A Single-Handed Partial Zooming Technique for Touch-Screen Mobile Devices

Despite its ubiquitous use, the pinch zooming technique is not effective for one-handed interaction. We propose ContextZoom, a novel technique for single-handed zooming on touch-screen mobile devices. It allows users to specify any place on a device screen as the zooming center to ensure that the intended zooming target is always visible on the screen after zooming. ContextZoom supports zooming in/out a portion of a viewport, and provides a quick switch between the partial and whole viewports. We conducted an empirical evaluation of ContextZoom through a controlled lab experiment to compare ContextZoom and the Google maps’ single-handed zooming technique. Results show that ContextZoom outperforms the latter in task completion time and the number of discrete actions taken. Participants also reported higher levels of perceived effectiveness and overall satisfaction with ContextZoom than with the Google maps’ single-handed zooming technique, as well as a similar level of perceived ease of use

Curseur Tangible et Déformable sur Dispositifs Mobiles pour Interagir à une Main sans Regarder l'Écran

International audienceGraphical sliders are widely used on mobile devices. However, with a single hand, reaching for far values is difficult : users change their grip and can drop the device. Moreover, sliders require visual attention to operate them. Envisioning mobile devices that dynamically extend tangible sliders out of the screen, the contribution of this work is a first attempt to experimentally study a deformable tangible slider that facilitate thumb interaction on mobile devices. The deformable tangible slider expands its cursor (Figure 1) to avoid hand-grip changes by maintaining the thumb within its comfortable area. Moreover, its tangible aspect allows eyes-free interaction. We first compared a low-fidelity prototype with a classic tangible slider. The prototype improves performance by 9.2% when targets are outside the thumb's comfortable area. We then designed a de-formable slider that we compared to a classic tangible slider and a graphical one. Though the deformable slider is globally faster (14.3%) than the classic tangible one, the difference is not significant. While the graphical slider performs faster, the deformable tangible slider o ers eyes- free interaction and stable hand-grip.Les curseurs graphiques sont largement utilisés sur les dispositifs mobiles. Cependant, atteindre des valeurs éloignées avec le pouce de la main qui tient le dispositif est difficile : les utilisateurs changent alors la prise en main du dispositif au risque de le faire tomber. De plus, les curseurs graphiques sollicitent l’attention visuelle pour les manipuler. En anticipant que les dispositifs mobiles pourront faire émerger de leurs écrans des curseurs physiques dynamiquement, notre contribution est une première exploration expérimentale d’un curseur tangible qui se déforme pour faciliter l’interaction mobile avec le pouce de la main qui tient le dispositif. Le curseur tangible se déforme pour que le pouce manipule toujours le curseur dans la zone d’action facilement atteignable (Fig. 1). Le curseur tangible déformable (1) évite les changements de prise en main en maintenant le pouce dans sa zone de confort, et (2) permet une interaction sans regarder le dispositif mobile. Nous avons d’abord comparé un prototype basse-fidélité avec un curseur classique tangible. Le prototype améliore les performances de 9.2% lorsque les cibles sont en dehors de la zone de confort du pouce. Nous avons ensuite conçu un curseur déformable que nous avons comparé à un curseur tangible classique et à un curseur graphique. Les résultats expérimentaux démontrent que le curseur tangible déformable est globalement plus rapide de 14.3% que le curseur tangible classique sans que les résultats soient significativement différents. Alors que le curseur graphique o re de meilleures performances que les deux autres curseurs tangibles, le curseur tangible déformable o re une interac- tion sans regarder le dispositif avec une prise en main du dispositif stable

Supporting Transitions To Expertise In Hidden Toolbars

Hidden toolbars are becoming common on mobile devices. These techniques maximize the space available for application content by keeping tools off-screen until needed. However, current designs require several actions to make a selection, and they do not provide shortcuts for users who have become familiar with the toolbar. To better understand the performance capabilities and tradeoffs involved in hidden toolbars, we outline a design space that captures the key elements of these controls and report on an empirical evaluation of four designs. Two of our designs provide shortcuts that are based on the user’s spatial memory of item locations. The study found that toolbars with spatial-memory shortcuts had significantly better performance (700ms faster) than standard designs currently in use. Participants quickly learned the shortcut selection method (although switching to a memory-based method led to higher error rates than the visually-guided techniques). Participants strongly preferred one of the shortcut methods that allowed selections by swiping across the screen bezel at the location of the desired item. This work shows that shortcut techniques are feasible and desirable on touch devices and shows that spatial memory can provide a foundation for designing shortcuts

The effects of encumbrance and mobility on interactions with touchscreen mobile devices

Mobile handheld devices such as smartphones are now convenient as they allow users to make calls, reply to emails, find nearby services and many more. The increase in functionality and availability of mobile applications also allow mobile devices to be used in many different everyday situations (for example, while on the move and carrying items). While previous work has investigated the interaction difficulties in walking situations, there is a lack of empirical work in the literature on mobile input when users are physically constrained by other activities. As a result, how users input on touchscreen handheld devices in encumbered and mobile contexts is less well known and deserves more attention to examine the usability issues that are often ignored. This thesis investigates targeting performance on touchscreen mobile phones in one common encumbered situation - when users are carrying everyday objects while on the move. To identify the typical objects held during mobile interactions and define a set of common encumbrance scenarios to evaluate in subsequent user studies, Chapter 3 describes an observational study that examined users in different public locations. The results showed that people carried different types of bags and boxes the most frequently. To measure how much tapping performance on touchscreen mobile phones is affected, Chapter 4 examines a range of encumbrance scenarios, which includes holding a bag in-hand or a box underarm, either on the dominant or non-dominant side, during target selections on a mobile phone. Users are likely to switch to a more effective input posture when encumbered and on the move, so Chapter 5 investigates one- and two- handed encumbered interactions and evaluates situations where both hands are occupied with multiple objects. Touchscreen devices afford various multi-touch input types, so Chapter 6 compares the performance of four main one- and two- finger gesture inputs: tapping, dragging, spreading & pinching and rotating, while walking and encumbered. Several main evaluation approaches have been used in previous walking studies, but more attention is required when the effects of encumbrance is also being examined. Chapter 7 examines the appropriateness of two methods (ground and treadmill walking) for encumbered and walking studies, justifies the need to control walking speed and examines the effects of varying walking speed (i.e. walking slower or faster than normal) on encumbered targeting performance. The studies all showed a reduction in targeting performance when users were walking and encumbered, so Chapter 8 explores two ways to improve target selections. The first approach defines a target size, based on the results collected from earlier studies, to increase tapping accuracy and subsequently, a novel interface arrangement was designed which optimises screen space more effectively. The second approach evaluates a benchmark pointing technique, which has shown to improve the selection of small targets, to see if it is useful in walking and encumbered contexts