Thumb-Based Approaches to Target Acquisition, Zooming, and Text Entry in Single-Handed Interaction with Mobile Phones
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Date
2016-01-01
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Department
Information Systems
Program
Information Systems
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This item may be protected under Title 17 of the U.S. Copyright Law. It is made available by UMBC for non-commercial research and education. For permission to publish or reproduce, please see http://aok.lib.umbc.edu/specoll/repro.php or contact Special Collections at speccoll(at)umbc.edu
Distribution Rights granted to UMBC by the author.
Distribution Rights granted to UMBC by the author.
Abstract
Single-handed interaction with mobile handheld devices is often desired yet challenging and problematic, especially for users with situational impairments or upper limb disabilities. In this dissertations, three novel thumb-based techniques were designed, developed, and evaluated to address three challenges in single-handed interaction with touch-screen mobile phones, including target acquisition, zooming, and text entry. First, we proposed and developed ExtendedThumb to address the target acquisition problem caused by limited thumb accessibility in single-handed interaction with mobile phones. An empirical user evaluation of ExtendedThumb and two baseline target acquisition techniques, including direct touch and MagStick, was conducted. ExtendedThumb significantly outperforms MagStick in target acquisition speed, perceived ease of use, perceived effectiveness, and overall satisfaction, while achieving a similar level of accuracy. ExtendedThumb also achieves significantly higher performance in user perception than direct touch. Second, ContextZoom was proposed and implemented for single-handed zooming on touch-screen mobile devices. It works as an add-on feature for other existing zooming techniques by supporting zooming in/out a portion of a viewport. The results of an empirical evaluation show that equipped with ContextZoom, users' performances with the Google Maps' single-handed zooming technique and the button-based zooming technique in partial viewport zooming were improved significantly in terms of task completion time and number of discrete actions. Participants also reported higher levels of perceived effectiveness and overall satisfaction with ContextZoom than without ContextZoom while using the Google Maps' single-handed zooming technique, and reported a similar level of perceived ease of use. Third, ThumbStroke was developed to support both single-handed and sight-free text entry. The keyboard allows users to enter text by making strokes with a thumb in any area on a touch screen where they feel comfortable. We evaluated ThumbStroke through a longitudinal lab experiment including 20 sessions with 13 participants, in which participants typed phrases with the ThumbStroke, Escape and QWERTY keyboards. ThumbStroke shows advantages in typing accuracy and user perception in comparison to the other two keyboards and results in faster typing speed than QWRTY in the sight-free condition. The findings of this dissertations provide both research and practical insights for single-handed and sight-free interaction with mobile devices.