Learning Curve Analysis for Alternative Keyboards

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Title: Learning Curve Analysis for Alternative Keyboards
Author: Anderson, Allison M
Advisors: Gary Mirka, PhD, Committee Chair
Sharon Joines, Committee Member
David Kaber, PhD, Committee Member
Abstract: Although research has shown that alternative keyboards can offer ergonomic benefits over the standard QWERTY keyboard, the simple single-plane QWERTY layout is still the most widely used keyboard design. One of the hypothesized reasons for this resistance to change is the expected time to learn a new layout of the keys or time to become accustomed to a modified keyboard profile/orientation (e.g. split, contoured). To begin to address this concern, the current study was performed to quantify learning rates for four alternative keyboards (a chord keypad, a contoured split keyboard, a Dvorak layout keyboard, and a fixed split keyboard). To gain a deeper understanding of the underlying phenomenon that may lead to differences in learning rate, this study also sought to understand how physical, cognitive, and perceptual demands of the different keyboard design affect this learning rate. Sixteen proficient typists participated in five, three-sentence typing trials on each alternative keyboard. Time-to-complete and error percentage were collected after every trial, and subsequent learning rates were calculated. Upon completion of each trial, subjects completed a subjective questionnaire that asked them to evaluate the physical, the perceptual, and the cognitive demands posed by each keyboard. Finally, in an effort to assess the quality of the predictions of the learning rate of these five trial sessions, nine different subjects performed the typing trials 20 times on one of the alternate keyboard designs so that a comparison could be made between the learning rate estimate of 5 typing trials and 20 typing trials. Results demonstrated five trials were sufficient to provide stable estimates of the learning rates for each keyboard. The results also showed that the learning rate for the fixed split keyboard (90.4%) was significantly different (F=23.25, p<0.001) from the learning rates for the other three keyboards (chord: 77.3%, contour split: 76.9%, Dvorak: 79.1%). Previous studies have suggested that cognitive tasks have a learning rate of 70% while physical tasks would have a learning rate of 90%. Our results indicate that the fixed split keyboard was primarily a physical intervention while the other keyboards appear to have both a physical and cognitive learning component. Learning rate was negatively correlated to all types of demand (physical, cognitive, and perceptual), meaning that learning rate was slower with higher demand, regardless of the type of demand. Productivity is also an important measure when implementing an ergonomic intervention. The average time for the QWERTY trials (control condition) was 40.2 seconds, and the average time for the 5th trial on the split keyboard was 42.4 seconds (only 5% slower than QWERTY). Also, after 20 trials on the contour split keyboard, subjects were able to type each trial in an average of 44 seconds, within 10% of typing speed on the QWERTY keyboard. These two alternative keyboards utilize the QWERTY key layout but are physically shaped differently to promote more neutral wrist postures. Subjects were able to regain typing speeds on these two keyboards, but trial times were much slower on the other two keyboards given the higher cognitive demands. This study successfully applied learning curve theory to the implementation of alternative keyboards. The results show that productivity decrements can be quickly regained for the fixed split and contour split keyboard. Many alternative keyboards have been shown to have ergonomic benefits and the results of this study would indicate that the learning rates associated with some of the keyboard designs are such that they can easily be implemented into the workplace without long-term productivity decrements.
Date: 2007-07-25
Degree: MS
Discipline: Industrial Engineering
URI: http://www.lib.ncsu.edu/resolver/1840.16/2108


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