Accessibility of Virtual Reality
Making Virtual Reality Systems Accessible to Users with Disabilities
Issues and Opportunities Identified in the Literature
It is clear from our review of the literature that some of the accessibility issues raised in connection with virtual environments are already addressed by Web Content Accessibility Guidelines 2.0 or are likely to be addressed in version 2.1. Specifically, concerns about the difficulty of holding down keys on a keyboard in order to issue a command (e.g., to move an avatar, where the distance moved depends on the duration of the key press) would be overcome by implementing WCAG 2.0, success criterion 2.1.1, with its exclusion of keyboard interfaces “requiring specific timings for individual keystrokes”.
However, the remapping of keys used to control virtual environments is not currently required by WCAG. It is nevertheless noted in the literature as desirable.
The contrast of graphical objects and of user interface components is proposed to be the subject of requirements in WCAG 2.1. Traditional screen magnifiers could be used with VR applications. However, for the screen magnifier user, there remains the problem of becoming oriented to the virtual environment and of locating, then moving to, objects of interest.
Alternative input devices that can simulate keystrokes or pointer actions should also be usable, subject to the remarks above regarding timing of keyboard input.
The question of how best to make VR systems more accessible to people with learning and cognitive disabilities remains largely unexplored by researchers. However, the educational benefits of virtual environments to learners with significant cognitive disabilities have been found to be substantial.
The challenge of making VR applications non-visually accessible is much discussed in the literature. A central difficulty noted by researchers lies in the potentially overwhelming amount of visual information that can, in principle, be extracted from VR systems and conveyed to the user, with a consequent need to be selective in what is provided and to support interactive exploration and navigation operations that offer the user control of the information presented.
Means of non-visual access documented in the literature include the following.
- The use of sensory substitution devices to provide somewhat direct access to visual content. These however have the disadvantage of being challenging to learn to use correctly.
- The provision of speech and non-speech audio directly within the VR system to prvide a non-visual interface.
- Construction of a specialized VR client application that interacts with the underlying virtual world using high-level protocols/APIs, and which offers a purely textual mode of interaction for the screen reader user.
- The provision of specific commands within the VR environment (e.g., to go directly to a specified location or to follow another user) which assist with non-visual navigation.
- The use of virtual assistive technologies (e.g., white cane via a haptic device, if I recall correctly) to provide non-visual feedback – see category 2.
Significant Issues Not Discussed in the Literature Reviewed
Substantive accessibility issues raised by WebVR specialists for consideration by the Accessible Platform Architectures Working Group are not reflected in the literature reviewed by this Task Force. Specifically, some applications of virtual reality may require the user to perform movements (e.g., turning one's body) that are typical of interactions with the physical environment, but which are not typical of conventional human/computer interfaces. There is an important question regarding what features (e.g., alternative means of control) VR applications should support to meet the needs of people with physical disabilities for whom performing such actions is difficult or infeasible. More generally, support for a variety of input mechanisms (each with different demands) is essential to good accessibility. Further, it seems reasonable to hold that those who can use a given input device, but subject to limitations, should be supported in doing so where this is likely to be effective. For example, a user who has a constrained range of motion could nevertheless be supported by the design of virtual environments in carrying out interactions by ensuring that the movements required by the user interface fall within the individual's physical limits.
An example of this challenge discussed in a meeting of the APA Working Group occurs where a person in a chair cannot reach a virtual object (i.e., cannot perform the reaching action to the height demanded by the user interface of the VR application). The VR system could respond to this access need by increasing the height of the virtual floor in order to change the required reaching action so that it can be performed by the user, thus allowing the virtual object to be manipulated via a user interface gesture that nevertheless mirrors the action that would be performed to touch a corresponding real object. Thus, the virtual environment can be modified to address access needs in ways that the real environment, in general, cannot be.
The Use of "Virtual" Accessibility Devices
In the consideration of VR interaction and navigation mechanisms for people with disabilities, it is important to assess the value of using simulated real-world aids in a VR environment.
An initial focus on how people with disabilities could be supported in VR revolved around the Second Life environment. While the default interface was considered largely inaccessible, it emerged that multi-user virtual environments could enable users to transcend physiological or cognitive challenges to great social and therapeutic benefit. Examples included haptic input devices for blind users, virtual regions developed according to Universal Design principles, communities dedicated to people with cognitive-related disabilities, the use of the avatar as counsellor, and customizable personae that either transcend or represent a disabled person's self-identity(Smith, 2012). The haptic interfaces in particular led to the consideration as to how real-world aids such as a white cane or a wheelchair could be used to provide a similar, familiar support mechanism in VR that matched its real-world equivalent.
A more recent example of physical aids being made into virtual ones is showcased in research relating to the use of a virtual white cane. The research identified that if the same audio cues associated with a real-world infrared white cane were used in VR, users were able to effectively centre themselves in the middle of pathways and walk successfully through virtual doorways based on the same audio feedback as used n the equivalent real-world device (Maidenbaum & Amedi,2015).
This approach demonstrates that in addition to the use of assistive technologies currently available on computers and mobile devices, simulation of physical aids are also likely to be beneficial and their availability should be considered as a part of future VR projects.
Simulation of Disability in Virtual Reality
An important primary use of VR in a disability context relates to the simulation of a disability within a virtual environment. Applications for the simulation of disability include rehabilitation of an acquired disability, preparation for people with disabilities to interact with a new environment and as a training mechanism for people to learn about a particular type of disability.
Initial work in the area of simulation of a disability in VR commenced in the early 1990s whereby a proof-of-concept based on sensing gloves was used to diagnose and train patients post hand surgery. Other researchers pioneered the use of virtual environments in phobias, attention deficit, post-traumatic stress and other conditions. In 1996 researchers interested primarily in VR phobia treatment started the Cybertheory conference series, and VR-based physical therapy, occupational therapy, therapy for learning deficits, and amnesia were reported at the first International Conference on Disability, Virtual Reality and Associated Technologies (Burdea, 2009).
While the early examples of VR simulation bare little resemblance to the immersive environments now available, the move towards a more autonomous delivery of e-health services has seen a number of recent innovative ways on how people with disabilities can be supported through the use of VR. For example, a computer-assisted motivational neurorehabilitation framework has been designed and implemented. Focused particularly on supporting people recovering from stroke-related injuries, the system integrates support for a suite of standard-compliant computer input devices, including force-reflecting joysticks and driving wheels as physical therapeutic interfaces along with support for a suite of personalize and remotely tenable goal-directed performance assessment and motivational interventional exercise protocols, including features like data archive, management, and analysis tools. The system also provides support for personalized VR user interfaces that are tuned to the abilities and preferences of the user while also supporting emerging user interface and remote access standards. (Feng, 2007). As a result of VR, medical staff were able to effectively monitor and determine the likelihood of a stroke occurring (Feng, 2007).
As VR solutions have continued to become more immersive and affordable, the use of disability simulation in a rehabilitation context has moved beyond monitoring and includes more focus on the completion of everyday tasks. This is often achieved by a combination of VR and robotics to provide support to people with disabilities moving around in a simulated environment (Hakim, Tunis, & Ross, 2017) Such features allow for environmental conditions to be simulated in practical ways such as practicing the use of a wheelchair in VR by adjusting the perspective of the user from a standing to a sitting position and simulating the speed of movement.
While the use of VR to simulate an environment for a person with a disability is effective, it can also be useful as a training mechanism for people that need to learn about disability-related scenarios. In particular, medical staff and other industry professionals that are not familiar with the experience of a particular disability can significantly benefit by experiencing a simulated disability and associated environmental interaction in VR (Forczek, Makra, Lanyi, & Bari, 2015) The use of VR in this context enables people to provide improved support to people with disabilities by learning about their need and gaining a deeper insight through a simulated disability experience. This use of VR can also extend to the workplace whereby a simulated environment can help to prepare a person with a disability for entering a particular job or to learn new ways to interact with an office environment (Jansari, Agnew, Akesson, & Murphy, 2004).
In essence, the specific recommendations for VR simulation in a disability and rehabilitation context can largely be categorised into two fundamentally important requirements: The first is to ensure that accessibility is considered as a mechanism to provide therapeutic benefit to the person with a disability immersed in VR, the second is to provide information about their disability to the person with a disability, such as in an e-health context (Forczek et al., 2015). Furthermore, provisions may need to be considered as to how best to provide a standardised experience to people using VR as a mechanism to understand disability that is not based on their own experience.
- Burdea, G. C. (2009). Rubber ball to cloud rehabilitation musing on the future of therapy (pp. 50-50).
- Feng, X. (2007). Upper-extremity performance assessment using an interactive, personalized computer-assisted neurorehabilitation motivating framework. In J. M. Winters (Ed.): ProQuest Dissertations Publishing.
- Folmer, E., Yuan, B., Carr, D., & Sapre, M. (2009, October). TextSL: a command-based virtual world interface for the visually impaired. In Proceedings of the 11th international ACM SIGACCESS conference on Computers and accessibility (pp. 59-66). ACM.
- Forczek, E., Makra, P., Lanyi, C., & Bari, F. (2015). The Internet as a New Tool in the Rehabilitation Process of Patients-Education in Focus. International Journal of Environmental Research and Public Health, 12(3), 2373-2391.
- Hakim, R. M., Tunis, B. G., & Ross, M. D. (2017). Rehabilitation robotics for the upper extremity: review with new directions for orthopaedic disorders (Vol. 12, pp. 765-771): Taylor & Francis.
- Jansari, A., Agnew, R., Akesson, K., & Murphy, L. (2004). The Use of Virtual Reality to Assess and Predict Real-world Executive Dysfunction: Can VR Help for Work-placement Rehabilitation? Brain Impairment, 5(1), 110.
- Kruger, R., & van Zijl, L. (2014, March). Rendering virtual worlds in audio and text. In Proceedings of International Workshop on Massively Multiuser Virtual Environments (pp. 1-2). ACM.
- Maidenbaum, S., Chebat, D. R., Levy-Tzedek, S., & Amedi, A. (2014, April). Vision-deprived virtual navigation patterns using depth cues & the effect of extended sensory range. In CHI'14 Extended Abstracts on Human Factors in Computing Systems (pp. 1231-1236). ACM.
- Maidenbaum, S., & Amedi, A. (2015, March). Non-visual virtual interaction: Can Sensory Substitution generically increase the accessibility of Graphical virtual reality to the blind?. In Virtual and Augmented Assistive Technology (VAAT), 2015 3rd IEEE VR International Workshop on (pp. 15-17). IEEE.
- Oktay, B., & Folmer, E. (2010, April). Synthesizing meaningful feedback for exploring virtual worlds using a screen reader. In CHI'10 Extended Abstracts on Human Factors in Computing Systems (pp. 4165-4170). ACM.
- Smith, K. (2012). Universal life: the use of virtual worlds among people with disabilities. Universal Access in the Information Society, 11(4), 387-398.
- Standen, P. J., & Brown, D. J. (2006). Virtual reality and its role in removing the barriers that turn cognitive impairments into intellectual disability. Virtual Reality, 10(3-4), 241-252.
- Trewin, S., Laff, M., Hanson, V., & Cavender, A. (2009). Exploring visual and motor accessibility in navigating a virtual world. ACM Transactions on Accessible Computing (TACCESS), 2(2), 11.