Nikola Banovic, Koji Yatani, and Khai Truong
Mobile text entry methods traditionally have been designed with the assumption that users can devote full visual and mental attention on the device though this is not always possible. In this paper, we present the design and evaluation of Escape-Keyboard, a sight-free text entry method for mobile touch-screen devices. Escape-Keyboard allows the user to type letters with one hand by pressing the thumb on different areas of the screen and consequently performing a flick gesture. Our user study showed that participants reached an average typing speed of 14.7 words per minute (WPM) with 4.4% error rate in the sight-free condition and 16.8 WPM with 1.7% error rate in the sighted condition after 16 typing sessions. Our qualitative results indicate that the participants had difficulty learning the keyboard layout, which led to slow typing speed improvements over time. We thus implemented and evaluated features to mitigate this learnability issue. We also performed a theoretical analysis of sight-free performance of our keyboard, which predicts expert peak performance to be 39 WPM.
|Published in||International Journal of Mobile Human Computer Interaction (IJMHCI)|