Usability of Nomadic User Interfaces

Abstract. During the last decade, a number of research activities have been performed to enable user interfaces and the underlying user activities to be migrated from one device to another. We call this “Nomadic User Interfaces”. The primary goal of these research activities has been to develop the technologies to enable this. However, not much is known about the usability aspects of Nomadic User Interfaces. In this paper we present the results of three different user tests that we conducted to investigate the usefulness and the usability issues of several prototype Nomadic User Interface systems that we developed

Spatial audio in small display screen devices

Our work addresses the problem of (visual) clutter in mobile device interfaces. The solution we propose involves the translation of technique-from the graphical to the audio domain-for expliting space in information representation. This article presents an illustrative example in the form of a spatialisedaudio progress bar. In usability tests, participants performed background monitoring tasks significantly more accurately using this spatialised audio (a compared with a conventional visual) progress bar. Moreover, their performance in a simultaneously running, visually demanding foreground task was significantly improved in the eye-free monitoring condition. These results have important implications for the design of multi-tasking interfaces for mobile devices

CAMMD: Context Aware Mobile Medical Devices

Telemedicine applications on a medical practitioners mobile device should be context-aware. This can vastly improve the effectiveness of mobile applications and is a step towards realising the vision of a ubiquitous telemedicine environment. The nomadic nature of a medical practitioner emphasises location, activity and time as key context-aware elements. An intelligent middleware is needed to effectively interpret and exploit these contextual elements. This paper proposes an agent-based architectural solution called Context-Aware Mobile Medical Devices (CAMMD). This framework can proactively communicate patient records to a portable device based upon the active context of its medical practitioner. An expert system is utilised to cross-reference the context-aware data of location and time against a practitioners work schedule. This proactive distribution of medical data enhances the usability and portability of mobile medical devices. The proposed methodology alleviates constraints on memory storage and enhances user interaction with the handheld device. The framework also improves utilisation of network bandwidth resources. An experimental prototype is presented highlighting the potential of this approach

Nomadic input on mobile devices: the influence of touch input technique and walking speed on performance and offset modeling

In everyday life people use their mobile phones on-the-go with different walking speeds and with different touch input techniques. Unfortunately, much of the published research in mobile interaction does not quantify the influence of these variables. In this paper, we analyze the influence of walking speed, gait pattern and input techniques on commonly used performance parameters like error rate, accuracy and tapping speed, and we compare the results to the static condition. We examine the influence of these factors on the machine learned offset model used to correct user input and we make design recommendations. The results show that all performance parameters degraded when the subject started to move, for all input techniques. Index finger pointing techniques demonstrated overall better performance compared to thumb-pointing techniques. The influence of gait phase on tap event likelihood and accuracy was demonstrated for all input techniques and all walking speeds. Finally, it was shown that the offset model built on static data did not perform as well as models inferred from dynamic data, which indicates the speed-specific nature of the models. Also, models identified using specific input techniques did not perform well when tested in other conditions, demonstrating the limited validity of offset models to a particular input technique. The model was therefore calibrated using data recorded with the appropriate input technique, at 75% of preferred walking speed, which is the speed to which users spontaneously slow down when they use a mobile device and which presents a tradeoff between accuracy and usability. This led to an increase in accuracy compared to models built on static data. The error rate was reduced between 0.05% and 5.3% for landscape-based methods and between 5.3% and 11.9% for portrait-based methods

Kolab: Improvising Nomadic Tangible User Interfaces in the Workplace for Co-Located Collaboration

Tangible User Interfaces (TUIs) [Ishii 1997] offer an interface style that couples "digital information to everyday physical objects and environments" [Ishii 1997 page 2]. However this physicality may also be a limitation as the tendency to use iconic representations for tangibles can result in inflexible 'concrete and specialised objects' [Shaer 2009 page 107]. The current research investigates whether by reducing the dependence on specific tangible sets through the use of improvised tangibles we may begin to address the issue of tangible flexibility within TUIs. Improvised tangibles may be characterised by being potentially arbitrary and abstract, in that they may bear little or no resemblance to the underlying digital value. Core literature in the field (e. g. [Fitzmaurice 1996] [Ishii 2008] [Hornecker 2006] [Holmquist 1999]) suggests that a system based on improvised tangibles would suffer from impaired usability and so the research focuses on the impact on usability due to a lack of close representational significance [Ullmer 2000] during co-located collaboration. Using a prototyping methodology a functional, shareable, TUI system was developed based on computer vision techniques using the Microsoft Kinect [Microsoft2011]. This prototype system ('Kolab') was used to explore an interaction design that supports the dynamic binding of improvised tangibles to digital values. A simple co-located collaborative task was developed using 'Kolab' and a user study was conducted to investigate the usability of the system in a collaborative context. Within the limitations of the simple task the results of the study show that a) users appeared comfortable with improvising artefacts b) the high rate of task completion strongly suggests that a lack of close representational significance does not impair system usability and c) despite some temporary issues with users interfering with other's action an overall indication of equitable participation suggests that collaboration was not impaired by the 'Kolab' prototype

A comparison of feedback cues for enhancing pointing efficiency in interaction with spatial audio displays

An empirical study that compared six different feedback cue types to enhance pointing efficiency in deictic spatial audio displays is presented. Participants were asked to select a sound using a physical pointing gesture, with the help of a loudness cue, a timbre cue and an orientation update cue as well as with combinations of these cues. Display content was varied systematically to investigate the effect of increasing display population. Speed, accuracy and throughput ratings are provided as well as effective target widths that allow for minimal error rates. The results showed direct pointing to be the most efficient interaction technique; however large effective target widths reduce the applicability of this technique. Movement-coupled cues were found to significantly reduce display element size, but resulted in slower interaction and were affected by display content due to the requirement of continuous target attainment. The results show that, with appropriate design, it is possible to overcome interaction uncertainty and provide solutions that are effective in mobile human computer interaction

Kolab: appropriation & improvisation in mobile tangible collaborative interaction

Current design guidelines for conventional tangible systems suggest that the representational significance of tangible tokens is an important consideration in the design of tangible interaction, especially in collaborative contexts. Such advice might be assumed to imply that nomadic tangible systems that employ improvised tokens are liable to have highly impaired usability. In this paper we describe a proof of concept experiment for Kolab, a nomadic tangible interaction system that permits any surface to be appropriated as a collaborative tabletop, and which affords the use of a wide range of appropriated artifacts as improvised tangibles. We demonstrate an approach for realizing the necessary interaction techniques combining tangibles and hand gestures using a fusion of image and depth sensing. We present the results of a user study showing that while users' choices of artifacts were seen to follow an unexpected pattern, various artifacts were appropriated and improvised as tangibles, and the system was found to be both usable and well able to support user collaboration

Effects of feedback, mobility and index of difficulty on deictic spatial audio target acquisition in the horizontal plane

We present the results of an empirical study investigating the effect of feedback, mobility and index of difficulty on a deictic spatial audio target acquisition task in the horizontal plane in front of a user. With audio feedback, spatial audio display elements are found to enable usable deictic interac-tion that can be described using Fitts law. Feedback does not affect perceived workload or preferred walking speed compared to interaction without feedback. Mobility is found to degrade interaction speed and accuracy by 20%. Participants were able to perform deictic spatial audio target acquisition when mobile while walking at 73% of their pre-ferred walking speed. The proposed feedback design is ex-amined in detail and the effects of variable target widths are quantified. Deictic interaction with a spatial audio display is found to be a feasible solution for future interface designs