Chair: Daniel Wigdor, University of Toronto, Canada
Observational and Experimental Investigation of Typing Behaviour using Virtual Keyboards for Mobile Devices
Contribution & Benefit: Observed the typing behaviour of a large number of smartphone users using a mobile game and conducted a large-scale experiment that shows how to improve users' typing performance without costs.
Abstract » With the rise of current smartphones, virtual keyboards for touchscreens became the dominant mobile text entry technique. We developed a typing game that records how users touch on the standard Android keyboard to investigate users' typing behaviour. 47,770,625 keystrokes from 72,945 installations have been collected by publishing the game. By visualizing the touch distribution we identified a systematic skew and derived a function that compensates this skew by shifting touch events. By updating the game we conduct an experiment that investigates the effect of shifting touch events, changing the keys' labels, and visualizing the touched position. Results based on 6,603,659 keystrokes and 13,013 installations show that visualizing the touched positions using a simple dot decreases the error rate of the Android keyboard by 18.3% but also decreases the speed by 5.2% with no positive effect on learnability. The Android keyboard outperforms the control condition but the constructed shift function further improves the performance by 2.2% and decreases the error rate by 9.1%. We argue that the shift function can improve existing keyboards at no costs.ACM
Multidimensional Pareto Optimization of Touchscreen Keyboards for Speed, Familiarity and Improved Spell Checking
Contribution & Benefit: Describes a new approach to keyboard layout optimization for faster text entry with better spell correction on touchscreen phones, while retaining familiarity with Qwerty. Includes designs and user test results.
Abstract » This paper presents a new optimization technique for keyboard layouts based on Pareto front optimization. We used this multifactorial technique to create two new touchscreen phone keyboard layouts based on three design metrics: minimizing finger travel distance in order to maximize text entry speed, a new metric to maximize the quality of spell correction by reducing tap ambiguity, and maximizing familiarity through a similarity function with the standard Qwerty layout. The paper describes the optimization process and resulting layouts for a standard trapezoid shaped keyboard and a more rectangular layout. Fitts' law modelling shows a predicted 11% improvement in entry speed without taking into account the significantly improved error correction potential and the subsequent effect on speed. In initial user tests typing speed dropped from approx. 21 wpm with Qwerty to 13 wpm (64%) on first use of our layout but recovered to 18 wpm (85%) within four short trial sessions, and was still improving. NASA TLX forms showed no significant difference on load between Qwerty and our new layout use in the fourth session. Together we believe this shows the new layouts are faster and can be quickly adopted by users.ACM
Beyond QWERTY: Augmenting Touch Screen Keyboards with Multi-Touch Gestures for Non-Alphanumeric Input
Contribution & Benefit: We introduce a bimanual, multi-touch gestural approach for non-alphanumeric text input on touch-screen keyboards. This technique is designed to augment, not replace, existing solutions.
Abstract » Although many techniques have been proposed to improve text input on touch screens, the vast majority of this research ignores non-alphanumeric input (i.e., punctuation, symbols, and modifiers). To support this input, widely adopted commercial touch-screen interfaces require mode switches to alternate keyboard layouts for most punctuation and symbols. Our approach is to augment existing ten-finger QWERTY keyboards with multi-touch gestural input that can exist as a complement to the moded-keyboard approach. To inform our design, we conducted a study to elicit user-defined gestures from 20 participants. The final gesture set includes both multi-touch and single-touch gestures for commonly used non-alphanumeric text input. We implemented and conducted a preliminary evaluation of a touch-screen keyboard augmented with this technique. Findings show that using gestures for non-alphanumeric input is no slower than using keys, and that users strongly prefer gestures to a moded-keyboard interface.ACM
Touch Typing using Thumbs: Understanding the Effect of Mobility and Hand Posture
Contribution & Benefit: Presents a user study of touch typing whilst walking and the effect of different hand postures and target size. Can assist designers in developing new effective mobile keyboards.
Abstract » Mobile touch devices have become increasingly popular, yet typing on virtual keyboards whilst walking is still an overwhelming task. In this paper we analyze; firstly, the negative effect of walking on text-input performance, particularly the users' main difficulties and error patterns. We focused our research on thumb typing, since this is a commonly used technique to interact with touch interfaces. Secondly, we analyze how these effects can be compensated by two-hand interaction and increasing target size. We asked 22 participants to input text under three mobility conditions (seated, slow walking, and normal walking) and three hand conditions (one-hand/portrait, two-hand/portrait, and two-hand/landscape). Results show that independently of hand condition, mobility significantly decreased input quality, leading to specific error patterns. Moreover, it was shown that target size can compensate the negative effect of walking, while two-hand interaction does not provide additional stability or input accuracy. We finish with implications for future designs.ACM
WalkType: Using Accelerometer Data to Accomodate Situational Impairments in Mobile Touch Screen Text Entry
Contribution & Benefit: Describes an adaptive text entry system that leverages the mobile device's accelerometer to compensate for extraneous movement while walking. This technique can significantly improve typing speed and accuracy.
Abstract » The lack of tactile feedback on touch screens makes typing difficult, a challenge exacerbated when situational impairments like walking vibration and divided attention arise in mobile settings. We introduce WalkType, an adaptive text entry system that leverages the mobile device�s built-in tri-axis accelerometer to compensate for extraneous movement while walking. WalkType�s classification model uses the displacement and acceleration of the device, and inference about the user�s footsteps. Additionally, WalkType models finger-touch location and finger distance traveled on the screen, features that increase overall accuracy regardless of movement. The final model was built on typing data collected from 16 participants. In a study comparing WalkType to a control condition, WalkType reduced uncorrected errors by 45.2% and increased typing speed by 12.9% for walking participants.ACM