A team at the Max Planck Institute for Informatics reported computational optimization techniques in conjunction with a model of thumb movement were applied to millions of potential keyboard layouts to identify one that yields superior performance.
The traditional QWERTY layout is ill-suited for tablets and other touchscreen devices when typing with the thumbs, the researchers said, and two-thumb typing is ergonomically very different from typing on a physical keyboard.
"The key to optimizing a keyboard for two thumbs is to minimize long sequences with a single thumb," researcher Antti Oulasvirta said. "We also want to place frequently used letters centrally close to each other.
"Experienced typists move their thumbs simultaneously: While one is typing, the other is approaching its next target. We derived a predictive model of this behavior for the optimization method."
The result, dubbed the KALQ keyboard, allowed users after a short period of practice to type 34 percent faster than they could with a QWERTY layout, the researchers said.
In the KALQ keyboard 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 take advantage of this layout, users were trained to move their thumbs simultaneously, typing with one while the other moved on to its next target.
"The legacy of QWERTY has trapped users with suboptimal text entry interfaces on mobile devices," researcher Per Ola Kristensson said. "However, before abandoning QWERTY, users rightfully demand a compelling alternative. We believe KALQ provides a large enough performance improvement to give users the incentive to switch and benefit from faster and more comfortable typing."