eyes-free text entry with error correction on touchscreen mobile devices
We present an eyes-free text entry method for mobile touchscreen devices. Input progresses by inking Graffiti strokes using a finger on a touchscreen. The system includes a word-level error correction algorithm. Auditory and tactile feedback guide eyes-free entry using speech and non-speech sounds, and by vibrations. In a study with 12 participants, three different feedback modes were tested. Entry speed, accuracy, and algorithm performance were compared between the three feedback modes. An overall entry speed of 10.0 wpm was found with a maximum rate of 21.5 wpm using a feedback mode that required a recognized stroke at the beginning of each word. Text was entered with an overall accuracy of 95.7\%. The error correction algorithm performed well: 14.9\% of entered text was corrected on average, representing a 70.3\% decrease in errors compared to no algorithm. Where multiple candidates appeared, the intended word was 1 st or 2 nd in the list 94.2\% of the time.
eyes-free text entry error correction touchscreen  graffiti  gestural input mobile computing finger input auditory display