ARTICLE IN PRESS International Journal of Industrial Ergonomics xxx (2008) 1–8 Contents lists available at ScienceDirect International Journal of Industrial Ergonomics journal homepage: www.elsevier.com/locate/ergon Design and evaluation of dynamic text-editing methods using foot pedals Sang-Hwan Kim, David B. Kaber* Edward P. Fitts Department of Industrial and Systems Engineering, North Carolina State University, 111 Lampe Dr., 438 Daniels Hall, Raleigh, NC 27695-7906, USA article info abstract Article history: The objective of this study was to design and evaluate new dynamic text-editing methods (chatting, instant Received 11 February 2008 messenger) using a foot pedal control. A first experiment was to assess whether the foot-based method Received in revised form 30 June 2008 enhanced editing performance compared to conventional mouse use and to identify which type of foot Accepted 15 July 2008 control is most convenient for users. Five prototype methods including four new methods (two pedals or Available online xxx one pedal, 0 order or 1st order control), and one mouse method were developed and tested by performing a task requiring changing text sizes, dynamically. Results revealed methods involving 1st order pedal control Keywords: to be comparable to the conventional method in task completion time, accuracy and subjective workload. Foot pedals Text editing Among the four foot control prototypes, two pedals with 1st order control was superior to in performance. A Control systems second experiment was conducted to test another prototype foot-based method for controlling font face, size, and color through feature selection with the left pedal and level selection with the right pedal. Text- editing performance was compared to conventional mouse-based editing. Results showed the foot pedals to degrade performance in terms of task completion time. However, the prototype interface has the advantage of making certain system functionality accessible to special populations that might not otherwise be able to use dynamic text-editing applications. Subjective comments demonstrated the foot pedal methods to be considered useful, time efficient and to reduce workload. It was observed that skilled users might perceive some relief from cumbersome mouse handling behaviors during typing. Although the foot pedal control was not revealed to significantly increase text-editing performance over conventional mousing, the use of foot pedals may be considered in computing operations, including dynamic text-editing tasks, as an alternative or additional input method, particularly for special populations. Relevance to industry: The development and evaluation of foot control interaction methods for text editing may provide useful insight for human-computer system designers considering the use of additional input devices or ways to support user expressions of emotion in text. The foot control approach may also be useful in interaction design for special populations (with functional limitations of the upper limbs) in terms of accessibility. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction research has shown the feet are slower and less accurate than the hands (Kroemer, 1971), and foot controls often restrict user posture. 1.1. Foot controls Having to maintain a foot on a control makes it more difficult to shift posture in a seat or change the position of the legs, for example. As the computer has become a common tool in the work envi- Operating foot controls from a standing position also requires people ronment,functionsusedbyhumanshavebecomemoreandmore to balance their weight on one foot at a time. Despite these issues, foot complicated and require various types of interaction. This has led to controls have continued to have a place in control tasks (see Sanders development and use of hand-control input devices such as and McCormick (1993: Chapter 11) for other examples). Several keyboards, mice, trackballs and joysticks. Human foot control devices research studies have been conducted to identify design parameters are also essential to modern life including working with vehicles. In affecting performance with foot controls. Ayoub and Trombley (1967) order to use a foot to control a system, pedals have been designed and investigated travel time in pedal movement with various fulcrum developed for specific tasks (e.g., pedals for aircraft rudder control). locations, and Drury (1975) developed a modified version of Fitt’s law However, hand controls are, far and away, more widely employed for to predict movement time in moving a foot from one pedal to another machine control. One reason for this is that prior human factors’ pedal. This work has been used as a basis for effective pedal design in, for example, automobiles (Morrison et al., 1986). * Corresponding author. Tel.: þ1 919 515 3086; fax: þ1 919 515 5281. The most commonly used foot controls are the brake and accel- E-mail address: [email protected] (D.B. Kaber). erator pedal controls of automobiles. People who do not have 0169-8141/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.ergon.2008.07.010 Please cite this article in press as: Kim, S.-H., David B. Kaber, Design and evaluation of dynamic text-editing methods using foot pedals, International Journal of Industrial Ergonomics (2008), doi:10.1016/j.ergon.2008.07.010 ARTICLE IN PRESS 2 S.-H. Kim, D.B. Kaber / International Journal of Industrial Ergonomics xxx (2008) 1–8 functional limitations in foot and cognitive activities make contin- use menu in the Kinedit tool. With this in mind, we hypothesized uous use of foot control pedals in driving a car without distinctive that use of foot controls to allow the hand to remain on a keyboard difficulties. Foot pedals are also used frequently with musical while the feet are used to adjust text properties in a dynamic tex- instruments including pianos, electric guitars, organs and drums, and t-editing application such as chatting and instant messenger would in other mechanical equipment including, cranes, sewing machines also serve to promote application effectiveness. and industrial controls. On this basis, it may be advantageous to incorporate foot controls in human–computer interaction tasks (Dix 1.3. Research objective et al., 2004). Some researchers have investigated the use of foot pedals with desktop computing applications. Mohamed and Fels At this time, there are no common foot pedal devices and (2002a,b) invented and introduced a system for controlling music applications for desktop computing. The functionality of prototype sequencing software from a piano keyboard and by adding a foot devices has been limited to the foot pedal being used for simple, switch. The system eliminated the need for a computer keyboard and discrete or binary selection of modes of system operation and not mouse by relocating their functions to the piano keyboard, and the for continuous control. The objective of this study was to investi- foot switch was used as a mode control to distinguish between gate whether a new methodology for text editing, using a foot keystrokes representing notes and macros. An experiment was control pedal with continuous control, is accessible and acceptable conducted to compare the two methods of conventional computer to users for dynamic text-editing performance involving frequent/ keyboard use and the new piano controls. They found the foot pedal dynamic typeface changes. A first experiment was conducted to to be effective for preventing mode errors. Sellen et al. (1992) identify which type of foot control (using two pedals vs. one pedal, examined the effectiveness of a foot pedal to present kinesthetic using a 0 order or 1st order control system) most convenient for feedback to users and prevent mode errors in a text-editing task setting text size in document editing. In addition to this, the through two experiments. Results showed the foot pedal feedback to method for setting a specific property of text using the foot pedal be successful and to reduce cognitive load. Both of the studies was compared to mouse-based editing methods for the same task. mentioned above considered foot pedals as devices to select discrete In a second experiment, we tested another prototype, which was modes of control. Of course foot pedals can also be used for designed to control the font face, size, and color through mode controlling continuous properties, like a gas pedal in an automobile. selection with the left foot pedal while using the right foot pedal for setting each property. Performance using this prototype was also 1.2. Typography and kinetic text compared to a mouse-based method of editing. Text editing is one of the most dominant tasks in computing 2. Experiment 1 operations. In office environment, many workers see and edit text material displayed on a screen through computers. In spite of the Because current editing methods involving a mouse may require extensive use of interfaces for text editing, the vast majority of frequent hand repositioning to select a specific text property, in this applications are less effective than they could be. In order to experiment we hypothesized that the new foot control prototype enhance the visualization effectiveness of text information, some would produce significant reductions in text-editing time, errors studies have examined typography in displays. Typography was and perceived workload. We also expected that the action of a single first considered for providing implicit information beyond external pedal would require