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

Abstract. Evaluating the usability of mobile systems raises new concerns and questions, challenging methods for both lab and field evaluations. A recent literature study showed that most mobile HCI research projects apply lab-based evaluations. Nevertheless, several researchers argue in favour of field evaluations as mobile systems are highly context-dependent. However, field-based usability studies are difficult to conduct, time consuming and the added value is unknown. Contributing to this discussion, this paper compares the results produced by a laboratory- and a field-based evaluation of the same context-aware mobile system on their ability to identify usability problems. Six test subjects used the mobile system in a laboratory while another six used the system in the field. The results show that the added value of conducting usability evaluations in the field is very little and that recreating central aspects of the use context in a laboratory setting enables the identification of the same usability problem list. 1

ABSTRACT * This paper describes a two-phase study conducted to determine optimal target sizes for one-handed thumb use of mobile handheld devices equipped with a touch-sensitive screen. Similar studies have provided recommendations for target sizes when using a mobile device with two hands plus a stylus, and interacting with a desktop-sized display with an index finger, but never for thumbs when holding a small device in a single hand. The first phase explored the required target size for single-target (discrete) pointing tasks, such as activating buttons, radio buttons or checkboxes. The second phase investigated optimal sizes for widgets used for tasks that involve a sequence of taps (serial), such as text entry. Since holding a device in one hand constrains thumb movement, we varied target positions to determine if performance depended on screen location. The results showed that while speed generally improved as targets grew, there were no significant differences in error rate between target sizes ≥ 9.6 mm in discrete tasks and targets ≥ 7.7 mm in serial tasks. Along with subjective ratings and the findings on hit response variability, we found that target size of 9.2 mm for discrete tasks and targets of 9.6 mm for serial tasks should be sufficiently large for one-handed thumb use on touchscreen-based handhelds without degrading performance and preference.

In this paper, we investigate how the choice of media for capture and access affects the diary study method. The diary study is a method of understanding participant behavior and intent in situ that minimizes the effects of observers on participants. We first situate diary studies within a framework of field studies and review related literature. We then report on three diary studies we conducted that involve photographs, audio recordings, location information and tangible artifacts. We then analyze our findings, specifically addressing the following questions: How do context information and episodic memory prompts captured by participants vary with media? In what way do different media “jog ” memory? How do different media affect the diary study process? These questions are particularly important for diary studies because they can be especially useful as compared to other methods when a participant intends to do an action but does not or when actions are particularly difficult to sense. We also built and tested a tool based on participant and researcher frustrations with the method. Our contribution includes suggested modifications to traditional diary techniques that enable annotation and review of captured media; a new variation on the diary study appropriate for researchers using digital capture media; and a lightweight tool to support it, motivated by past work and findings from our studies. Author Keywords Diary studies, qualitative methods

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;

We present the design and evaluation of TapTap and MagStick, two thumb interaction techniques for target acquisition on mobile devices with small touch-screens. These two techniques address all the issues raised by the selection of targets with the thumb on small tactile screens: screen accessibility, visual occlusion and accuracy. A controlled experiment shows that TapTap and MagStick allow the selection of targets in all areas of the screen in a fast and accurate way. They were found to be faster than four previous techniques except Direct Touch which, although faster, is too error prone. They also provided the best error rate of all tested techniques. Finally the paper also provides a comprehensive study of various techniques for thumb based touch-screen target selection. Categories and Subject Descriptors

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ABSTRACT: The rapid growth of mobile telephony has fueled the expansion of the mobile Internet as a foundation for mobile commerce. Proponents claim that mobile commerce will surpass electronic commerce in growth and scope, but there is as yet no commonly accepted framework for the study of interface design for mobile commerce. Using Rayport and Jaworski’s 7C’s—the seven design elements of a customer interface (context, content, community, customization, communication, connection, and commerce) —as a reference framework, interfaces for mobile commerce and electronic commerce are compared. Two new elements (2M’s) are identified: mobile setting and mobile device constraints. These 2M’s substantially affect the design of each of the 7C’s. Therefore, the 2M’s and 7C’s are proposed as a new framework for mobile commerce interfaces. Based on this, previous research is analyzed and suggestions for future research are generated.

Figure 1: (a) Botanists gathering samples in the field. (b) View through a video see-though display of first prototype of the tangible augmented reality user interface. As biodiversity research increases in importance and complexity, the tools that botanists require for field-work must evolve and take on new forms. Of particular importance is the ability to identify existing and new species in the field. Mobile augmented reality systems can make it possible to access, view, and inspect a large database of virtual species examples side-by-side with physical specimens. In this paper, we present prototypes of a mobile augmented reality electronic field guide and techniques for displaying and inspecting computer vision-based visual search results in the form of virtual vouchers. Our work addresses head-movement controlled augmented reality for hands-free interaction and tangible augmented reality. We describe results from our design and investigation process and discuss observations and feedback from lab trials by botanists.

Abstract. In this paper, we present ThumbSpace, a software-based interaction technique that provides general one-handed thumb operation of touchscreenbased mobile devices. Our goals are to provide controlled and accurate selection of all interface objects, especially small and far targets, which are traditionally difficult to interact with using the thumb. ThumbSpace is designed to provide these benefits independent of the application design, which can free designers to focus on effective presentation, as well as efficient interaction when two hands are available. We present the ThumbSpace design and a comparative evaluation against direct interaction for target selection. Our results show that in addition to being well received, ThumbSpace improves accuracy for selecting targets that are out of thumb reach, and makes users as effective at selecting small targets as large targets. The results further suggest user practice and strategic design iterations hold potential to close the gap in access time between the two input methods, where ThumbSpace does not do as well as direct interactions.