Goal Crossing with Mice and Trackballs for People with Motor Impairments

Accuracy and Reliability of At-home Quantification of Motor Impairments Using a Computer-based Pointing Task with Children with Ataxia-Telangiectasia

Methods for obtaining accurate quantitative assessments of motor impairments are essential in accessibility research, design of adaptive ability-based assistive technologies, as well as in clinical care and medical research. Currently, such assessments are typically performed in controlled laboratory or clinical settings under professional supervision. Emerging approaches for collecting data in unsupervised settings have been shown to produce valid data when aggregated over large populations, but it is not yet established if in unsupervised settings measures of research or clinical significance can be collected accurately and reliably for individuals. We conducted a study with 13 children with ataxia-telangiectasia and 9 healthy children to analyze the validity, test-retest reliability, and acceptability of at-home use of a recent active digital phenotyping system, called Hevelius. Hevelius produces 32 measures derived from the movement trajectories of the mouse cursor, and it produces a quantitative estimate of motor impairment in the dominant arm using the dominant arm component of the Brief Ataxia Rating Scale (BARS). The severity score estimates generated by Hevelius from single at-home sessions deviated from clinician-assigned BARS scores more than the severity score estimates generated from single sessions conducted under researcher supervision. However, taking a median of as few as 2 consecutive sessions produced severity score estimates that were as accurate or better than the estimates produced from single supervised sessions. Further, aggregating as few as 2 consecutive sessions resulted in good test-retest reliability (ICC = 0.81 for A-T participants). This work demonstrated the feasibility of performing accurate and reliable quantitative assessments of individual motor impairments in the dominant arm through tasks performed at home without supervision by the researchers. Further work is needed, however, to assess how broadly these results generalize.

Effects of cursor freeze time on the performance of older adult users on mouse-related tasks

This study determines the optimum range of cursor freeze time (CFT) for basic target acquisition tasks. The effect of five levels of CFT was measured on double-clicking, clicking, and drag-and-drop operations, along with the inconvenience perceived by users at these levels. Older adult users find these standard mouse operations challenging because of slipping and accidental cursor movement. In this study, 24 older adult participants (13 males and 11 females) performed the abovementioned tasks repeatedly across five levels of CFT (0, 200, 400, 600, and 800 ms) and rated their perceived inconvenience at each level. CFT was found to have a significant effect on the three basic target acquisition tasks as well as the inconvenience perceived by participants. Performance on the drag-and-drop task was negatively influenced when the CFT was increased from 600 to 800 ms. The analysis suggests that a CFT of 200-400 ms is the optimum range for improved performance on the tasks.

Wireless sEMG-Based Body-Machine Interface for Assistive Technology Devices

Assistive technology (AT) tools and appliances are being more and more widely used and developed worldwide to improve the autonomy of people living with disabilities and ease the interaction with their environment. This paper describes an intuitive and wireless surface electromyography (sEMG) based body-machine interface for AT tools. Spinal cord injuries at C5-C8 levels affect patients' arms, forearms, hands, and fingers control. Thus, using classical AT control interfaces (keypads, joysticks, etc.) is often difficult or impossible. The proposed system reads the AT users' residual functional capacities through their sEMG activity, and converts them into appropriate commands using a threshold-based control algorithm. It has proven to be suitable as a control alternative for assistive devices and has been tested with the JACO arm, an articulated assistive device of which the vocation is to help people living with upper-body disabilities in their daily life activities. The wireless prototype, the architecture of which is based on a 3-channel sEMG measurement system and a 915-MHz wireless transceiver built around a low-power microcontroller, uses low-cost off-the-shelf commercial components. The embedded controller is compared with JACO's regular joystick-based interface, using combinations of forearm, pectoral, masseter, and trapeze muscles. The measured index of performance values is 0.88, 0.51, and 0.41 bits/s, respectively, for correlation coefficients with the Fitt's model of 0.75, 0.85, and 0.67. These results demonstrate that the proposed controller offers an attractive alternative to conventional interfaces, such as joystick devices, for upper-body disabled people using ATs such as JACO.

Empirical evaluation of circling interface with head-mounted mouse emulator users

PURPOSE

To evaluate the performance of the circling interface, which is an alternative interaction method for selecting and manipulating on-screen objects based on circling the target, rather than pointing and clicking.

METHOD

We conducted empirical evaluations with actual head-mounted mouse emulator users from two different groups: individuals with spinal cord injury (SCI) and individuals with cerebral palsy (CP), comparing each group's performance and satisfaction level on pointing tasks with the circling interface to performance on the same tasks when using dwell-clicking software.

RESULTS

Across all operations, for both subjects with SCI and with CP, the circling interface showed faster performance than the dwell-clicking interface. For the single-click operation, the circling interface showed slower performance than dwell selection, but for both double-click and drag-and-drop operations, the circling interface produced faster performance. Subjects with CP required much longer time to complete the tasks compared to subjects with SCI. If errors caused by circling on an area with no target and unintentional circling caused by jerky movements and an abnormally tiny circle are automatically corrected by the circling interface, their performance accuracy with the circling interface outperformed existing solutions without a steep learning curve.

CONCLUSIONS

Circling interface can be used in conjunction with existing techniques and this kind of combined approach achieve more effective mouse use for some individuals with pointing problems. It is also expected to be useful for both computer access and augmentative communication software. Implications for Rehabilitation A circling interface will improve clinical practice by providing an alternative pointing method that does not require physically activating mouse buttons and is more efficient than dwell-clicking. Being used in conjunction with existing techniques, some individuals who are head mouse users can achieve more effective mouse use. The Circling interface can also work with AAC devices.

Circling motion and screen edges as an alternative input method for on-screen target manipulation

PURPOSE

To investigate a new alternative interaction method, called circling interface, for manipulating on-screen objects. To specify a target, the user makes a circling motion around the target. To specify a desired pointing command with the circling interface, each edge of the screen is used. The user selects a command before circling the target.

METHOD

To evaluate the circling interface, we conducted an experiment with 16 participants, comparing the performance on pointing tasks with different combinations of selection method (circling interface, physical mouse and dwelling interface) and input device (normal computer mouse, head pointer and joystick mouse emulator).

RESULTS

A circling interface is compatible with many types of pointing devices, not requiring physical activation of mouse buttons, and is more efficient than dwell-clicking. Across all common pointing operations, the circling interface had a tendency to produce faster performance with a head-mounted mouse emulator than with a joystick mouse. The performance accuracy of the circling interface outperformed the dwelling interface.

CONCLUSIONS

It was demonstrated that the circling interface has the potential as another alternative pointing method for selecting and manipulating objects in a graphical user interface. Implications for Rehabilitation A circling interface will improve clinical practice by providing an alternative pointing method that does not require physically activating mouse buttons and is more efficient than dwell-clicking. The Circling interface can also work with AAC devices.

Fuzzy Adjustment Control in Command Evaluation Platform

OBJECTIVE

For motor handicapped persons, the use of computer interface devices could be a challenging task. Two research venues have been explored to address the usability problem for handicapped users of computer systems. In the first, the focus is on development of new peripheral devices to accommodate the needs of such users. The second venue, which is the focus of this article, addresses the development of efficient rehabilitation algorithms that can adapt existing interface devices to commands from handicapped users. The main goal of this article is to analyze the existing software adaptation platform PLatform to Evaluate ICT for Assistance with a focus on evaluating and enhancing the use of pointing devices for increased adaptation to interface commands.

SUBJECTS AND METHODS

In the first part of this article, a new quantitative analysis approach is presented, which is useful to occupational therapists in choosing among existing information and communication technologies. We define quantification indicators to be used in the analysis of a person's movements. The proposed indicators would be classified in two categories: Task indicators and adaption indicators. In the second part of the article, we present a fuzzy rehabilitation complementary module that adapts the user command without the need to adjust the interface device. The subject is a quadriplegic 12-year-old boy. The test was conducted using five attempts after a brief description and a small demonstration of the experiment. The test was rerun the second day for another five attempts.

RESULTS

The subject could not command the joystick in the left direction without a customized device. With a customized device, he was able to control properly the mouse cursor on the screen.

CONCLUSIONS

The adaptation technique used in this work helped the subject to properly control the computer pointing device. The evaluation technique helped assess the subject and give the proper parameters to the adaptation algorithm.

Investigating Grid-Based Navigation

Hands-free speech-based technology can be a useful alternative for individuals that find traditional input devices, such as keyboard and mouse, difficult to use. Various speech-based navigation techniques have been examined, and several are available in commercial software applications. Among these alternatives, grid-based navigation has demonstrated both potential and limitations. In this article, we discuss an empirical study that assessed the efficacy of two enhancements to grid-based navigation: magnification and fine-tuning. The magnification capability enlarges the selected region when it becomes sufficiently small, making it easier to see the target and cursor. The fine-tuning capability allows users to move the cursor short distances to position the cursor over the target. The study involved one group of participants with physical disabilities, an age-matched group of participants without disabilities, and a third group that included young adults without disabilities. The results confirm that both magnification and fine-tuning significantly improved the participants’ performance when selecting targets, especially small targets. Providing either, or both, of the proposed enhancements substantially reduced the gaps in performance due to disability and age. The results will inform the design of speech-based target selection mechanism, allowing users to select targets faster while making fewer errors.

The Development and Evaluation of Performance-Based Functional Assessment

Understanding and describing the physical capabilities of users with motor impairments is a significant challenge for accessibility researchers and system designers alike. Current practice is to use descriptors such as medical diagnoses to represent a person’s physical capabilities. This solution is not adequate due to similarities in functional capabilities between diagnoses as well as differences in capabilities within a diagnosis. An alternative is user self-reporting or observation by another person, but these solutions can be problematic because they rely on individual interpretations of capabilities and may introduce unwanted bias. The current research focuses on defining an objective, quantifiable, repeatable, and efficient methodology for assessing an individual’s physical capabilities in relation to use of information technologies. Thirty-one users with a range of physical capabilities participated in the evaluation of the proposed performance-based functional assessment methodology. Building on the current standard for such assessments, multiple observers provided independent assessments that served as the gold standard for comparison. Promising metrics produced through the performance-based assessment were identified through comparisons with these observer evaluations. Predictive models were then generated via regression and correlation analysis. The models were validated using a three-fold validation process. Results from this initial research are encouraging, with the resulting models explaining up to 92% of the variance in user capabilities. Directions for future research are discussed.