The effects of split versus standard keyboard designs on physiological, performance, and subjective measures of the standing computer user

Abstract

Jobs requiring workers to type for prolonged periods of time are common in industry. Typing intensive jobs can result in pain, numbness, and possibly cumulative trauma disorders. A laboratory study was conducted to evaluate various physiological, performance, and subjective measures and determine the effects of different split and standard keyboard designs on keyboard users. Twelve healthy, college-aged participants (six female and six male) typed in a standing position for two hours per day, four days per week, for the duration of the six-week study. Six different keyboards were profiled (one keyboard per week). The keyboards tested were: IBM standard, IBM standard with wrist rest, IBM split and raised, Microsoft, Kinesis, and Fountain Hill. The following physiological variables were measured: hand and an-n skin temperature, arm volume, vibrotactile sensitivity, nerve conduction velocity, and both systolic and diastolic blood pressures. Also, the performance variables of typing speed and accuracy were measured, as well as the subjective measures of body-part discomfort and keyboard preference. There were no statistically significant differences at the 0.05 level across the six keyboards for any of the physiological measures. However, there were some statistically significant trends indicating physical stress on the user from the task of typing. There was a cooling trend exhibited in both the arm and hand skin temperatures as well as increased vibrotactile sensitivity and increased systolic and diastolic blood pressures during the two hour period. Regarding performance, the participants exhibited significantly (p = 0. 0 1 3 0) slower typing speeds on the split keyboards than on the standard keyboards. There was a tendency toward more accurate typing on the standard keyboards than on the split keyboards; however, this observation was not statistically significant (p = 0.0885). With respect to subjective measures the participants indicated very little pain was experienced on any of the keyboard configurations, but split keyboards were preferred to standard keyboards with respect to design and usability issues. Standard keyboards were perceived easier to learn, but split keyboards were favored for lighter key force and easier keying. The overall keyboard ranking from best to worst showed no statistically significant difference among the keyboards, though.