Motor-impaired Users Research Articles

A robust design for accessible text entry

This paper describes the author's dissertation research on designing, implementing, and evaluating the Edge Write text entry method. The goal of this research is to develop a method that is highly "robust," remaining accessible and accurate across a variety of devices, abilities, circumstances, and constraints. Edge Write is particularly aimed at users with motor impairments and able-bodied users "on the go." To date, this research has resulted in versions of Edge Write for PDAs, touchpads, displacement joysticks, isometric joysticks, trackballs, 4-keys, and more, all of which use the same Edge Write alphabet and concepts. The stylus version, for instance, has been shown to be significantly more accurate than Graffiti for both able-bodied and motor-impaired users. Similarly, the trackball version has been shown to be better than on-screen keyboards for some people who use trackballs due to motor impairments. This paper discusses these and other achievements, and points towards future work on a mobile phone version for situationally-impaired users. From its inception, Edge Write has been developed with the help of participants, both able-bodied and motor-impaired.

Movement time for motion-impaired users assisted by force-feedback: effects of movement amplitude, target width, and gravity well width

This paper presents a study investigating how the performance of motion-impaired computer users in “point and click” tasks varies with target distance (A), target width (W), and force-feedback gravity well width (GWW). Six motion-impaired users performed “point and click” tasks across a range of values for A, W, and GWW. Times were observed to increase with A, and to decrease with W. Times also improved with GWW, and, with the addition of a gravity well, a greater improvement was observed for smaller targets than for bigger ones. It was found that Fitts’ Law gave a good description of behaviour for each value of GWW, and that gravity wells reduced the effect of task difficulty on performance. A model based on Fitts’ Law is proposed, which incorporates the effect of GWW on movement time. The model accounts for 88.8% of the variance in the observed data.

A submovement analysis of cursor trajectories

Understanding human movement is key to improving input devices and interaction techniques. This paper presents a study of mouse movements of motion-impaired users, with an aim to gaining a better understanding of impaired movement. The cursor trajectories of six motion-impaired users and three able-bodied users are studied according to their submovement structure. Performance measures based on submovement structure are described, including the frequency and duration of pauses between submovements, verification times, the number of submovements, the peak speed of submovements and the accuracy of submovements in two dimensions. The measures are shown to be sensitive to differences between users with dissimilar physical capabilities. Results include findings that some motion-impaired users pause more often and for longer than able-bodied users, require up to five times more submovements to complete the same task, and exhibit a greater decline in accuracy with increasing speed than able-bodied users.

Taking handheld devices to the next level

Wireless technologies such as Bluetooth and IEEE 802.11 (Wi-Fi), handheld devices are communicating more frequently with conventional computers in offices, meeting rooms, classrooms, and homes. The smart homes of the future will have ubiquitous embedded computation, and an increasing number of appliances can already communicate wirelessly. The authors launched the Pebbles project to determine whether a handheld device, such as a personal digital assistant (PDA) or cell phone, could serve as a simpler, more effective remote control. Office-centered applications include using the PDA instead of a laser pointer, using a PDA to remotely control a PowerPoint presentation, and using a PDA with the nondominant hand to scroll windows on a PC. In the home, we are exploring how to use the PDA as a customizable, intelligent personal universal controller (PUC) for appliances, creating high-quality control panels on the handheld using a high-level specification of the appliance's capabilities. We are also interested in how PDAs can assist in providing both appliance and computer access for the disabled, including the development of new text entry methods for the motor-impaired user.

Mouse movements of motion-impaired users: a submovement analysis

Understanding human movement is key to improving input devices and interaction techniques. This paper presents a study of mouse movements of motion-impaired users, with an aim to gaining a better understanding of impaired movement. The cursor trajectories of six motion-impaired users and three able-bodied users are studied according to their submovement structure. Several aspects of the movement are studied, including the frequency and duration of pauses between submovements, verification times, the number of submovements, the peak speed of submovements and the accuracy of submovements in two-dimensions. Results include findings that some motion-impaired users pause more often and for longer than able-bodied users, require up to five times more submovements to complete the same task, and exhibit a correlation between error and peak submovement speed that does not exist for able-bodied users.

Social and collaborative aspects of interaction with a service robot

To an increasing extent, robots are being designed to become a part of the lives of ordinary people. This calls for new models of the interaction between humans and robots, taking advantage of human social and communicative skills. Furthermore, human–robot relationships must be understood in the context of use of robots, and based on empirical studies of humans and robots in real settings. This paper discusses social aspects of interaction with a service robot, departing from our experiences of designing a fetch-and-carry robot for motion-impaired users in an office environment. We present the motivations behind the design of the Cero robot, especially its communication paradigm. Finally, we discuss experiences from a recent usage study, and research issues emerging from this work. A conclusion is that addressing only the primary user in service robotics is unsatisfactory, and that the focus should be on the setting, activities and social interactions of the group of people where the robot is to be used.

Automatic visual recognition of gestures made by motor-impaired computer users

The use of gesture recognition as a means of Human Computer Interaction for physically disabled users is discussed. The ability of motor-impaired computer users to make distinct, recognisable gestures is not exploited by current assistive technologies. A real-time computer vision system for recognition of one- and two-handed gestures defined by such users is described. An investigation into the feasibility of real-time, unencumbered recognition of gestures defined by motor-impaired users by means of Hidden Markov Models, trained with relatively few examples is performed and reported. Different feature vectors are compared and the trade-off between accuracy and training set size is explored: an important issue for such interactively trained systems.

The use of cursor measures for motion-impaired computer users

“Point and click” interactions remain one of the key features of graphical user interfaces (GUIs). People with motion-impairments, however, can often have difficulty with accurate control of standard pointing devices. This paper discusses work that aims to reveal the nature of these difficulties through analyses that consider the cursor’s path of movement. A range of cursor measures was applied, and a number of them were found to be significant in capturing the differences between able-bodied users and motion-impaired users, as well as the differences between a haptic force feedback condition and a control condition. The cursor measures found in the literature, however, do not make up a comprehensive list, but provide a starting point for analysing cursor movements more completely. Six new cursor characteristics for motion-impaired users are introduced to capture aspects of cursor movement different from those already proposed.

Dasher: A Gesture-Driven Data Entry Interface for Mobile Computing

Existing devices for communicating information to computers are bulky, slow, or unreliable. Dasher is an interface incorporating language modeling and driven by continuous two-dimensional gestures (e.g., a mouse, a stylus, or eye-tracker). Tests have shown that, after 1 hr of practice, novice users reach a writing speed of about 20 words per minute (wpm) while taking dictation. Experienced users achieve writing speeds of about 34 wpm, compared with typical 10-finger keyboard typing of 40 to 60 wpm. Although the interface is slower than a conventional keyboard, it is simple to use and could be used on personal data assistants and by motion-impaired computer users. Dasher can readily be used to enter text from any alphabet.

Dasher: A Gesture-Driven Data Entry Interface for Mobile Computing

Existing devices for communicating information to computers are bulky, slow, or unreliable. Dasher is an interface incorporating language modeling and driven by continuous two-dimensional gestures (e.g., a mouse, a stylus, or eye-tracker). Tests have shown that, after 1 hr of practice, novice users reach a writing speed of about 20 words per minute (wpm) while taking dictation. Experienced users achieve writing speeds of about 34 wpm, compared with typical 10-finger keyboard typing of 40 to 60 wpm. Although the interface is slower than a conventional keyboard, it is simple to use and could be used on personal data assistants and by motion-impaired computer users. Dasher can readily be used to enter text from any alphabet.

Customised text entry devices for motor-impaired users

The standard QWERTY keyboard is the principal text entry device for word processing and computer-based communications. For many motor-impaired individuals, and in particular those without intelligible speech, the low text entry rates they can typically achieve is a major problem. For some, the QWERTY design is completely inappropriate. Alternative designs that can appreciably increase these rates would greatly enhance their ability to communicate. This paper considers and compares several approaches to the design of text entry devices for motor-impaired users. A general method for customising (i e, optimising) these designs is employed, and consideration is given to designs requiring significantly fewer input switches than the 26 or more keys required by QWERTY. Use is made of language statistics in the design procedure, and the increased availability of inexpensive, powerful computers is directly exploited.