Patrick Bader

A smartphone prototype for touch interaction on the whole device surface

Previous research proposed a wide range of interaction methods and use cases based on the previously unused back side and edge of a smartphone. Common approaches to implementing Back-of-Device (BoD) interaction include attaching two smartphones back to back and building a prototype completely from scratch. Changes in the devices form factor can influence hand grip and input performance as shown in previous work. Further, the lack of an established operating system and SDK requires more effort to implement novel interaction methods. In this work, we present a smartphone prototype that runs Android and has a form factor nearly identical to an off-the-shelf smartphone. It further provides capacitive images of the hand holding the device for use cases such as grip-pattern recognition. We describe technical details and share source files so that others can re-build our prototype. We evaluated the prototype with 8 participants to demonstrate the data that can be retrieved for an exemplary grip classification.

Investigating Screen Shifting Techniques to Improve One-Handed Smartphone Usage

With increasingly large smartphones, it becomes more difficult to use these devices one-handed. Due to a large touchscreen, users can not reach across the whole screen using their thumb. In this paper, we investigate approaches to move the screen content in order to increase the reachability during one-handed use of large smartphones. In a first study, we compare three approaches based on back-of-device (BoD) interaction to move the screen content. We compare the most preferred BoD approach with direct touch on the front and Apples Reachability feature. We show that direct touch enables faster target selection than the other approaches but does not allow to interact with large parts of the screen. While Reachability is faster compared to a BoD screen shift method, only the BoD approach makes the whole front screen accessible.

Design and evaluation of a layered handheld 3d display with touch-sensitive front and back

Touch screens became truly pervasive through the success of smartphones and tablet PCs. Several approaches to further improve the interaction with touch screens have been proposed. In this paper we combine and extend two of these trends. We present a mobile 3D screen that consists of a stack of displays and is touch sensitive on both display sides. This design makes the screen independent from the users view angle. Using a touch-sensitive back enables back-of-device interaction to avoid the fat-finger problem. Combining back-of-device interaction with a transparent display also avoids occlusion of the users finger on the back through the device. Through a study we investigate how back and front touch improves interaction with 3D content and show how back-of-device interaction is improved if the user can actually see the finger on the back.

Interaction Methods and Use Cases for a Full-Touch Sensing Smartphone

Touchscreens are successful in recent smartphones due to a combination of input and output in a single interface. Despite their advantages, touch input still suffers from common limitations such as the fat-finger problem. To address these limitations, prior work proposed a variety of interaction techniques based on input sensors beyond the touchscreen. These were evaluated from a technical perspective. In contrast, we envision a smartphone that senses touch input on the whole device. Through interviews with experienced interaction designers, we elicited interaction methods to address touch input limitations from a different perspective. In this work, we focus on the interview results and present a smartphone prototype which senses touch input on the whole device. It has dimensions similar to regular phones and can be used to evaluate presented findings under realistic conditions in future work.

PalmTouch: Using the Palm as an Additional Input Modality on Commodity Smartphones

Touchscreens are the most successful input method for smartphones. Despite their flexibility, touch input is limited to the location of taps and gestures. We present PalmTouch, an additional input modality that differentiates between touches of fingers and the palm. Touching the display with the palm can be a natural gesture since moving the thumb towards the devices top edge implicitly places the palm on the touchscreen. We present different use cases for PalmTouch, including the use as a shortcut and for improving reachability. To evaluate these use cases, we have developed a model that differentiates between finger and palm touch with an accuracy of 99.53% in realistic scenarios. Results of the evaluation show that participants perceive the input modality as intuitive and natural to perform. Moreover, they appreciate PalmTouch as an easy and fast solution to address the reachability issue during one-handed smartphone interaction compared to thumb stretching or grip changes.

Fingers' Range and Comfortable Area for One-Handed Smartphone Interaction Beyond the Touchscreen

Previous research and recent smartphone development presented a wide range of input controls beyond the touchscreen. Fingerprint scanners, silent switches, and Back-of-Device (BoD) touch panels offer additional ways to perform input. However, with the increasing amount of input controls on the device, unintentional input or limited reachability can hinder interaction. In a one-handed scenario, we conducted a study to investigate the areas that can be reached without losing grip stability (comfortable area), and with stretched fingers (maximum range) using four different phone sizes. We describe the characteristics of the comfortable area and maximum range for different phone sizes and derive four design implications for the placement of input controls to support one-handed BoD and edge interaction. Amongst others, we show that the index and middle finger are the most suited fingers for BoD interaction and that the grip shifts towards the top edge with increasing phone sizes.

Towards pressure-based feedback for non-stressful tactile notifications

Smartphones, wearables, and other mobile devices often use tactile feedback for notifying users. This feedback type proved to be beneficial since it does not occupy the visual or auditory channel. However, it still can be distracting in other situations such as when users are already stressed. To investigate tactile feedback patterns which do not increase the users stress level, we developed two wrist-worn prototypes capable of providing tactile feedback (i.e., vibrotactile and pressure-based feedback). Further, we conducted a user-study with 14 participants comparing both feedback types. The results suggest that vibrotactile feedback increases the users stress level more, compared to pressure-based feedback particularly applied when the user currently has a low stress level. Consequently, we present implications for designing notifications for mobile and wearable devices.

The Effect of Focus Cues on Separation of Information Layers

Our eyes use multiple cues to perceive depth. Current 3D displays do not support all depth cues humans can perceive. While they support binocular disparity and convergence, no commercially available 3D display supports focus cues. To use them requires accommodation, i.e. stretching the eye lens when focusing on an individual distance. Previous work proposed multilayer and light field displays that require the eye to accommodate. Such displays enable the user to focus on different depths and blur out content that is out of focus. Thereby, they might ease the separation of content displayed on different depth layers. In this paper we investigate the effect of focus cues by comparing 3D shutter glasses with a multilayer display. We show that recognizing content displayed on a multilayer display takes less time and results in fewer errors compared to shutter glasses. We further show that separating overlapping content on multilayer displays again takes less time, results in fewer errors, and is less demanding. Hence, we argue that multilayer displays are superior to standard 3D displays if layered 3D content is displayed, and they have the potential to extend the design space of standard GUI.

Self-Actuated Displays for Vertical Surfaces

Most current devices are passive regarding their locations by being integrated in the environment or require to be carried when used in mobile scenarios. In this paper we present a novel type of self-actuated devices, which can be placed on vertical surfaces like whiteboards or walls. This enables vertical tangible interaction as well as the device interacting with the user through self-actuated movements. In this paper, we explore the application space for such devices by aggregating user-defined application ideas gathered in focus groups. Moreover, we implement and evaluate four interaction scenarios, discuss their usability and identify promising future use cases and improvements.

Towards Interaction Techniques for Social Media Data Exploration on Large High-Resolution Displays

Exploring large geolocated social media datasets is now an important task in many pursuits e.g. crisis response. Yet there is still a lack of effective methods to view and interact with large amounts spatially-disturbed user-generated content. In this work, we explore interaction techniques for an extended version of ScatterBlogs - an interactive application for exploring massive twitter datasets on large high-resolution displays. We designed an interaction technique that employs multiple tablets to enable multiple users to effectively manipulate geolocated twitter massages on a large screen. In a preliminary user study, we compared our technique with using a desktop computer. Results indicate that the technique offers superior performance and user experience. In future work, we will explore how our technique can enhance the user experience of interacting with analytics applications.