RESNA 26th International Annual Confence
Although the QWERTY keyboard, the default pattern for virtually all computer and typewriter keyboards in the English speaking world, is adequate for the needs of most able-bodied individuals, it may present significant barriers to the individual with a disability who is limited to single-digit input.
This study compares the QWERTY keyboard (through the reverse-QWERTY protocol presented elsewhere) with the Chubon keyboard, which was designed for single digit typing. The results support the assertion that the Chubon keyboard allows faster text input than the QWERTY, when equal experience is provided.
The first commercially successful typewriter, Sholes & Glidden Type Writer(1) used a keyboard pattern that was designed not to facilitate typing, but to minimize the frequency of mechanical jamming by placing the frequently used letters far apart(2). This keyboard pattern, commonly known as the QWERTY layout, is the default keyboard pattern of typewriters and computers today.
While the QWERTY keyboard is adequate, though sub-optimal for able-bodied typists, it presents a significant barrier for an individual with a disability. Many motor impairments limit the typist to single-digit typing. This may be because of excess muscle tone in the hands, the use of a typing splint, or the use on an on-screen keyboard and mouse emulator for text input. In any of these cases, the wide dispersion of high frequency letters that is a part of the QWERTY design mandates maximum translation of the digit being used for typing. This movement certainly increases the energy expenditure of text generation over a more focused keyboard, and may also decrease the speed of the typist. An inefficient keyboard design can be a barrier to function for the person with a significant distability (3).
In 1988, Chubon and Hester (4) proposed an alternative keyboard pattern for use by single digit typists. The Chubon pattern, as it has become known, organizes the high frequency letters in the center of the keyboard, so that typing becomes more efficient. The overall digit travel using the Chubon keyboard for typing standard English is 34% less than required by the QWERTY keyboard (5). In spite of efforts of the first author to facilitate inclusion of this pattern in the alternative patterns distributed with standard operating systems, it has not be widely accepted due to lack of evidence of its superiority for single digit typists.
The sample for this study consisted of seven able-bodied college students attending a small private college in rural Pennsylvania. The study used able-bodied subjects to separate the effects of disability from the effects of the keyboards.
Using the reverse-QWERTY protocol described elsewhere, each subject typed segments from the novel, "Anne of Green Gables" in 20-minute segments. At the end of each segment, the typing was evaluated for words per minute typed and accuracy. Each subject used one keyboard pattern (Chubon or reverse-QWERTY) until they produced three trials with words per minute rates within 7% of each other, at which time they were considered to have achieved fluency, and were switched to the alternative keyboard pattern. The order of presentation of patterns was balanced to control for learning effects. The levels at fluency were compared only within subject, as no group comparisons are made in a single-subject design.
The number of trials required by each individual to achieve fluency between keyboards was not significantly related, suggesting that the Chubon pattern is neither easier nor harder to learn than the QWERTY pattern. Hence, the first research question can be answered in the negative, there is no learning advantage to either keyboard pattern.
All seven subjects achieved fluency with both the Chubon and reverse-QWERTY keyboard patterns. In each case, the typing speed attained using the Chubon was at least 5% higher than that attained using the reverse-QWERTY, and was as much as 51% higher. Typically, the initial speed of text entry using the Chubon was equal to or greater than the final speed using the reverse-QWERTY. This answers the second research question in the affirmative: the Chubon allowed faster typing for all subjects than the reverse-QWERTY for single digit typing, and by extension (using the reverse-QWERTY protocol) than the standard QWERTY layout.
There were no significant patterns of error related to the keyboard layout or to the number of typed words per minute. The scales of error varied among the individual participants. However, each of the participants remained within an average of 2% of their own error rate with each keyboard layout. This suggests that the degree of error is not specific to the style of the keyboard. The third research question is therefore answered in the negative.
The results of this study support the use of the Chubon keyboard pattern for single-digit typists. While this study explored the use of these two keyboard patterns using the IntelliKeys keyboard, the same results should be found with redefinition of the standard keyboard, with mini-keyboards, or with on-screen keyboards.
Initially, the experienced typist is likely to find the Chubon pattern frustratingly slow, as compared with the long-familiar QWERTY pattern. However, over time, the efficiency of the Chubon pattern should produce faster and easier typing for the individual with a disability. It is the responsibility of the clinician to encourage the individual with an acquired disability to persevere with Chubon pattern until its long-term benefits become evident.