Far beyond very fine-grained, accurate data, movement-based interaction design often benefits from working with higher-level features to create engaging interactions. Yet, movement-based frameworks most often focus on the detection strategy without providing clarity on how to use such data for the design of user interactions. This purely technical approach makes it challenging for practitioners to explore feature extraction technology as a design material. This paper presents an approach that considers designers’ perspectives and attitudes about using movement-based features to propose a set of designer-interpretable descriptors and enhance their ability to use human motion in interaction design. In addition, a computational prototype is utilized to visually present the features and help designers better understand movement content. The investigation into the effects of designer-interpretable features on the concept ideation and design of motion-based interactions followed a user-centered approach, and its validity was established through a qualitative study conducted with interaction designers. Semi-structured interviews following a creative practice exercise were employed to evaluate how the computational prototype influenced interaction designers’ processes, allowing them to reflect on their experience and compare it to previous approaches when designing movement-based interactions. The study determined that interaction designers were able to leverage features to identify detection capabilities and enrich the ideation process. Moreover, feature visualization provided further insights into the characteristics of movement, which helped practitioners understand the interaction opportunities that come with it. • Designer-interpretable features enable non-technical practitioners to use motion analysis. • Spatial visualizations make group detection accessible without algorithmic expertise. • Five themes reveal how accessible features transform installation design practice. • Designers prioritize spatial patterns over biomechanical precision for public spaces. • Evidence-based iteration replaces technology-constrained design in motion systems.

InTangible is a mixed media artwork and connected object that captures images of a handwoven fabric and sends them through the network. A digital camera with built-in RGB LEDs, configured with a combination of digital parameters, glides over the fabric and allows remote users to enjoy a new, intimate dimension of the textile. The once static and monochrome texture is transformed into colourful, abstract digital dreamscapes, while, at the same time, becomes a material object meant to be exhibited in a physical space.

We present MagicScroll, a rollable tablet with 2 concatenated flexible multitouch displays, actuated scrollwheels and gestural input. When rolled up, MagicScroll can be used as a rolodex, smartphone, expressive messaging interface or gestural controller. When extended, it provides full access to its 7.5" high-resolution multitouch display, providing the display functionality of a tablet device. We believe that the cylindrical shape in the rolled-up configuration facilitates gestural interaction, while its shape changing and input capabilities allow the navigation of continuous information streams and provide focus plus context functionality. We investigated the gestural affordances of MagicScroll in its rolled-up configuration by means of an elicitation study.

In this paper, we report on a study investigating a novel haptic illusion for altering the perception of 3D shapes using a non-planar screen and vibrotactile friction. In our study, we presented an image of a rectangular prism on a cylindrical and a flat display. Participants were asked to move their index finger horizontally along the surface of the displays towards the edge of the rectangular prism. Participants were asked whether they were experiencing a flat, cylindrical or rectangular shape. In one condition, a vibrotactile stimulus simulated increasing friction towards the visible edge of the rectangular prism, with a sudden drop-off when this edge was crossed by the finger. Results suggest that presenting an image of a rectangular prism, and applying vibrotactile friction, particularly on a cylindrical display, significantly increased participant ratings stating that they were experiencing a physical rectangular shape.

In this paper, we report on an investigation of Fitts' law using flexible displays. Participants performed a one-dimensional targeting task as described by the ISO 9421-9 standard. In the experiment, we compared two methods of bend input: position control and rate control of a cursor. Participants performed the task with three levels of device stiffness. Results show that bend input is highly correlated with Fitts' law for both position and rate control. Position control produced significantly higher throughput values than rate control. Our experiment also revealed that, when the amount of force applied was controlled, device stiffness did not have a significant effect on performance.

In this paper, we explore how shape changing interfaces might be used to communicate emotions. We present two studies, one that investigates which shapes users might create with a 2D flexible surface, and one that studies the efficacy of the resulting shapes in conveying a set of basic emotions. Results suggest that shape parameters are correlated to the positive or negative character of an emotion, while parameters related to movement are correlated with arousal level. In several cases, symbolic shape expressions based on clear visual metaphors were used. Results from our second experiment suggest participants were able to recognize emotions given a shape with a good accuracy within 28% of the dimensions of the Circumplex Model. We conclude that shape and shape changes of a 2D flexible surface indeed appear able to convey emotions in a way that is worthy of future exploration.

ReFlex is a flexible smartphone with bend input and active haptic feedback. ReFlex's features allow the introduction of sensations such as friction or resistance. We report results from an experiment using ReFlex in a targeting task, as well as initial users' reactions to the prototype. We explore both absolute and relative tactile haptic feedback, paired with two types of bend input mappings: position-control and rate-control. We observed that position-controlled cursors paired well with relative bend feedback, while rate-controlled cursors paired well with absolute bend feedback to indicate targets. We also explored an eyes-free condition. Results suggest that while eyes-free, haptic feedback conditions were more error-prone than visual-only conditions, the size of the error was relatively small, and users were able to complete the task in all cases. We present two application scenarios that take advantage of the unique input and output modalities of ReFlex and discuss its potential for within document navigation.

We present HoloFlex, a 3D flexible smartphone featuring a light-field display consisting of a high-resolution P-OLED display and an array of 16,640 microlenses. HoloFlex allows mobile users to interact with 3D images featuring natural visual cues such as motion parallax and stereoscopy without glasses or head tracking. Its flexibility allows the use of bend input for interacting with 3D objects along the z axis. Images are rendered into 12-pixel wide circular blocks-pinhole views of the 3D scene-which enable ~80 unique viewports at an effective resolution of 160 × 104. The microlens array distributes each pixel from the display in a direction that preserves the angular information of light rays in the 3D scene. We present a preliminary study evaluating the effect of bend input vs. a vertical touch screen slider on 3D docking performance. Results indicate that bend input significantly improves movement time in this task. We also present 3D applications including a 3D editor, a 3D Angry Birds game and a 3D teleconferencing system that utilize bend input.

When trying to satisfy an information need, smartphone users frequently transition from mobile search engines to mobile apps and vice versa. However, little is known about the nature of these transitions nor how mobile search and mobile apps interact. We report on a 2-week, mixed-method study involving 18 Android users, where we collected real-world mobile search and mobile app usage data alongside subjective insights on why certain interactions between apps and mobile search occur. Our results show that when people engage with mobile search they tend to interact with more mobile apps and for longer durations. We found that certain categories of apps are used more intensely alongside mobile search. Furthermore we found differences in app usage before and after mobile search and show how mobile app interactions can both prompt mobile search and enable users to take action. We conclude with a discussion on what these patterns mean for mobile search and how we might design mobile search experiences that take these app interactions into account.

We present findings of a study with 62 subjects who had 796 of their outgoing mobile phone calls recorded and transcribed for their later annotation—by highlighting important information shared during calls. We found that patterns in these calls (numbers, names, interrogative adverbs), as well as some contextual parameters, are better indicators of annotation needs than the callers' profile or call quality. Callers highlight information in both parties' turns (caller and callee) more often than highlighting solely information provided by the callee, which is mostly due to annotating questions with contextual information for the highlights in the callee's turns. We discuss how this behavior changes according to call purpose. Finally, we found that annotation needs change over time: whereas some annotations might not be considered relevant after weeks, others originally considered irrelevant might become important archival notes. We present implications of these findings for the design of mobile phone annotation tools.

Most online service providers offer free services to users and in part, these services collect and monetize personally identifiable information (PII), primarily via targeted advertisements. Against this backdrop of economic exploitation of PII, it is vital to understand the value that users put to their own PII. Although studies have tried to discover how users value their privacy, little is known about how users value their PII while browsing, or the exploitation of their PII. Extracting valuations of PII from users is non-trivial - surveys cannot be relied on as they do not gather information of the context where PII is being released, thus reducing validity of answers. In this work, we rely on refined Experience Sampling - a data collection method that probes users to valuate their PII at the time and place where it was generated in order to minimize retrospective recall and hence increase measurement validity. For obtaining an honest valuation of PII, we use a reverse second price auction. We developed a web browser plugin and had 168 users - living in Spain - install and use this plugin for 2 weeks in order to extract valuations of PII in different contexts.

Note-taking has been largely studied in contexts of work meetings. However, often people need to remember information exchanged in informal situations, such as during mobile phone conversations. In this paper we present a study conducted with 59 subjects who had their phone calls semi-automatically transcribed for later annotation. Analysis of the 621 calls and the subjects' annotation behavior revealed that phone recall is indeed a relevant user need. Furthermore, identifying patterns in phone calls such as numbers and names provide better indicators of annotation than variables related to the callers' profile, context of calls, or quality of service. Our findings suggest implications for the design of mobile phone annotation tools.