Research Study - Ergonomic Test of the Kinesis Contoured Keyboard

Prepared by
Wanda Smith, President
Dan Cronin, Engineer
December 16, 1992

Executive Summary
A study was conducted of postures, muscle activity, keying performance and preferences of subjects keying on a standard (traditional type) keyboard and the Kinesis keyboard.The main purpose of the study was to determine if the design of the Kinesis keyboard resulted in reduced muscle load, improved performance, and was preferred to a traditional keyboard.

Twenty five subjects participated in the test. Each subject was required to key text and random letters for six 20-minute sessions on each of the two (traditional and Kinesis) keyboards. Subjects were given seven hours of keying practice on the Kinesis keyboard the day before the test.

Throughout the test, measures were taken of hand angles, electrical muscle potential, keying (speed and accuracy), and comparative ratings of each keyboard.

Postural analysis showed hand deviation and extension were substantially less on the Kinesis keyboard than on the traditional keyboard.

Analysis of muscle load revealed substantially less load on muscles controlling hand deviation, extension, and pronation on the Kinesis keyboard. Subjects exhibited virtually the same muscle load for elbow adbuction for both keyboards by the end of each test.

Analysis of subjects' performance showed a statistically significant increase in throughput for test entry when subjects used the traditional keyboard, but no significant difference in error frequency between the two keyboards.

Subjects indicated substantial preference for the Kinesis in areas of comfort, fatigue, and usability. They preferred the Kinesis by almost two to one as an overall choice.

Introduction

The design of the Kinesis keyboard is radically different than a traditional keyboard. On the Kinesis keyboard, the traditional QWERTY keyboard layout is located in two separate sections, one on each side of the keyboard. The Kinesis key field profile is concave; special keys (like Backspace, Delete and Enter) are located in the center of the key area at approximately a 60 degree angle to the front edge of the keyboard or there is a built-in palm rest.

A primary purpose of the design of the Kinesis keyboard is to reduce stress on the upper body and the hands from the keying force, ulnar-lateral deviation, and extension that often occur while using a traditionally designed keyboard. The Kinesis intends to achieve these results by customizing and reducing displacement force of specific keys, customizing the shape of the keys to the shape of the fingers, separating keying sections, and providing a palm rest.

The following test was conducted to determine the extent that the Kinesis keyboard reduces muscle load, and compares to the traditional keyboard in performance and preference.

Method
The experimental protocol used in this study was based on that as specified in the Part 4 (Keyboard Requirements) draft of the ISO ergonomic standard 9241. Part 4 specifies test subjects, stimuli, experimental design, environmental conditions, furniture adjustments, performance data analysis, and a preference metric.

Subjects
Twenty-five subjects (20 women and 5 men) between 20 to 60 years of age participated in the study; eleven of these subjects participated in the EMG analysis (see Figure l). The subjects were obtained from a temporary employment agency and all pre-tested at a typing proficiency of at least 45 words per minute. All subjects had several years' experience using traditional computer keyboards.

Figure 1:

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