (when available) is limited to a small area. Moreover, in small or cluttered physical spaces, users can safely experience VR only by staying in place, standing or seated. Different locomotion techniques have been proposed to allow users to explore virtual environments by staying in place. Two in-place locomotion techniques, frequently employed in the literature and in consumer applications, are based on joystick and teleport. Some authors explored leaning with the aim of proposing a more natural in-place locomotion technique. However, more research is needed to understand the effects of the three techniques, since no user study thoroughly compared them all together on a variety of fundamental aspects. Therefore, this paper presents a comparative evaluation with 75 users, assessing the effects of the three techniques on performance, sickness, presence, usability, and different aspects of comfort. Performance of teleport was better than the other techniques, and performance of leaning was better than joystick. Teleport also caused less nausea than the other techniques. Unexpectedly, no significant differences were found for presence. Teleport received a higher usability score than the other techniques. Finally, the techniques had different effects on comfort that we discuss in detail.

Head-mounted displays (HMDs) are increasingly available to users after the launch of new-generation consumer devices. Moreover, mobile HMDs such as Samsung Gear VR and Google Daydream View allow users to experience VR through a smartphone, without requiring connection to a PC. Commercial applications for mobile HMDs exploit different techniques to perform menu selection tasks. This paper contrasts the two most used techniques, i.e., dwell-based and touchpad-based selection, which were not experimentally compared before. We consider different versions of a menu pointing and selection task in which participants interacted with a Samsung Gear VR. Results show that participants were slower with the dwell-based technique rather than the touchpad-based technique. However, the dwell-based technique led to fewer errors and was perceived as more usable, more comfortable and less fatiguing than the touchpad-based technique. We also evaluated two different active areas for the selection, discussing the results.

Recently, Tangible and Embodied Interaction (TEI) approaches to support people in mindfulness practices have been proposed in the literature, but they have scarcely explored the use of real natural elements in the interaction. In this article, we first present TANGAEON, a TEI system that augments the AEON mindfulness mobile app with an interactive, water-filled glass container. Second, we evaluate TANGAEON by contrasting it with two traditional mindfulness techniques and with AEON. TANGAEON obtained better results in terms of achieved mindfulness, perceived level of difficulty, and degree of pleasantness than the two traditional techniques. Moreover, considering all techniques, participants achieved the highest level of mindfulness with TANGAEON, and rated it as the most pleasant and preferred approach to practice. These results suggest that the use of TEI based on a natural element can offer a novel and effective way to help people approach and practice mindfulness, and to augment existing mindfulness apps.

The increasing availability of head-mounted displays (HMDs) for home use motivates the study of the possible effects that adopting this new hardware might have on users. Moreover, while the impact of display type has been studied for different kinds of tasks, it has been scarcely explored in procedural training. Our study considered three different types of displays used by participants for training in aviation safety procedures with a serious game. The three displays were respectively representative of: (i) desktop VR (a standard desktop monitor), (ii) many setups for immersive VR used in the literature (an HMD with narrow field of view and a 3-DOF tracker), and (iii) new setups for immersive home VR (an HMD with wide field of view and 6-DOF tracker). We assessed effects on knowledge gain, and different self-reported measures (self-efficacy, engagement, presence). Unlike previous studies of display type that measured effects only immediately after the VR experience, we considered also a longer time span (2 weeks). Results indicated that the display type played a significant role in engagement and presence. The training benefits (increased knowledge and self-efficacy) were instead obtained, and maintained at two weeks, regardless of the display used. The paper discusses the implications of these results.

The computational capabilities of today's smartphones make it possible to take advantage of mobile three-dimensional (3-D) maps to support navigation in the physical world. In particular, 3-D maps might be useful to facilitate indoor wayfinding in large and complex buildings, where the typical orientation cues (e.g., street names) and location tracking technologies that can be used outdoors are unavailable. The use of mobile 3-D maps for indoor wayfinding is still largely unexplored and research on how to best design such tools has been scarce to date. One overlooked but important design decision for 3-D maps concerns the perspective from which the map content should be displayed, with first-person and third-person perspectives being the two major options. This paper presents a user study involving wayfinding tasks in a large and complex building, comparing a mobile 3-D map with first-person perspective, a mobile 3-D map with third-person perspective, and a traditional mobile 2-D map. The first-person perspective shows the mobile 3-D map of the building from a floor-level egocentric point of view, whereas the third-person perspective shows the surroundings of the user from a fixed distance behind and above her position. Results of the study reveal that the mobile 3-D map with third-person perspective leads to shorter orientation time before walking, better clarity ratings, lower workload, mental demand and effort scores, and higher preference score compared to the mobile 3-D map with first-person perspective. Moreover, it leads to shorter orientation time before walking, better pleasantness ratings, lower mental demand scores, and higher preference score compared to the mobile 2-D map.

Persuasive Technology (PT) is an interdisciplinary research field that focuses on the design and development of technologies aimed at changing users[#x02019] attitudes or behaviors through persuasi...

Interactive systems are increasingly used in a growing number of domains to encourage users to perform certain actions or take a certain position toward a given subject. This article offers a perspective on interactive persuasive systems that emphasizes theories and concepts that can guide their design and evaluation. The goal is not to champion a theoretical model over others or to compare the effectiveness of different persuasive strategies but rather to depict the current conceptual landscape in this field and highlight emerging concepts and positions that have recently appeared in it. The article includes a discussion of some representative, general, and domain-specific constructs that can be used to evaluate the effectiveness of interactive persuasive systems.

Mindfulness is attracting an increasing interest due to its health and well-being benefits, but its practice can be difficult for people with no or minimal experience with meditation. In this study, we aim at thoroughly investigating participants' user experience with a mobile mindfulness app (AEON). In particular, we focus on perceptions in using the app for ameliorating worry, as well as on understanding in situ usage. We employ thematic analysis to qualitatively analyze participants' interviews at the end of a 5-week study period. Results indicate that several participants experienced decentering from their worries when using the app. Moreover, AEON was perceived as easy and pleasant to use. However, results also highlight that some participants did not experience decentering from all or some of their worries, and we discuss the possible reasons. Finally, unexpected patterns of use, user's suggestions and some usability problems emerged from the study, allowing us to identify some design opportunities for mindfulness apps.

Serious games for safety education (SGSE) are a novel tool for preparing people to prevent and\or handle risky situations. Although several SGSE have been developed, design and evaluation methods for SGSE need to be better grounded in and guided by safety-relevant psychological theories. In particular, this paper focuses on threat appeals and the assessment of variables, such as safety locus of control, that influence human behavior in real risky situations. It illustrates how we took into account such models in the design and evaluation of "Learn to Brace", a first-of-its-kind serious game that deals with a major problem in aviation safety, i.e. the scarce effectiveness of the safety cards used by airlines. The study considered a sample of 48 users: half of them received instructions about the brace position through the serious game, the other half through a traditional safety card pictorial. Results showed that the serious game was much more effective than the traditional instructions both in terms of learning and of changing safety-relevant perceptions, especially safety locus of control and recommendation perception.

Thanks to the increasing availability of consumer head-mounted displays, educational applications of immersive VR could now reach to the general public, especially if they include gaming elements (immersive serious games). Safety education of citizens could be a particularly promising domain for immersive serious games, because people tend not to pay attention to and benefit from current safety materials. In this paper, we propose an HMD-based immersive game for educating passengers about aviation safety that allows players to experience a serious aircraft emergency with the goal of surviving it. We compare the proposed approach to a traditional aviation safety education method (the safety card) used by airlines. Unlike most studies of VR for safety knowledge acquisition, we do not focus only on assessing learning immediately after the experience but we extend our attention to knowledge retention over a longer time span. This is a fundamental requirement, because people need to retain safety procedures in order to apply them when faced with danger. A knowledge test administered before, immediately after and one week after the experimental condition showed that the immersive serious game was superior to the safety card. Moreover, subjective as well as physiological measurements employed in the study showed that the immersive serious game was more engaging and fear-arousing than the safety card, a factor that can contribute to explain the obtained superior retention, as we discuss in the paper.

Virtual Reality (VR), in the form of 3D interactive simulations of emergency scenarios, is increasingly used for emergency preparedness training. This paper advances knowledge about different aspects of such virtual emergency experiences, showing that: (i) the designs we propose in the paper are effective in improving emergency preparedness of common citizens, considering aviation safety as a relevant case study, (ii) changing specific visual and auditory features is effective to create emotionally different versions of the same experience, increasing the level of fear aroused in users, and (iii) the protection motivation role of fear highlighted by psychological studies of traditional media applies to desktop VR too.

Anxiety induction and elicitation of associated physiological arousal with virtual environments (VEs) is important in diverse domains. This paper evaluates three general anxiety induction techniques. The first augments the VE with a health bar that is often displayed in video games to indicate when the user's avatar gets hurt. The second augments the VE with aversive audio-visual stimuli, which are employed in first-person shooter games when the user's avatar gets hurt and include preset heartbeat sound. The third introduces in the previous technique a biofeedback mechanism to control heartbeat sound. The results we obtained on a VE that reproduces a fire evacuation indicate that the third technique produces much higher physiological arousal than the other two, and measures of users’ state anxiety are consistent with physiological results. We discuss possible reasons that could explain why the exploitation of auditory heartbeat biofeedback contributes to make the third technique more effective, by linking our study to research and theories of affect and emotions.

In affective computing, detection of stress and negative emotions with physiological measures typically employs well-known signals such as skin conductance, activity of cheeks and forehead muscles, heart rate or heart rate variability. However, psychophysiology experiments in the literature offer additional measures (such as eye-blink startle response) not yet exploited in affective computing applications. Procedures to elicit eye-blink startle responses are often based on acoustic stimuli, in particular short bursts of intense white noise. Unfortunately, following this approach in affective computing applications would not be natural, because the artificial white noise bursts would be intrusive sounds unrelated to the user experience. They would thus distract the user from the meaningful events in the application and user's (conscious or unconscious) attempts to relate those events to the artificial stimuli would be unsuccessful and frustrating, making the stimuli detrimental to the user experience. Our research aims at exploring if sounds that have a meaningful relation with the events in the application could be used as an alternative to white noise bursts. The study we present in this paper compares physiological responses of users of a 3D virtual environment in two conditions (measurement of eye-blink startle response to white noise or to an alternative sound that is related to the experience), showing that the two types of acoustic stimuli produce a similar intensity of startle response. This result suggests that eye-blink startle response could be used in natural ways to extend the set of physiological measures employed in affective computing.

Overview+Detail [25] and Wedge [16] have been proposed in the literature as effective approaches to resolve the off-screen objects problem on mobile devices. However, they have been studied with a small number of off-screen objects and (in most studies) with static scenarios, in which users did not have to perform any navigation activity. In this paper, we propose improvements to Wedge and Overview+Detail which are specifically aimed at simplifying their use in dynamic scenarios that involve large numbers of off-screen objects. We compare the effectiveness of the two approaches in the considered scenario with a user study, whose results show that Overview+Detail allows users to be faster in searching for off-screen objects and more accurate in estimating their location.

GPS-based pedestrian navigation can be difficult when GPS position readings are inaccurate or unavailable. In this paper, we report on a user study we carried out to investigate whether different visualizations of the uncertainty associated to user position can help users navigate outdoors when the GPS signal is degraded. In the study, we compared a basic visualization that displays only the last accurate position of the user during GPS signal degradation, and two visualizations that dynamically estimate the area where the user might be, displaying it respectively as a circle and as colored street segments. While we did not find any difference among the three visualizations in terms of the accuracy with which users assessed their position, we found that the "streets coloring" visualization required a significantly lower workload compared to the basic visualization and was perceived to be more beneficial by users.

When navigating large information spaces on mobile devices, the small size of the display often causes relevant content to shift off-screen, greatly increasing the difficulty of spatial tasks such as planning routes or finding points of interest on a map. Two possible approaches to mitigate the problem are Contextual Cues, i.e. visualizing abstract shapes in the border region of the view area to function as visual references to off-screen objects of interest, and Overview + Detail, i.e., simultaneously displaying a detail view and a small-scale overview of the information space. In this paper, we compare the effectiveness of two different Contextual Cues techniques, Wedge (Gustafson et al., 2008) and Scaled Arrows (Burigat et al., 2006), and a classical Overview + Detail visualization that highlights the location of objects of interest in the overview. The study involved different spatial tasks and investigated the scalability of the considered visualizations, testing them with two different numbers of off-screen objects. Results were multifaceted. With simple spatial tasks, no differences emerged among the visualizations. With more complex spatial tasks, Wedge had advantages when the task required to order off-screen objects with respect to their distance from the display window, while Overview + Detail was the best solution when users needed to find those off-screen objects that were closest to each other. Finally, we found that even a small increase in the number of off-screen objects negatively affected user performance in terms of accuracy, especially in the case of Scaled Arrows, while it had a negligible effect in terms of task completion times.

Fast and effective communication is crucial during medical emergencies, but patients' disabilities can make it a challenging task for emergency medical responders. This paper proposes a mobile system to deal with the communication barrier between medical responders and deaf patients. The system allows medical responders to quickly browse a collection of emergency-related sentences, and show videos of the corresponding translations in sign language to the deaf patients. The design process involved experts in emergency medicine as well as experts from the deaf community. The evaluation carried out on ten emergency medical responders and ten deaf subjects showed that the system is useful to support communication with deaf people during medical emergencies.

Searching for an item in a long ordered list that does not fit the screen is a frequent task when using mobile devices. This paper explores four different interfaces to support blind users in carrying out this task. Two of them are based on the idea of tree-augmentation of a list, proposed by Furnas [3], and differ in their depth versus breadth ratio. The other two interfaces adopt the more traditional technique of list scrolling based respectively on standard multitap and T9 keyboard entry. The paper reports also on the results of a pilot study of the four interfaces conducted on two blind users.

In this paper, we present MoStarD, a mobile application that couples starfield displays with dynamic queries to support user exploration of large datasets. A novel space compression technique enables users to compress areas of the starfield display to optimize screen space usage and easily focus on specific subsets of a dataset.

Arranging 3D objects in Virtual Environments can be a complex, error prone and time consuming task, especially for users who are not familiar with interfaces for 3D navigation and object manipulation. In this paper, we analyze and compare novice users' performance on 3D object arrangement tasks using three interfaces that differ in the views of the 3D environment they provide: the first one is based only on a first-person view; the second one combines the first-person view and a map view in which the zoom level is manually controlled by the user; the third one extends the second with automated assistance in controlling the map zoom level during object manipulation. Our study shows that users without prior experience in 3D object arrangement prefer and actually benefit from having a map view in addition to a first person view in object arrangement tasks.

This demo will illustrate the adaptive interface of an application (whose architecture and implementation have been presented in detail in [2]) for learning 3D Graphics programming (in the X3D ISO standard). The application situates users in a 3D Virtual Environment where they can learn by selecting and inspecting actual examples.

This paper presents a study comparing two Zoomable User Interfaces with Overviews (ZUIOs) against a classic Zoomable User Interface (ZUI) in the context of user navigation of large information spaces on mobile devices. The study aims at exploring (i) if an overview is worth the space it uses as an orientation tool during navigation of an information space and (ii) if part of the lost space can be recovered by switching to a wireframe visualization of the overview and dropping semantic information in it. The study takes into consideration search tasks on three types of information space, namely maps, diagrams, and web pages, that widely differ in structural complexity. Results suggest that overviews bring enough benefit to justify the used space if (i) they highlight relevant semantic information that users can exploit during search and (ii) the structure of the considered information space does not provide appropriate orientation cues.

Natural and man-made disasters present the need to efficiently and effectively evacuate the people occupying the affected buildings. Providing appropriate evacuation instructions to the occupants of the building is a crucial aspect for the success of the evacuation. This paper presents an approach for giving evacuation instructions on mobile devices based on interactive location-aware 3D models of the building. User's position into the building is determined by using active short-range RFID technology. A preliminary user evaluation of the system has been carried out in the building of our Department.

The capability of accessing, analyzing and possibly updating patients' medical records from anywhere through a mobile device in the hands of clinicians and nurses is considered to be a particularly promising application. Information Visualization has explored interactive visual formats to help users in analyzing patient records, but they are meant for the desktop context. This paper begins to explore the problem of visualizing patient record data with the limited display and interaction capabilities of mobile devices, focusing on common PDAs and temporal data.

Embodied agents are employed in several applications (e.g. computer-based presentations, help systems, e-learning and training, sign language communication for the deaf), but the process of developing them is still complex (e.g., modeling animations is one of the difficult and time-consuming tasks). Moreover, although mobile devices have recently reached a performance level that allows them to manage 3D graphics, most embodied agents run on desktop computers only. The aim of our research is twofold: (i) proposing a tool that allows novice users to approach the animation modeling process of 3D anthropomorphic agents in a simple way, and (ii) proposing a 3D player to display these animated agents on PDAs. Besides discussing in detail the proposed system, the paper reports about its informal evaluation and two of its applications: sign language animation for the deaf and mobile fitness training.

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.

Sports and fitness are increasingly attracting the interest of computer science researchers as well as companies. In particular, recent mobile devices with hardware graphics acceleration offer new, still unexplored possibilities. This paper investigates the use of mobile guides in fitness activities, proposing the Mobile Personal Trainer (MOPET) application. MOPET uses a GPS device to monitor user's position during her physical activity in an outdoor fitness trail. It provides navigation assistance by using a fitness trail map and giving speech directions. Moreover, MOPET provides motivation support and exercise demonstrations by using an embodied virtual trainer, called Evita. Evita shows how to correctly perform the exercises along the trail with 3D animations and incites the user. To the best of our knowledge, our project is the first to employ a mobile guide for fitness activities. The effects of MOPET on motivation, as well as its navigational and training support, have been experimentally evaluated with 12 users. Evaluation results encourage the use of mobile guides and embodied virtual trainers in outdoor fitness applications.

Virtual environments (VEs) very often contain buildings that have to be navigated by users. In the literature, several navigation aids based on maps have been proposed for VEs, but in virtual buildings they have been typically used for single-floor scenarios. In this paper, we propose and experimentally evaluate two different navigation aids for multi-floor virtual buildings, one based on 3D maps and the other based on 2D maps. We compared subjects' performance with two different types of tasks: search and direction estimation. While the 2D navigation aid outperformed the 3D one for the search task, there were no significant differences between the two aids for the direction estimation task.

This paper presents a tool for the visual analysis of navigation patterns of moving entities, such as users, virtual characters, or vehicles in 3D Virtual Environments (VEs). The tool, called VU-Flow, provides a set of interactive visualizations that highlight interesting navigation behaviors of single or groups of moving entities that were the VE together or separately. The visualizations help to improve the design of VEs and to study the navigation behavior of users, e.g., during controlled experiments. Besides VEs, the proposed techniques could also be applied to visualize real-world data recorded by positioning systems, allowing one to employ VU-Flow in domains such as urban planning, transportation, and emergency response.

In this paper, we propose the Interactive 3D BreakAway Map (I3BAM), an extension of the well-known Worlds In Miniature (R. Stoakley et al., 1995). The I3BAM supports user navigation in virtual buildings as a navigation aid, but also provides a means of examining any floor of a virtual building without having to necessarily navigate it. The aid presents multiple views of a virtual building and provides information about both the internal and external structure of a building. The paper also includes some implementation details and shows an application of the I3BAM to help users learn how to navigate real buildings.

Educational virtual worlds (EVWs) allow one to circumvent physical, safety, and cost constraints that often affect real-world training and learning scenarios. Virtual humans can improve the effectiveness of an EVW e.g., by explaining and demonstrating to the user procedural tasks and communicating with learners in a natural way by exploiting both verbal and nonverbal communication. However, choosing how the learning material has to be presented to the learner and how to employ the virtual human is influenced by different factors, ranging from available technology (e.g., bandwidth, graphics hardware, installed software) to learner's profile (e.g., physical and/or cognitive disabilities, spatial abilities, 2D/3D navigation expertise). The system we present in this paper flexibly supports different presentation techniques employing a virtual human into an EVW. The different capabilities of the system are illustrated, motivated and discussed.

In this paper, we present the Interactive 3D BreakAway Map (I3BAM), an extension of Worlds In Miniature (WIM) that works not only as a navigation aid for virtual buildings but also provides a means of examining any floor of a virtual building without having to navigate it. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Supporting users' navigation is a fundamental feature of mobile guides. This paper presents an experimental evaluation comparing three different ways of providing navigation guidance by combining visual and audio directions during guided city tours. The three considered solutions differ in the way audio directions are augmented with visual directions: a traditional map-based solution, a combination of a map and photographs of the area, a combination of large arrows and photographs.The results of our evaluation show that when the map is combined with photographs that clearly indicate the direction to the user or when the map is replaced by a combination of directional arrows and photographs, users' performance is significantly better. Moreover, the combination of map and photographs was highly preferred by users.

The navigation support provided by user interfaces of Virtual Environments (VEs) is often inadequate and tends to be overly complex, especially in the case of large-scale VEs. In this paper, we propose a novel navigation aid that aims at allowing users to easily locate objects and places inside large-scale VEs. The aid exploits 3D arrows to point towards the objects and places the user is interested in. We illustrate and discuss the experimental evaluation we carried out to assess the usefulness of the proposed solution, contrasting it with more traditional 2D navigation aids. In particular, we compared subjects' performance in 4 conditions which differ for the type of provided navigation aid: three conditions employed respectively the proposed "3D arrows" aid, an aid based on 2D arrows, and a 2D aid based on a radar metaphor; the fourth condition was a control condition with no navigation aids available.

Although some guidelines (e.g., based on architectural principles) have been proposed for designing Virtual Environments (VEs), several usability problems can be identified only by studying the behavior of real users in VEs. This paper proposes a tool, called VU-Flow, that is able to automatically record usage data of VEs and then visualize it in formats that make it easy for the VE designer to visually detect peculiar users' behaviors and thus better understand the effects of her design choices. In particular, the visualizations concern: i) the detailed paths followed by single users or groups of users in the VE, ii) areas of maximum (or minimum) users' flow, iii) the parts of the environment more seen (or less seen) by users, iv) detailed replay of users visits. We show examples of how these visualizations allow one to visually detect useful information such as the interests of users, navigation problems, users' visiting style. Although this paper describes how VU-Flow can be used in the context of VEs, it is interesting to note that the tool can be also applied to the study of users of location-aware mobile devices in physical environments.

Abstract This paper presents a system for realistic behavioral programming of virtual characters, based on personality and probabilistic automata. We describe personality by using the Five‐Factor Model and achieve autonomy through a goal‐oriented approach. Each character perceives the surrounding world, decides how to behave and acts on the environment according to its personality and to its goals. The chief idea explored by the proposed approach is that personality has a probabilistic influence on behavior selection instead of a deterministic one. Different behavior sequences available to achieve a goal are modeled using probabilistic automata and making probability dependent on character personality. This leads to non‐repetitive behaviors, whose evolution is not foreseeable. The paper first motivates the approach in the context of cybertherapy. Then, it summarizes related work and illustrates in detail the proposed approach. Finally, it presents obtained results and discusses the main limitations of the implemented system. Copyright © 2004 John Wiley & Sons, Ltd.

Virtual Reality (VR) interfaces to e-commerce sites have recently begun to appear on the Internet, promising to make the e shopping experience more natural, attractive, and fun for customers. Unfortunately, switching to a desktop VR design for an e-commerce site is not trivial and does not guarantee at all that the interface will be effective. In this paper, we first briefly discuss the potential advantages of these interfaces, stressing the need for a better approach to their design. Then, we present the directions we are following to build more usable and effective VR stores, i.e.: (i) reformulating design guidelines from real-world stores in the VR context, (ii) exploiting VR to create user empowerments that meet both customer and merchant needs, and (iii) personalizing the VR store to better reflect customer's taste, preferences, and interests. For each of the three directions, we illustrate and discuss a detailed case study.

A crucial component for turning any temporal reasoning system into a real-world application that can be adopted by a wide base of users is given by its user interface. After analyzing and discussing the state of the art for the visualization of temporal intervals and relations, this paper proposes three new solutions, also evaluating them with a proper user study.

A relevant issue for any Virtual Environment (VE) is the navigational support provided to users who are exploring it. Semitransparency is sometimes exploited as a means to see through occluding surfaces with the aim of improving user navigation abilities and awareness of the VE structure. Designers who make this choice assume that it is useful, especially in the case of VEs with many levels of occluding surfaces, e.g. virtual buildings or cities. This paper is devoted to investigate this assumption with a proper experimental evaluation on users. First, we discuss possible ways for improving navigation, and focus on implementation choices for semitransparency as a navigation aid. Then, we present and discuss the experimental evaluation we carried out. We compared subjects' performance in three conditions: local exploitation of semitransparency inside the VE, a more global exploitation provided by a bird's-eye-view, and a control condition where neither of the two features was available.

This article deals with the problem of providing Kowalski and Sergot's event calculus, extended with context dependency, with an efficient implementation in a logic programming framework. Despite a widespread recognition that a positive solution to efficiency issues is necessary to guarantee the computational feasibility of existing approaches to temporal reasoning, the problem of analyzing the complexity of temporal reasoning programs has been largely overlooked. This article provides a mathematical analysis of the efficiency of query and update processing in the event calculus and defines a cached version of the calculus that (i) moves computational complexity from query to update processing and (ii) features an absolute improvement of performance, because query processing in the event calculus costs much more than update processing in the proposed cached version.

The basic concepts of the multimodeling approach to the representation of physical systems are presented. Emphasis is placed on the exploitation of many, diverse models of a system for the execution of complex problem solving tasks, such as interpretation, diagnosis, design, simulation, etc. The considered models are based on different ontologies, representational assumptions, epistemological types, and aggregation levels. After a brief survey of the techniques adopted for representing structural and behavioral knowledge, attention is focused on function and teleology. A novel approach is proposed for defining, representing, and using these two types of knowledge which play a fundamental role both from the representation and reasoning perspectives. The fundamental claim is that while teleological knowledge concerns the specific purposes for which the system has been designed, functional knowledge is devoted to bridge the gap between such abstract purposes and the actual structure and behavior of the system, through the concepts of phenomena, processes, and functional roles. A clear definition is provided of all the various epistemological and ontological links existing between the different models.>