Publikationen von Benjamin Simon

On the skin, a small distance between two actuators can result in the perception of a single, centralized stimulus rather than two distinct stimuli – this phenomenon is known as the funneling illusion. In this work, we explore the electrotactile funneling illusion on the forearm in a user study with 16 participants. We placed an electrode strip with 9 electrode pairs along their forearm – from wrist to elbow. The calibration of the same perceived intensity of each electrode pair for each participant shows that the calibrated intensities near the wrist are significantly higher compared to the intensities calibrated near the elbow. A linear regression corresponds to this behavior as well as the qualitative feedback of our participants. Based on this, we created an equation that helps to reduce the calibration time considerably. The results of our study show that the funneling illusion can be reliably evoked at distances of up to 7.2cm. Further, we provide detailed information on occurrence frequency and precision and explored whether an approach adapted for electrotactile feedback can create an apparent tactile motion.

Operating small touchscreens with the finger occludes a large part of the screen. We propose using the watch case as the input space, without enlarging the smartwatch. Therefore, we created two prototypes, one with a touch surface on the watch case (CASE) and one with touch surfaces on the watch case and the wristband (CASE+BAND). In a comparative study, we analyze their suitability in a 1D list scrolling task and 2D map navigation task. The results show that occlusion is less of a problem for the list scrolling task, as visibility is sufficient. In the map navigation task, participants reached task completion times with CASE+BAND that are comparable to touch input. CASE was significantly slower, but only requires minimal additional hardware. However, the results of a subsequent longitudinal study demonstrates the learnability of CASE, which led to task completion times comparable to touch input, and provides insights in the gradual development of expert performance.

Cycling navigation is a complex and stressful task as the cyclist needs to focus simultaneously on the navigation, the road, and other road users. We propose directional electrotactile feedback at the wrist to reduce the auditory and visual load during navigation-aided cycling. We designed a custom electrotactile grid with 9 electrodes that is clipped under a smartwatch. In a preliminary study we identified suitable calibration settings and gained first insights about a suitable electrode layout. In a subsequent laboratory study we showed that a direction can be encoded with a mean error of 19.28° (σ = 42.77°) by combining 2 adjacent electrodes. Additionally, by interpolating with 3 electrodes a direction can be conveyed with a similar mean error of 22.54° (σ = 43.57°). We evaluated our concept of directional electrotactile feedback for cyclists in an outdoor study, in which 98.8% of all junctions were taken correctly by eight study participants. Only one participant deviated substantially from the optimal path, but was successfully navigated back to the original route by our system.

Prior research has designed and evaluated Voice Assistance (VA) for different settings such as the home, school, and public spaces. Office environments have been relatively understudied, leaving a gap in understanding the essential factors for designing a VA specifically for work settings. In this study, we developed the WorkFit VA specific for the office environment, focusing on the health and well-being of knowledge workers. WorkFit was designed to monitor knowledge workers for sedentary behavior, inconsistent hydration, and stress, and to deliver proactive voice interventions followed by a health recommendation to mitigate those issues. We evaluated WorkFit in a field study with 15 knowledge workers for 5 working days. In the study, we determined challenges and opportunities for voice interactions in work settings. We identified contextual factors for identifying inopportune moments for voice interactions in an office setting. We found that 92\% of knowledge workers accepted WorkFit’s hydration interventions while 79\% of them engaged in walking breaks. Moreover, breathing exercises recommended by WorkFit significantly stabilized the heart rate of knowledge workers during stress. Based on our findings, we propose five design recommendations for the development of VA customized to office settings.

Recent research in Human-Computer Interaction for work has shown that conversational agents (CA) are beneficial for supporting focused work and well-being while at work. Knowledge workers struggle in maintaining focus, work schedule, and well-being. Typically, they rely on multiple tools and services for work productivity, scheduling tasks, and reminding breaks. With the goal of tackling these problems, we propose the concept of a ubiquitous work assistant (UWA), which consists of two components: a stationary CA (S-CA) and a wearable CA (W-CA). S-CA is meant to be placed on user’s work desk while W-CA is fixed on the user’s wrist. The UWA interface is distributed between S-CA and W-CA. We initiated our study by conducting semi-structured interviews with knowledge workers (N = 14). We identified their expectations from conversational agents (CAs) that would assist them in their daily work life. From the interview findings, we developed an UWA prototype that could assist users by briefing their daily schedule, monitoring their schedule, and reminding breaks. We conducted a lab study simulating a home-office environment. The findings of the study show that the knowledge workers see potential in the UWA system. Further, we discuss implications of distributed user interface (DUI) for UWA design.

Tactile patterns are a means to convey navigation instructions to pedestrians and are especially helpful for people with visual impairments. This article presents a concept to provide precise micro-navigation instructions through a tactile around-the-head display. Our system presents four tactile patterns for fundamental navigation instructions in conjunction with continuous directional guidance. We followed an iterative, user-centric approach to design the patterns for the fundamental navigation instructions, combined them with a continuous directional guidance stimulus, and tested our system with 13 sighted (blindfolded) and 2 blind participants in an obstacle course, including stairs. We optimized the patterns and validated the final prototype with another five blind participants in a follow-up study. The system steered our participants successfully with a 5.7 cm average absolute deviation from the optimal path. Our guidance is only a little less precise than the usual shoulder wobbling during normal walking and an order of magnitude more precise than previous tactile navigation systems. Our system allows various new use cases of micro-navigation for people with visual impairments, e.g., preventing collisions on a sidewalk or as an anti-veering tool. It also has applications in other areas, such as personnel working in low-vision environments (e.g., firefighters).

Creating tactile patterns on the body via a spatial arrangement of many tactile actuators offers many opportunities and presents a challenge, as the design space is enormous. This paper presents a VR interface that enables designers to rapidly prototype complex tactile interfaces. It allows for painting strokes on a modeled body part and translates these strokes into continuous tactile patterns using an interpolation algorithm. The presented VR approach avoids several problems of traditional 2D editors. It realizes spatial 3D input using VR controllers with natural mapping and intuitive spatial movements. To evaluate this approach in detail, we conducted a user study and iteratively improved the system. The study participants gave predominantly positive feedback on the presented VR interface (SUS score 79.7, AttrakDiff “desirable”). The final system is released alongside this paper as an open-source Unity project for various tactile hardware.

The vibrotactile funneling illusion is the sensation of a single (non-existing) stimulus somewhere in-between the actual stimulus locations. Its occurrence depends upon body location, distance between the actuators, signal synchronization, and intensity. Related work has shown that the funneling illusion may occur on the forehead. We were able to reproduce these findings and explored five further regions to get a more complete picture of the occurrence of the funneling illusion on the head. The results of our study (24 participants) show that the actuator distance, for which the funneling illusion occurs, strongly depends upon the head region. Moreover, we evaluated the centralizing bias (smaller perceived than actual actuator distances) for different head regions, which also showed widely varying characteristics. We computed a detailed heat map of vibrotactile localization accuracies on the head. The results inform the design of future tactile head-mounted displays that aim to support the funneling illusion.