Research Study - Ergonomic Test of the Kinesis Contoured Keyboard - 5

ISO Performance Calculations:
The ISO test protocol requires that performance analysis be conducted on the middle three test sessions (i.e., 3, 4, and 5). Due to a required modification of the protocol, calculations were performed on the last session as well; this test thus included analysis of sessions 3, 4, 5, and 6. This allowed calculations on the last two text entry sessions and the two random letter entry sessions and thus equal sample calculations for each task (i.e., text and random entry).

The ISO protocol also requires that calculations be conducted on four measures: 1) keying rate, 2) average error rate, 3) distribution of scores on the acceptability scale, and 4) comparative judgment of acceptability.

ISO specifies that a difference in performance which constitutes unacceptable performance is a difference greater than 0.75 SD (standard deviation) from the reference i.e., traditional) keyboard in the direction of poorer performance.

Calculations of keying performance (see Appendix B) demonstrated that all of the ISO required measures of subject performance (KPS or keystrokes per second, errors and error rate), except throughput (by 1.5 WPM or words per minute), showed no significant differences and thus were inside the ISO standard keyboard acceptable range (see Figure 10).

ISO Acceptability Limits

ISO Compliance Limits and Kinesis Performance Scores

Preferences
Subjects were administered three different types of questionnaires (see Appendices C, D, E and F).

Questionnaire 1 was developed by Kinesis and asked questions regarding impressions of each keyboard immediately after its use. The results of Questionnaire 1 showed subjects' impressions to be nearly the same for each keyboard. Slightly more subjects preferred the Kinesis for comfort, and slightly more subjects preferred the traditional keyboard for confidence and performance.

Questionnaire 2 was also developed by Kinesis and asked subjects to indicate their keyboard preferences after they had used both keyboards. Results of Questionnaire 2 showed that subjects preferred the Kinesis in most of the categories listed except speed, accuracy, confidence and function keys (although the function keys were never used during any of the testing procedures). Subjects indicated considerable preference for the Kinesis in areas of comfort, fatigue, usability and preferred the Kinesis by almost two to one as an overall choice.

Questionnaire 3 was from the ISO test protocol Subjects completed the questionnaire following testing on the first keyboard and again after testing on the second keyboard They rated various aspects of the first keyboard such as comfort and usability on a continuous scale and rated the second keyboard by indicating only if they thought it was worse, better or the same as the first keyboard. This procedure allowed the subjects to observe their impressions immediately following usage of the first keyboard and judge the second accordingly. Results of the ISO comparison showed almost no difference in preference in most categories except for aches/pains, tiredness and posture, where subjects showed a preference for the Kinesis keyboard.

Discussion
Keying Performance Although subjects only had 7 hours of training on the Kinesis keyboard, keying performance was almost up to their performance level on a traditional keyboard. Past studies of keyboards radically different than the traditional keyboard have demonstrated that subjects require about one week of keying to reach their traditional keying rate. This may also be the case for the Kinesis keyboard as visual inspection of the plotted data indicates continuing throughput improvement.

The placement of the hands, keying motion, and the shape of the Kinesis keyboard are significantly different than the traditional keyboard and could account for the lower performance. Also, because of the Kinesis unique design, users may have been more cautious while keying and thus slower.

Hand Angle
Research indicates that hand extension beyond 15 degrees for an extended period of time is highly correlated with hand repetitive strain disorders and injuries. Subjects keying on the traditional keyboard typically had substantially greater hand extension and ulnar deviation than when keying on the Kinesis keyboard. These results were demonstrated in both the EMG and postural analysis.

Preferences
Subjects showed an overall preference for the Kinesis keyboard on most characteristics. The positive impressions after using the Kinesis keyboard appeared to overcome the initial trepidation subjects may have had from the initial exposure to its unique design

Conclusions
The Kinesis keyboard demonstrated substantial physiological advantages, good performance, and more preferences compared to the traditional keyboard. Of the measures taken in this study, the only one (i.e., throughput) in which Kinesis was not as good as the traditional was the one where subjects might most easily improve with practice.

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