The impacts of limited visual feedback on mobile text entry for the Twiddler and mini-QWERTY keyboards

In a mobile environment, the amount of visual attention a person can devote to a computer is often limited. In addition to typing rapidly and accurately, it is important to be able to enter text with limited visual feedback. Previously we found that users can effectively type in such "blind" conditions with the Twiddler one-handed keyboard. In this paper we examine blind typing on mini-QWERTY keyboards and introduce a taxonomy for blind mobile text Input. We present a study in which eight expert mini-QWERTY typists participated in 5 typing sessions. Each session consists of three twenty minute typing conditions. In the first condition, the control or "normal" condition, the participant had full visual access to both the keyboard and the display. In the second condition, "single blind" we obstructed view of the keyboard. The final "double blind" condition also reduced visual feedback from the display. In contrast to our Twiddler work, we found that in the visually impaired conditions, typing rate and accuracy suffer, never reaching the non-blind rates. Across the blind mini-QWERTY conditions our participants averaged 45.8 wpm at 85.6% accuracy, while blind typing on the Twiddler averaged 47.3 wpm at 93.9% accuracy. We discuss these results in the context of our previous blind typing work and examine the trade-offs between the different keyboards for mobile and wearable computer use.