Faster Typing on Touchscreen Tablets with New Keyboard Layout
Typing on today's mobile phones and tablets is needlessly slow, claims
researchers...and I concur with them. One limitation is that the QWERTY layout is unsuited for tablets
and other touch-screen devices when typing with the thumbs. Two-thumb typing is
ergonomically very different from typing on a physical keyboard. It has been
established that normal users using a QWERTY on a touch-screen device are
limited to typing at a rate of around...say,... 20 words per minute...give or take.. which is slow
compared to the rates achieved on physical keyboards.
So these researchers set out to create an alternative to QWERTY that offers
substantial performance advantages for users. The researchers incorporated
models of thumb movement into a computational optimization algorithm.
The researchers from the Max Planck Institute for Informatics and colleagues
from the University of St Andrews and Montana Tech quickly realized that slight
changes to the layout, like exchanging a few keys, would not be sufficient for a
significant improvement. Words like "on, see, you, read, dear, immune,
based", frequently used in texts, have to be typed on a split-QWERTY layout
with a single thumb only, making the typing rather burdensome. This initiated the
process to develop a layout for two-thumb text entry with the goal of improving
typing performance and minimizing the strain for the thumbs.
Well, anyone would put tell you that the key to optimizing a keyboard for two thumbs
is to minimize long sequences with a single thumb. We also want to place
frequently used letters centrally close to each other. Note experienced typists move
their thumbs simultaneously: While one is typing, the other is approaching its
next target. Thus these researchers derived a predictive model of this behaviour for the
"optimization method."
The computational optimization process had two goals: To minimize the moving
time of the thumbs and to approximate alternating sides as well as possible. The
result achieved by computational optimization was rather unexpected. In the new
keyboard KALQ, all vowels, with the exception of the letter "y", are
placed in the area for the right thumb, whereas the left thumb gets assigned
more keys. To fully benefit from this layout, the users were trained to move
their thumbs simultaneously. While one thumb is typing, the other one can move
to its next target.
Finally, the authors developed probabilistic error correction methods that
took into account how thumbs move and also statistical knowledge about the texts
users type. Their error correction method enabled trained users to type more
quickly while retaining an acceptable level of errors. With these improvements,
users were able to reach 37 words per minute, which is the best ever reported
for two-thumb typing on touch-screen devices, significantly more than the
approximate 20 words on a split QWERTY that regular users can achieve.
The researchers will present their work at the CHI 2013 conference in Paris
on May 1st.
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