Antonio Krüger

Universität des Saarlandes | UKS · Department of Computer Science

One of the advantages of formalizing domain knowledge in OWL ontologies is that one can use reasoning systems to infer implicit information automatically. However, it is not always straightforward to understand why certain entailments are inferred, and others are not. The popular ontology editor Protégé offers two explanation services to deal with...

Entertainment media, including video games, utilize background music (BGM) to enhance ambiance and gameplay, with a growing trend of players replacing in-game audio with personal music for potentially improved gameplay. Yet, research has not systematically investigated the connection between liked or disliked BGM and player behavior and experience....

In gamification users show increased motivation and engagement towards tasks. So far, this effect has mostly been empirically tested based on the visual depiction of game elements, while research on the use and addition of auditory aspects is sparse. In this work we investigate the effect of different modalities of game elements (auditory, visual,...

Background Surgical procedures on the lower extremities often require weight-bearing on crutches as part of the rehabilitation process. Orthopedic elective procedures enable patients to learn the correct use of crutches in a controlled preoperative setting. Digital assistance systems can safely circumvent a shortage of skilled staff and any contact...

Teaching medical practical and soft skills in clinical routines is increasingly difficult, and manikin or actor-based simulations have gained popularity in the last decades. These simulations, however, hardly scale with the demand, are commonly insufficient to train crucial clinical competencies, and cannot portray complex visual and dynamic sympto...

BACKGROUND Surgical procedures on the lower extremities often require weight-bearing on crutches as part of the rehabilitation process. Orthopedic elective procedures enable patients to learn the correct use of crutches in a controlled preoperative setting. Digital assistance systems can safely circumvent a shortage of skilled staff and any contact...

During interaction with objects in Virtual Reality haptic feedback plays a crucial role for creating convincing immersive experiences. Recent work building upon passive haptic feedback has looked towards fabrication processes for designing and creating proxy objects able to communicate objects’ properties and characteristics. However, such approach...

The perception of gamification elements differs across users, which is why personalizing gamified systems is important. Past research showed that the Hexad user types model is particularly suitable for this purpose by demonstrating correlations between user types and gamification elements. However, previous studies were mostly survey-based, i.e. re...

In the context of game live-streams, we focus on whether audience influence options can be extended beyond the game, e.g., to the streamers' environment (e.g., controlling their room lighting), the streamers themselves (e.g., activating vibration feedback on their forearms) and the streamers' hardware and peripheral devices (e.g., switching key bin...

Producing and consuming live-streamed content is a growing trend attracting many people today. While the actual content that is streamed is diverse, one especially popular context is games. Streamers of gaming content broadcast how they play digital or analog games, attracting several thousand viewers at once. Previous scientific work has revealed...

Virtual reality technology and immersive virtual environments often support realistic hand representations via hand-posture-sensing controllers or hand tracking for natural hand-based interaction. However, one limiting factor remains as the lack of realistic haptic feedback including tactile and proprioceptive cues; even for simple haptic interacti...

Although privacy settings are important not only for data privacy, but also to prevent hacking attacks like social engineering that depend on leaked private data, most users do not care about them. Research has tried to help users in setting their privacy settings by using some settings that have already been adapted by the user or individual facto...

Gamification has been shown to successfully help users in reaching their goals, and enhancing their user experience. However, it has also been criticized for adding arbitrary rewards to non-game activities, which is often perceived as being meaningless. To counter this, we investigate whether physical gamification, i.e. transforming virtual gamific...

Personalizing gameful applications is essential to account for interpersonal differences in the perception of gameful design elements. Considering that an increasing number of people lead sedentary lifestyles, using personalized gameful applications to encourage physical activity is a particularly relevant domain. In this article, we investigate be...

Achievement goals are frequently used to support behavior change. However, they are often not specifically designed for this purpose nor account for the degree to which a user is already intending to perform the target behavior. In this paper, we investigate the perceived persuasiveness of different goal types as defined by the 3x2 Achievement Goal...

Gamification is frequently used to motivate people getting more physically active. However, most systems follow a one-size-fits-all gamification approach, although past research has shown that interpersonal differences exist in the perception of gamification elements. Also, most studies investigating the effects of gamification are rather short, al...

Gamification is frequently used to motivate people getting more physically active. However, most systems follow a one-size-fits-all gamification approach, although past research has shown that interpersonal differences exist in the perception of gamification elements. Also, most studies investigating the effects of gamification are rather short, al...

Achievement goals are frequently used to support behavior change. However, they are often not specifically designed for this purpose nor account for the degree to which a user is already intending to perform the target behavior. In this paper, we investigate the perceived persuasiveness of different goal types as defined by the 3x2 Achievement Goal...

Measure user experience in MR (i.e., AR/VR) user studies is essential. Researchers apply a wide range of measuring methods using objective (e.g., biosignals, time logging), behavioral (e.g., gaze direction, movement amplitude), and subjective (e.g., standardized questionnaires) metrics. Many of these measurement instruments were adapted from use-ca...

In this paper, we analyze a wide range of physiological, behavioral, performance, and subjective measures to estimate cognitive load (CL) during post-editing (PE) of machine translated (MT) text. To the best of our knowledge, the analyzed feature set comprises the most diverse set of features from a variety of modalities that has been investigated...

Personalization is essential for gameful systems. Past research showed that the Hexad user types model is particularly suitable for personalizing user experiences. The validated Hexad user types questionnaire is an effective tool for scientific purposes. However, it is less suitable in practice for personalizing gameful applications, because fillin...

More and more professional translators are switching to the use of post-editing (PE) to increase productivity and reduce errors. Even though PE requires significantly less text production, current computer-aided translation (CAT) interfaces still heavily focus on traditional mouse and keyboard input and ignore other interaction modalities to suppor...

Current advances in machine translation (MT) increase the need for translators to switch from traditional translation to post-editing (PE) of machine-translated text, a process that saves time and reduces errors. This affects the design of translation interfaces, as the task changes from mainly generating text to correcting errors within otherwise...

The shift from traditional translation to post-editing (PE) of machine-translated (MT) text can save time and reduce errors, but it also affects the design of translation interfaces, as the task changes from mainly generating text to correcting errors within otherwise helpful translation proposals. Since this paradigm shift offers potential for mod...

This work proposes a combination of embedded computation and marker tracking to provide more robust augmentations for composed objects in Tangible Augmented Reality. By integrating conductive elements into the tangibles' sides, communication between embedded microprocessors is enabled, such that a connected composition can be computed without relyi...

When configuring furniture during sales consultancy in a furniture store, customers are usually confronted with abstract 2D drawings or simplistic renderings of the discussed configuration on a display. We present a novel application based on virtual reality (VR) to support furniture store consultations. Our system allows customers to elaborate dif...

The idea to enhance the learning experience of e-learning platforms by incorporating measures about the user's cognitive state, e.g. the cognitive load, boredom, or attention, has been proposed several times and shows promising results. However, the works have mostly dealt with conceptual implications and technical possibilities to detect the state...

Creating friend lists offers social network users the ability to select a fine-grained audience for their posts, thereby reducing the amount of unwanted disclosures. However, research has shown that the user burden involved in creating and managing friend lists leads to the fact that this functionality is rarely used, despite its advantages. In thi...

This work aims to explore, design and implement better and intuitive categorization schemes and menu representations for online shops that enrich and improve the shopping experience. We utilize the Apartment metaphor, in which products are categorized into rooms and furniture representing departments and shelves. Furthermore, we developed a realist...

Selecting the right audience for Facebook posts is a task that users often skip, resulting in unwanted post disclosure or avoidance of sharing sensitive posts. We present OmniWedges, a user interface designed to allow users of online social networks to make meaningful decisions on who to share their posts with. Our study results also show that with...

In social networks, it often arises that a post is shared with a broader audience than intended, which is often finally noticed when one of the unintentionally included friends likes or comments on the post. We present an approach for privacy setting adaptation based on in-situ feedback on such social network update notifications. We implemented a...

Tailoring gamified systems has been shown to be appreciated and more effective than "one-size-fits-all" systems. A promising approach is using the Hexad user types model. However, obtaining the Hexad user type requires users to fill out a questionnaire, preventing an automated adaptation. Since smartphone data was shown to be linked to personality...

Washing hands is important for public health as it prevents spreading germs to other people. One of the most important factors in cleaning hands is the hand washing duration. However , people mostly do not wash their hands for a long enough time leading to infections and diseases for themselves and others. To counter this, we present "Germ Destroye...

In automatic post-editing (APE) it makes sense to condition post-editing (pe) decisions on both the source (src) and the machine translated text (mt) as input. This has led to multi-source encoder based APE approaches. A research challenge now is the search for architectures that best support the capture, preparation and provision of src and mt inf...

In this paper, we develop a model that uses a wide range of physiological and behavioral sensor data to estimate perceived cognitive load (CL) during post-editing (PE) of machine translated (MT) text. By predicting the subjectively reported perceived CL, we aim to quantify the extent of demands placed on the mental resources available during PE. Th...

This paper investigates a simple form of customization: giving users the choice to enable or disable gamification. We present a study (N=77) in the context of image tagging, in which a gamification approach was shown to be effective in previous work. In our case, some participants could enable or disable gamification after they had experienced the...

Current advances in machine translation increase the need for translators to switch from traditional translation to post-editing (PE) of machine-translated text, a process that saves time and improves quality. This affects the design of translation interfaces, as the task changes from mainly generating text to correcting errors within otherwise hel...

Experiencing materials in virtual reality (VR) is enhanced by combining visual and haptic feedback. While VR easily allows changes to visual appearances, modifying haptic impressions remains challenging. Existing passive haptic techniques require access to a large set of tangible proxies. To reduce the number of physical representations, we look to...

Standard controllers for virtual reality (VR) lack sophisticated means to convey a realistic, kinesthetic impression of size, resistance or inertia. We present the concept and implementation of Drag:on, an ungrounded shape-changing VR controller that provides dynamic passive haptic feedback based on drag, i.e. air resistance, and weight shift. Drag...

While the use of ad blockers prevents negative impacts of advertising on user experience, it poses a serious threat to the business model of commercial web services and freely available content on the web. As an alternative, we investigate the user enjoyment and the advertising effectiveness of playfully deactivating online ads. We created eight ga...

Often, online ads are disruptive and annoying. As a consequence, ad blockers are used to prevent ads from appearing on a website. However, web service providers lose more than 35 billion dollars per year because of this development. As an alternative, we investigate the user enjoyment and the advertising effectiveness of playfully deactivating onli...

Virtual Reality (VR) is more accessible than ever these days. While topics like performance, motion sickness and presence are well investigated, basic topics as VR User Interfaces (UIs) for menu control are lagging far behind. A major issue is the absence of haptic feedback and naturalness, especially when considering mid-air finger-based interacti...

In many domains, real-world processes are traditionally communicated to users through abstract graph-based models like event-driven process chains (EPCs), i.e. 2D representations on paper or desktop monitors. We propose an alternative interface to explore EPCs, called immersive process models, which aims to transform the exploration of EPCs into a...

Often, online ads are annoying. Ad blockers are a way to prevent ads from appearing on a web page. As a result, web service providers lose more than 35 billion dollars per year and freely available content on the web is at risk. Taking both interests of web service providers and users into account, we present a gamified ad blocker that allows users...

Ambient notifications are an essential element to support users in their daily activities. Designing effective and aesthetic notifications that balance the alert level while maintaining an unobtrusive dialog, require them to be seamlessly integrated into the user's environment. In an attempt to employ the living environment around us, we designed O...

In this demo, we present Slackliner 2.0, an interactive slackline training assistant which features head and skeleton tracking, and real-time feedback through life-size projection. Like in other sports, proper training leads to a faster increase of skill and lessens the risk of injuries. We chose a set of exercises from slackline literature and imp...

Sharing game control (SGC) is a multiplayer context that is considered within games user research. With the popular Twitch Plays Pokémon, settings of this type have also received broad media attention. In this paper, we introduce and describe HedgewarsSGC, our modifications to the open-source game Hedgewars to investigate different player roles in...

The motivational impact of gamification elements differs substantially across users. To account for these differences, we investigate Hexad user types and behavior change intentions as factors to personalize gamifed, persuasive fitness systems. We conducted an online study (N = 179), measuring the perceived persuasiveness of twelve gamification ele...