This paper discusses the use of gesture and non-speech audio as ways to improve the user interface of a mobile music player. Their key advantages mean that users could use a player without having to look at its controls when on the move. Two very different evaluations of the player took place: one based on a standard usability experiment (comparing the new player to a standard design) and the other a video analysis of the player in use. Both of these showed significant usability improvements for the gesture/audiobased interface over a standard visual/pen-based display. The similarities and differences in the results produced by the two studies are discussed.

When on the move, cognitive resources are reserved partly for passively monitoring and reacting to contexts and events, and partly for actively constructing them. The Resource Competition Framework (RCF), building on the Multiple Resources Theory, explains how psychosocial tasks typical of mobile situations compete for cognitive resources and then suggests that this leads to the depletion of resources for task interaction and eventually results in the breakdown of fluent interaction. RCF predictions were tested in a semi-naturalistic field study measuring attention during the performance of assigned Web search tasks on mobile phone while moving through nine varied but typical urban situations. Notably, we discovered up to eight-fold differentials between micro-level measurements of attentional resource fragmentation, for example from spans of over 16 seconds in a laboratory condition dropping to bursts of just a few seconds in difficult mobile situations. By calibrating perceptual sampling, reducing resource usage for tasks of secondary importance, and resisting the impulse to switch tasks before finalization, participants compensated for the resource depletion. The findings are compared to previous studies in office contexts. The work is valuable in many areas of HCI dealing with mobility. ACM Classification Keywords: H5.m. Information interfaces and presentation (e.g., HCI): Miscellaneous

www.dcs.gla.ac.uk/~stephen Mobile and wearable computers present input/output problems due to limited screen space and interaction techniques. When mobile, users typically focus their visual attention on navigating their environment- making visually demanding interface designs hard to operate. This paper presents two multimodal interaction techniques designed to overcome these problems and allow truly mobile, ‘eyes-free ’ device use. The first is a 3D audio radial pie menu that uses head gestures for selecting items. An evaluation of a range of different audio designs showed that egocentric sounds reduced task completion time, perceived annoyance, and allowed users to walk closer to their preferred walking speed. The second is a sonically enhanced 2D gesture recognition system for use on a belt-mounted PDA. An evaluation of the system with and without audio feedback showed users ’ gestures were more accurate when dynamically guided by audio-feedback. These novel interaction techniques demonstrate effective alternatives to visual-centric interface designs on mobile devices.

Usability evaluation of systems for mobile computers and devices is an emerging area of research. This paper presents and evaluates six techniques for evaluating the usability of mobile computer systems in laboratory settings. The purpose of these techniques is to facilitate systematic data collection in a controlled environment and support the identification of usability problems that are experienced in mobile use. The proposed techniques involve various aspects of physical motion combined with either needs for navigation in physical space or division of attention. The six techniques are evaluated through two usability experiments where walking in a pedestrian street was used as a reference. Each of the proposed techniques had some similarities to testing in the pedestrian street, but none of them turned out to be completely comparable to that form of field-evaluation. Seating the test subjects at a table supported identification of significantly more usability problems than any of the other proposed techniques. However a large number of the additional problems identified using this technique were categorized as cosmetic. When increasing the amount of physical activity, the test subjects also experienced a significantly increased subjective workload. 1.

We have implemented and tested a PDA-based system that gives a shopper directions through a shopping mall on the basis of (a) the types of products that the shopper has expressed an interest in, (b) the shopper's current location, and (c) the purchases that the shopper has made so far. The system uses decision-theoretic planning to compute a policy that optimizes the expected utility of a shopper's walk through the shopping mall, taking into account uncertainty about (a) whether the shopper will actually find a suitable product in a given location and (b) the time required for each purchase. To assess the acceptability of this approach to potential users, on two floors of a building we constructed a mock-up of a shopping mall with 15 stores. Each of 20 subjects in our study shopped twice in the mall, once using our system and once using a paper map. The subjects completed their tasks significantly more effectively using the PDA-based shopping guide, and they showed a clear preference for it. They also yielded numerous specific ideas about the conditions under which the guide will be useful and about ways of increasing its usability.

This paper presents a mobile audio space intended for use by gelled social groups. In face-to-face interactions in such social groups, conversational floors change frequently, e.g., two participants split off to form a new conversational floor, a participant moves from one conversational floor to another, etc. To date, audio spaces have provided little support for such dynamic regroupings of participants, either requiring that the participants explicitly specify with whom they wish to talk or simply presenting all participants as though they are in a single floor. By contrast, the audio space described here monitors participant behavior to identify conversational floors as they emerge. The system dynamically modifies the audio delivered to each participant to enhance the salience of the participants with whom they are currently conversing. We report a user study of the system, focusing on conversation analytic results.

Desktop user interface design originates from the fact that users are stationary and can devote all of their visual resource to the application with which they are interacting. In contrast, users of mobile and wearable devices are typically in motion whilst using their device which means that they cannot devote all or any of their visual resource to interaction with the mobile application – it must remain with the primary task, often for safety reasons. Additionally, such devices have limited screen real estate and traditional input and output capabilities are generally restricted. Consequently, if we are to develop effective applications for use on mobile or wearable technology, we must embrace a paradigm shift with respect to the interaction techniques we employ for communication with such devices. This paper discusses why it is necessary to embrace a paradigm shift in terms of interaction techniques for mobile technology and presents two novel multimodal interaction techniques which are effective alternatives to traditional, visual-centric interface designs on mobile devices as empirical examples of the potential to achieve this shift. 1

baudisch @ microsoft.com Figure 1. Using earPod. (a, b) Sliding the thumb on the circular touchpad allows discovery of menu items; (c) the desired item is selected by lifting the thumb; (d) faster finger motions cause partial playback of audio. Size of the touchpad has been exaggerated for illustration purposes. We present the design and evaluation of earPod: an eyesfree menu technique using touch input and reactive auditory feedback. Studies comparing earPod with an iPod-like visual menu technique on reasonably-sized static menus indicate that they are comparable in accuracy. In terms of efficiency (speed), earPod is initially slower, but outperforms the visual technique within 30 minutes of practice. Our results indicate that earPod is potentially a reasonable eyesfree menu technique for general use, and is a particularly exciting technique for use in mobile device interfaces. ACM Classification: H5.2 [Information interfaces and presentation]: User Interfaces. Input devices and strategies;

In this paper we describe an experiment investigating the ability of participants to identify multiple, concurrently playing structured sounds, called earcons. Several different sets of earcons were compared, one "state of the art" set based on the guidelines of Brewster [1], and other sets of earcons modified to take account of auditory scene analysis principles. The effect of the number of concurrently playing earcons on identification was also investigated, with instances of 1, 2, 3 and 4 concurrently playing earcons tested. Overall, performance was low, with less than two earcons being successfully identified in any condition. However it was found that both staggering the onset times of each earcon, as well as presenting each earcon with a unique timbre, had a significantly positive effect on identification.

When designing a usability evaluation, choices must be made regarding methods and techniques for data collection and analysis. Mobile guides raise new concerns and challenges to established usability evaluation approaches. Not only are they typically closely related to objects and activities in the user’s immediate surroundings, they are often used while the user is ambulating. This paper presents results from an extensive, multi-method evaluation of a mobile guide designed to support the use of public transport in Melbourne, Australia. In evaluating the guide, we applied four different techniques; field-evaluation, laboratory evaluation, heuristic walkthrough and rapid reflection. This paper describes these four approaches and their respective outcomes, and discusses their relative strengths and weaknesses for evaluating the usability of mobile guides.