Zur Person:

Jonas Keppel ist wissenschaftlicher Mitarbeiter der Arbeitsgruppe Mensch-Computer Interaktion an der Universität Duisburg-Essen. Im Bachelor studierte er Mathematik an der Universität Duisburg-Essen und arbeitete während des Studiums als studentische Hilfskraft, wobei er Lehrerfahrung als Übungsleiter und Korrektor sammelte. Zudem wurde er mehrfach mit dem Deutschlandstipendium der UDE ausgezeichnet. Seinen Masterabschluss in Technomathematik mit Anwendungsfach Informatik legte Jonas ebenfalls an der Universität Duisburg-Essen ab, wobei er seine Masterarbeit in Kooperation zwischen Mathematik und Informatik über ein Visualisierungstool zur Verteidigung von Angriffen auf Deep Learning Modelle schrieb. Momentan forscht er auch im Bereich der Mensch-Computer Interaktion und wirkt bei dem Projekt "Erweiterte Gesundheitsintelligenz für persönliche Verhaltensstrategien im Alltag" (Eghi) mit.

Forschungsgebiete:

Jonas Keppel auf Google Scholar und ResearchGate

Publikationen:

• Keppel, Jonas; Strauss, Marvin; Haliburton, Luke; Weingärtner, Henrike; Dominiak, Julia; Faltaous, Sarah; Gruenefeld, Uwe; Mayer, Sven; Woźniak, Paweł W.; Schneegass, Stefan: Situated Artifacts Amplify Engagement in Physical Activity. In: Proceedings of the 2025 ACM Designing Interactive Systems Conference, Jg. 2025 (2025). doi:10.1145/3715336.3735690VolltextBIB DownloadKurzfassungDetails

  In the context of rising sedentary lifestyles, this paper investigates the efficacy of “Situated Artifacts” in promoting physical activity. We designed two artifacts that display users’ physical activity data within their homes – one physical and one digital. We conducted a 9-week, counterbalanced, within-subject field study with N = 24 participants to assess the impact of these artifacts on physical activity, reflection, and motivation. We collected quantitative data on physical activity and administered daily and weekly questionnaires, employing individual Likert items and standardized instruments, as well as conducted interviews post-prototype usage. Our findings indicate that while both artifacts act as reminders for physical activity, the physical artifact was superior in terms of user engagement. The study revealed that this can be attributed to the higher perceived presence and, thereby, enhanced social interaction, which acts as a motivational source for activity. In this sense, situated artifacts gently nudge toward sustainable health behavior change.

• Keppel, Jonas; Strauss, Marvin; Zhang, Shuoheng; Stroehnisch, Markus; Lewin, Stefan; Gruenefeld, Uwe; Degraen, Donald; Goedicke, David; Matviienko, Andrii; Schneegass, Stefan: The Impact of Bike-Based Controllers and Adaptive Feedback on Immersion and Enjoyment in a Virtual Reality Cycling Exergame. In: Proceedings of the Extended Abstracts of the CHI Conference on Human Factors in Computing Systems. Association for Computing Machinery, New York, NY, USA 2025. doi:10.1145/3706599.3720096VolltextBIB DownloadKurzfassungDetails

  Cycling exergames can increase enjoyment and promote high energy expenditure, making exercise more engaging and, therefore, supporting healthier lifestyles. To improve player experience in a virtual reality cycling exergame using a stationary bike, we investigated how different input and output techniques affect player engagement. We implemented a bike-based controller integrating button and shoulder-lean steering as input, combined with or without adaptive changes in bike inclination and resistance as output. The results of our study with 24 participants indicate that adaptive modes increase effort and perceived exertion. While button steering provides better pragmatic quality, shoulder-lean steering offers a more hedonic experience but requires more skill and effort. Still, this greater enjoyment fosters higher engagement, particularly when players enter a flow state where the increased physical demands become less noticeable. These findings underscore the potential of bike-based adaptive controllers to maximize player engagement and enhance VR cycling exergame experiences.

• Wald, Iddo Yehoshua; Degraen, Donald; Maimon, Amber; Keppel, Jonas; Schneegass, Stefan; Malaka, Rainer: Demonstrating Spatial Haptics: A Sensory Substitution Method for Distal Object Detection Using Tactile Cues. In: Proceedings of the Extended Abstracts of the CHI Conference on Human Factors in Computing Systems. Association for Computing Machinery, New York, NY, USA 2025. doi:10.1145/3706599.3721281BIB DownloadKurzfassungDetails

  We present Spatial Haptics, a sensory substitution method for representing locations of remote objects in 3D space via haptics. Spatial Haptics imitates auditory localization processes to enable vibrotactile localization abilities similar to those of some animal species. Two implementations of the localization method were developed, that modulate the vibration amplitude of the controllers relative to a target object in Virtual Reality. In Ear-Based Localization, vibrations are modulated based on the relative locations of the ears to the target, while in Hand-Based Localization, the amplitude is determined based on the relative locations of the hands to the target. In this interactive demonstration, users can experience the vibrotactile localization approaches in an interactive VR mini-game. Their task is to locate the target object in a scene consisting of multiple moving objects. By experiencing spatial localization using haptics hands-on, participants can evaluate the benefits of this sensory substitution approach for detecting distal objects.

• Wald, Iddo Yehoshua; Degraen⁎, Donald; Maimon⁎, Amber; Keppel, Jonas; Schneegass, Stefan; Malaka, Rainer: Spatial Haptics: A Sensory Substitution Method for Distal Object Detection Using Tactile Cues. In: Proceedings of the 2025 CHI Conference on Human Factors in Computing Systems. Association for Computing Machinery, New York, NY, USA 2025. doi:10.1145/3706598.3714083BIB DownloadKurzfassungDetails

  We present a sensory substitution-based method for representing locations of remote objects in 3D space via haptics. By imitating auditory localization processes, we enable vibrotactile localization abilities similar to those of some spiders, elephants, and other species. We evaluated this concept in virtual reality by modulating the vibration amplitude of two controllers depending on relative locations to a target. We developed two implementations applying this method using either ear or hand locations. A proof-of-concept study assessed localization performance and user experience, achieving under 30° differentiation between horizontal targets with no prior training. This unique approach enables localization by using only two actuators, requires low computational power, and could potentially assist users in gaining spatial awareness in challenging environments. We compare the implementations and discuss the use of hands as ears in motion, a novel technique not previously explored in the sensory substitution literature.

• Keppel, Jonas; Strauss, Marvin; Gruenefeld, Uwe; Schneegass, Stefan: Magic Mirror: Designing a Weight Change Visualization for Domestic Use. In: Proc. ACM Hum.-Comput. Interact., Jg. 8 (2024). doi:10.1145/3698149BIB DownloadKurzfassungDetails

  Virtual mirrors displaying weight changes can support users in forming healthier habits by visualizing potential future body shapes. However, these often come with privacy, feasibility, and cost limitations. This paper introduces the Magic Mirror, a novel distortion-based mirror that leverages curvature effects to alter the appearance of body size while preserving privacy. We constructed the Magic Mirror and compared it to a video-based alternative. In an online study (N=115), we determined the optimal parameters for each system, comparing weight change visualizations and manipulation levels. Afterward, we conducted a laboratory study (N=24) to compare the two systems in terms of user perception, motivational potential, and willingness to use daily. Our findings indicate that the Magic Mirror surpasses the video-based mirror in terms of suitability for residential application, as it addresses feasibility concerns commonly associated with virtual mirrors. Our work demonstrates that mirrors that display weight changes can be implemented in users’ homes without any cameras, ensuring privacy.

• Keppel, Jonas; Schneegass, Stefan: Buying vs. Building: Can Money Fix Everything When Prototyping in CyclingHCI for Sports?, CHI 2024, Honolulu, Hawai'i 2024. PDFVolltextBIB DownloadKurzfassungDetails

  This position paper explores the dichotomy of building versus buying in the domain of Cycling Human-Computer Interaction (CyclingHCI) for sports applications. Our research focuses on indoor cycling to enhance physical activity through sports motivation. Recognizing that the social component is crucial for many users to sustain regular sports engagement, we investigate the integration of social elements within indoor cycling topics. We outline two approaches: First, we utilize Virtual Reality (VR) Exergames using a bike-based controller as input and actuator aiming for immersive experiences and, therefore, buying a commercial smartbike, the Wahoo KickR Bike. Second, we enhance traditional spinning classes with interactive technology to foster social components during courses, building self-made sensors for attachment to mechanical indoor bikes. Finally, we discuss the challenges and benefits of constructing custom sensors versus purchasing commercial bike trainers. Our lessons learned contribute to informed decision-making in CyclingHCI prototyping, balancing innovation with practicality.

• Ivezić, Dijana; Keppel, Jonas; Horneber, David; Becker, Christine; Laumer, Sven; Walle, Hardy; Schneegass, Stefan; Amft, Oliver: EghiFit: Smartphone based Behaviour Monitoring and Health Recommendation in a Weight Loss Intervention Study. In: F1000Research, Jg. 13 (2024), S. 1347. VolltextBIB DownloadDetails
• Keppel, Jonas; Ivezić, Dijana; Gruenefeld, Uwe; Lukowicz, Paul; Amft, Oliver; Schneegass, Stefan: AI and Health: Using Digital Twins to Foster Healthy Behavior. In: Mensch und Computer 2024-Workshopband. 2024, S. 10-18420. doi:10.18420/muc2024-mci-ws05-114VolltextBIB DownloadDetails
• Ivezić, Dijana; Keppel, Jonas; Schneegass, Stefan; Amft, Oliver: Patient Adherence and Challenges in a Weight Loss Study: Smartphone Data Stream and Gamification, Gesellschaft für Informatik e.V., 2024. doi:10.18420/muc2024-mci-ws05-222) BIB DownloadKurzfassungDetails

  This paper presents findings from our implementation of a context aware health guidance system for obese individuals, with a focus on smartphone- and smartwatch-based health monitoring and participant adherence. To aid participants in weight loss, our system utilizes data from wearables and smartphones, integrating nutrition tracking and gamification elements into a smartphone application and a web-based health dashboard for health coaches. Eight participants completed a 120-day field study to evaluate the system and examine user adherence to health monitoring and the effectiveness of gamification in a weight loss program. Data on steps, sleep, heart rate, weather, and manually logged meals were collected. Adherence varied across data types, with step counts being the most consistently collected, while sleep and heart rate data were limited due to inconsistent smartwatch usage.

• Faltaous, Sarah; Williamson, Julie R.; Koelle, Marion; Pfeiffer, Max; Keppel, Jonas; Schneegass, Stefan: Understanding User Acceptance of Electrical Muscle Stimulation in Human-Computer Interaction. In: Proceedings of the 2024 CHI Conference on Human Factors in Computing Systems. Association for Computing Machinery, New York, NY, USA 2024. doi:10.1145/3613904.3642585BIB DownloadKurzfassungDetails

  Electrical Muscle Stimulation (EMS) has unique capabilities that can manipulate users’ actions or perceptions, such as actuating user movement while walking, changing the perceived texture of food, and guiding movements for a user learning an instrument. These applications highlight the potential utility of EMS, but such benefits may be lost if users reject EMS. To investigate user acceptance of EMS, we conducted an online survey (N = 101). We compared eight scenarios, six from HCI research applications and two from the sports and health domain. To gain further insights, we conducted in-depth interviews with a subset of the survey respondents (N = 10). The results point to the challenges and potential of EMS regarding social and technological acceptance, showing that there is greater acceptance of applications that manipulate action than those that manipulate perception. The interviews revealed safety concerns and user expectations for the design and functionality of future EMS applications.

• Keppel, Jonas; Strauss, Marvin; Faltaous, Sarah; Liebers, Jonathan; Heger, Roman; Gruenefeld, Uwe; Schneegass, Stefan: Don't Forget to Disinfect: Understanding Technology-Supported Hand Disinfection Stations. In: Proc. ACM Hum.-Comput. Interact., Jg. 7 (2023). doi:10.1145/3604251PDFBIB DownloadKurzfassungDetails

  

  The global COVID-19 pandemic created a constant need for hand disinfection. While it is still essential, disinfection use is declining with the decrease in perceived personal risk (e.g., as a result of vaccination). Thus this work explores using different visual cues to act as reminders for hand disinfection. We investigated different public display designs using (1) paper-based only, adding (2) screen-based, or (3) projection-based visual cues. To gain insights into these designs, we conducted semi-structured interviews with passersby (N=30). Our results show that the screen- and projection-based conditions were perceived as more engaging. Furthermore, we conclude that the disinfection process consists of four steps that can be supported: drawing attention to the disinfection station, supporting the (subconscious) understanding of the interaction, motivating hand disinfection, and performing the action itself. We conclude with design implications for technology-supported disinfection.

• Keppel, Jonas; Gruenefeld, Uwe; Strauss, Marvin; Gonzalez, Luis Ignacio Lopera; Amft, Oliver; Schneegass, Stefan: Reflecting on Approaches to Monitor User's Dietary Intake, MobileHCI 2022, Vancouver, Canada 2022. PDFVolltextBIB DownloadKurzfassungDetails

  Monitoring dietary intake is essential to providing user feedback and achieving a healthier lifestyle. In the past, different approaches for monitoring dietary behavior have been proposed. In this position paper, we first present an overview of the state-of-the-art techniques grouped by image- and sensor-based approaches. After that, we introduce a case study in which we present a Wizard-of-Oz approach as an alternative and non-automatic monitoring method.

• Keppel, Jonas; Öztürk, Alper; Herbst, Jean-Luc; Lewin, Stefan: Artificial Conscience - Fight the Inner Couch Potato, MobileHCI 2022, Vancouver, Canada 2022. PDFVolltextBIB DownloadKurzfassungDetails

  The Artificial Conscience concept aims to improve the user’s quality of life by giving recommendations for a healthier lifestyle and reacting to possibly harmful situations detected by the various sensors of the Huawei Eyewear. But autonomous reactions to situations that pose an immediate danger to the user’s health as well as methods for habit-forming and other supporting functions are only representing a subset of the possible design space. All functions of this concept are described and evaluated individually, both under the assumption of autonomous operation of the Huawei Eyewear and with the inclusion of other data sources and sensors (smartphone, smartwatch). In addition, an outlook is given on additional features for the Huawei Eyewear that could be implemented in future versions of the glasses. YouTube

• Detjen, Henrik; Faltaous, Sarah; Keppel, Jonas; Prochazka, Marvin; Gruenefeld, Uwe; Sadeghian, Shadan; Schneegass, Stefan: Investigating the Influence of Gaze- and Context-Adaptive Head-up Displays on Take-Over Requests. In: Acm (Hrsg.): AutomotiveUI '22: Proceedings of the 14th International Conference on Automotive User Interfaces and Interactive Vehicular Applications. 2022. doi:10.1145/3543174.3546089VolltextBIB DownloadKurzfassungDetails

  In Level 3 automated vehicles, preparing drivers for take-over requests (TORs) on the head-up display (HUD) requires their repeated attention. Visually salient HUD elements can distract attention from potentially critical parts in a driving scene during a TOR. Further, attention is (a) meanwhile needed for non-driving-related activities and can (b) be over-requested. In this paper, we conduct a driving simulator study (N=12), varying required attention by HUD warning presence (absent vs. constant vs. TOR-only) across gaze-adaptivity (with vs. without) to fit warnings to the situation. We found that (1) drivers value visual support during TORs, (2) gaze-adaptive scene complexity reduction works but creates a benefit-neutralizing distraction for some, and (3) drivers perceive constant HUD warnings as annoying and distracting over time. Our findings highlight the need for (a) HUD adaptation based on user activities and potential TORs and (b) sparse use of warning cues in future HUD designs.

• Faltaous, Sarah; Prochazka, Marvin; Auda, Jonas; Keppel, Jonas; Wittig, Nick; Gruenefeld, Uwe; Schneegass, Stefan: Give Weight to VR: Manipulating Users’ Perception of Weight in Virtual Reality with Electric Muscle Stimulation, Association for Computing Machinery, New York, NY, USA 2022. (ISBN 9781450396905) doi:10.1145/3543758.3547571) BIB DownloadKurzfassungDetails

  Virtual Reality (VR) devices empower users to experience virtual worlds through rich visual and auditory sensations. However, believable haptic feedback that communicates the physical properties of virtual objects, such as their weight, is still unsolved in VR. The current trend towards hand tracking-based interactions, neglecting the typical controllers, further amplifies this problem. Hence, in this work, we investigate the combination of passive haptics and electric muscle stimulation to manipulate users’ perception of weight, and thus, simulate objects with different weights. In a laboratory user study, we investigate four differing electrode placements, stimulating different muscles, to determine which muscle results in the most potent perception of weight with the highest comfort. We found that actuating the biceps brachii or the triceps brachii muscles increased the weight perception of the users. Our findings lay the foundation for future investigations on weight perception in VR.

• Keppel, Jonas; Liebers, Jonathan; Auda, Jonas; Gruenefeld, Uwe; Schneegass, Stefan: ExplAInable Pixels: Investigating One-Pixel Attacks on Deep Learning Models with Explainable Visualizations. In: Proceedings of the 21st International Conference on Mobile and Ubiquitous Multimedia. Association for Computing Machinery, New York, NY, USA 2022, S. 231-242. doi:10.1145/3568444.3568469BIB DownloadKurzfassungDetails

  Nowadays, deep learning models enable numerous safety-critical applications, such as biometric authentication, medical diagnosis support, and self-driving cars. However, previous studies have frequently demonstrated that these models are attackable through slight modifications of their inputs, so-called adversarial attacks. Hence, researchers proposed investigating examples of these attacks with explainable artificial intelligence to understand them better. In this line, we developed an expert tool to explore adversarial attacks and defenses against them. To demonstrate the capabilities of our visualization tool, we worked with the publicly available CIFAR-10 dataset and generated one-pixel attacks. After that, we conducted an online evaluation with 16 experts. We found that our tool is usable and practical, providing evidence that it can support understanding, explaining, and preventing adversarial examples.