Effects of Computer Keyboard Setup Parameters and User's Anthropometric Characteristics on Wrist Deviation and Typing Efficiency

Abstract

Two questions that computer keyboard operators face when using keyboards that can be separated into halves (split keyboards) are at what angle should the keyboard halves be opened and at what distance should the keyboard halves be placed apart. The objective of this study was to investigate the effects of the opening angle and separation distance between halves of a split keyboard on wrist radial/ulnar deviation and typing efficiency. Eleven experienced typists participated in this study and typed on a split keyboard configured in the following four arrangements.

The keyboard halves were setup the same way as a conventional keyboard.

The keyboard halves were contiguous but angled, based on the user's anthropometry, to maintain a theoretical neutral posture of the user's wrists in the radial/ulnar plane.

The keyboard halves were separated at a fixed distance of 20 cm, and the halves were angled to maintain a theoretical neutral posture of the user's wrists in the radial/ulnar plane.

The keyboard halves were separated at a distance equal to the user's shoulder width, and the halves were parallel to each other, resulting in a theoretical neutral posture of the user's wrists in the radial/ulnar plane.

The findings from testing these four keyboard configurations are the following:

The mean ulnar deviations from the alternative configurations of the split keyboard (configurations 2, 3, and 4 above) ranged from 7.0 to 8.4 for the left wrist and 2.7 to 5 deg. for the right wrist. There were no significant differences in ulnar deviations among the three alternative configurations.

The three alternative configurations resulted in ulnar deviation of both wrists that were significantly less than ulnar deviation from typing on the conventional setup (configuration 1 above). The mean ulnar deviations from the conventional setup were 18.9 deg. for the left wrist and 14.2 deg. for the right wrist.

There were no significant differences in typing speed and accuracy between the alternative and conventional configurations.

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