Evaluation of Four Wearable Computer Pointing Devices for Drag and Drop Tasks when Stationary and Walking Joanne E. Zucco † , Bruce H. Thomas † , and Karen Grimmer ‡ † Wearable Computer Laboratory School of Computer and Information Science University of South Australia Mawson Lakes, SA, 5095, Australia {jo.zucco, bruce.thomas}@unisa.edu.au ‡ Centre of Allied Health School of Health Sciences University of South Australia Adelaide, SA, 5000, Australia karen.grimmer@unisa.edu.au Abstract This paper presents the results of two experiments comparing four commercially available pointing devices performing drag and drop tasks for use with wearable computers. The pointing devices evaluated consist of a Trackball, Touchpad, Gyroscopic mouse and Twiddler2 mouse. The studies involved 24 participants performing drag and drop tasks with the pointing devices while wearing a wearable computer on their back and using a head-mounted display. The first experiment required participants to perform drag and drop tasks when stationary, while the second experiment required participants to perform drag and drop tasks while walking. The error rate and time to complete the drag and drop of the targets was measured and participants were required to complete an exit questionnaire. The results are presented in this paper. Keywords: Wearable computer, Pointing device, Drag and Drop tasks, Evaluation. 1. Introduction A wearable computer is a physical form of a portable computer. Instead of the computer being handheld, it is attached to the user by a backpack, belt, or in the user’s clothing. The application areas for this form of computer range from navigation and way finding [1], touring of archaeological sites [2], entertainment and gaming [3] and assisting soldiers [4]. Pointing devices are critical to the usability of wearable computers. Traditional workstation pointing devices such as a mouse, joystick and keyboard are not practical for users standing and moving in an indoor/outdoor environment, as these devices require a level, flat surface to operate. A new form of pointing device is therefore required. Pointing devices better suited for use with wearable computers are emerging from research laboratories and as commercial products. To date, there have been a limited number of empirical studies investigating the usability of pointing devices for wearable computers. We previously presented a usability study which compares three commercially available pointing devices performing cursor movement and selection tasks for use with wearable computers [13] while stationary. Although interaction models for wearable computers may differ from those used in desktop computers, we believe that it is important to explore all possible pointing interaction models in a wearable context. The two studies presented in this paper extend our selection study by evaluating the pointing devices when performing an increasingly complex task. The usability studies presented in this paper compare four commercially available pointing devices (a trackball, touchpad, gyroscopic mouse and Twiddler2 mouse), performing drag and drop tasks for use with wearable computers. In the first usability study, participants carried out multiple operations of a drag and drop task while stationary. For the second usability study, participants performed the same drag and drop tasks while walking. We are interested in determining whether certain devices are better suited to certain tasks or whether there is an optimal pointing device in terms of operator performance over a suite of tasks. In doing so, we aim to be able to produce findings that will guide users and designers in selecting an input device that is appropriate for their task(s). 1.1. Motivation The aim of both the stationary and walking experiments was to determine whether there was any measurable difference to a user operating a wearable computer using the different pointing devices. The studies objectives were as follows: 1. To determine whether there was a measurable difference in speed when performing drag and drop tasks with the four different pointing devices. 2. To determine whether there was a measurable difference in accuracy when performing drag and drop tasks with the four different pointing devices. 1-4244-0598-X /06/$20.00 ©2006 IEEE.