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Gregg C. Vanderheiden, Ph.D.
John Mendenhall, B.S.
Trace R&D Center
University of Wisconsin-Madison
Keywords: Virtual Reality, Disability, Accessibility, Blindness, Impairment
In analyzing virtual reality applications to examine access issued for people with disabilities, it is useful to separate those applications where the virtual reality (VR) presentation is used as a metaphor from those where the mode of presentation is inherently tied to, or restricted by the information being presented. In the case where VR is being used only as a metaphor, it is often possible to provide access even to individuals with severe physical, cognitive, and sensory impairments by providing a display/control via an alternate mechanism in parallel with the VR metaphor. This type of parallel display/control strategy is not available when the presentation is inherently tied to the information being presented. For both types of applications, however, the application of virtual altered realities (VAR) can be used to either transpose or enhance the presentation of information in order to facilitate its perception and manipulation by people with varying physical, cognitive, and sensory abilities. This paper presents the strategies underlying these two approaches as well as providing examples of ways the strategies can be used to increase the accessibility and useability of virtual reality by people with disabilities.
In addressing the issues of access to any products or systems, one of the most basic approaches is to design the base product/system to be usable by people with a wide range of abilities thus circumventing the need for adapiation or assistive technologies for many people. This approach is particularly relevant to the development of future virtual reality systems, in two major ways. First, where VR is used as a metaphor it may be possible to fairly easily provide alternate physical or sensory metaphors if this flexibility is built into the base product. Second, the very nature of virtual reality and the ability to alter this constructed reality afford new opportunities for providing access to "the world as we find it." Basically, VR provides the opportunity to recreate a world or an environment to best match both the task at hand and the ability of the user.
Access to Metaphors
In examining the accessibility of virtual reality based applications by people with functional limitations (those who are elderly or who have disabilities), it is useful to separate those applications where the information being presented constrains the "virtual reality" which is used to present it from those applications where the format used to present the information or to allow its manipulation is chosen from among alternate presentation or control options. For example, one may have many ways of displaying volume level such as with a dial, bar, or printed or spoken number but one does not have a similar choice in presenting the Mona Lisa's smile. To help explore this distinction a two-class model is advanced.
The model presented here is an extension of the same model used to discuss graphical user interfaces (GUIs) (Vanderheiden, Andersen, Mendenhall, & Ford, 1992). In discussing the application of this model to virtual realities (VR), it is useful to draw parallels between the fairly mature technology of the GUIs and the still-developing technologies of VR. In this fashion, some of the access issues, as well as potential applications, can be highlighted. The two classes as they apply to graphical user interfaces are:
1) Class 1: information that is presented using graphic metaphors in the GUI, but which could also be presented in words. This includes text and visual metaphors for concepts that can be expressed verbally (e.g., a scroll bar, which could be replaced by a series of commands such as Page Up, Page Down, Set Position, etc., and an indicator of the individual's location within the overall document as a percentage). 2) Class 2: information which is inherently graphic and cannot be described easily and completely in words. Class 1 VR applications would similarly be those applications where either textual information is being presented, or where a three-dimensional VR metaphor is being used to present information which is not inherently 3D in nature, and could be expressed in words. Looking at the parallel between the graphical user interface and the virtual reality applications is useful here.
For instance, on the GUI, the iconic representation of the desktop with folders and files could also be handled with a hierarchical directory in a text format. The information itself is essentially verbal, and requires no visual component to effectively convey its meaning. This type of information is therefore categorized as Class 1, since it is inherently verbal in content, and no meaning is lost when interpreting these iconic representations verbally. Some users may find the visual metaphor easier to use, and some may find the verbal easier.
In a similar manner, Class 1 applications within VR would involve the use of virtual reality as an alternate way of presenting or manipulating information which could otherwise be presented in verbal fashion. Similar to the example from the GUI, the process of filing a document in virtual reality might involve using a 3D desktop with folders and file drawers. However, this function could also be handled as a hierarchical directory using text format and commands. As the VR technologies develop, some users may find it easier to interact with and manipulate some types of information using the virtual metaphors, just as many users of GUI find that a visual metaphor facilitates their carrying out some type of computer operations. However, this is not necessary (for class I information), and the information/manipulation could be handled other ways if a user were unable to use the VR metaphor.
The Class 2 applications would then be those applications which are not metaphorical, and which involve the presentation and manipulation of information which cannot be fully captured/presented in verbal form. For example, we might use the VR display to study the difference in laminar flow and turbulence near the wall of a tube. This would be an application of VR technology that could not be expressed verbally in a way that would convey the same information as is made available through the VR presentation. A second example involves the manipulation of molecules to study molecular forces. This is again distinctly VR in nature, and could not be accomplished or experienced in the same way through verbal commands and verbal feedback.
Drawing a distinction between these two types of VR applications (those which are metaphorical, and could be expressed through verbal commands and feedback, and those dependent upon the VR presentation format) is useful when considering the implications of VR for people with disabilities. In particular, it is useful to separate those applications of VR which will fall into Class 1. For individuals with disabilities which limit their ability to access some aspects of the virtual reality (e.g., individuals who are blind would be unable to access the visual component; individuals who are deaf would be unable to access the auditory component), alternate mechanisms for presenting the same information can be employed. For example, if the virtual reality display is being used to present some underlying concept in a 3D metaphor, individuals who are unable to access that metaphor may be able to access and control the underlying concepts through a different metaphor that does not involve the particular sense or ability which they lack.
The converse can also be true. For some disabilities, it may be that activities which are now carried out in verbal fashion (e.g., text) might be converted into a virtual reality metaphor, and thereby making the activities easier to understand. For instance, individuals with cognitive or language disabilities, who have difficulty dealing with systems involving verbal commands and verbal feedback, may find it easier to carry out the same commands when they are presented in a virtual reality made up of salient 3D metaphors.
Implications of the Ability to Alter Realities in VR Environments
In discussing the use of virtual reality applications by people with disabilities, it is also useful to make a distinction between virtual reality (VR) applications and applications which incorporate virtual altered realities (VAR). These two roles are often confused, and both have distinct roles to play in the lives of people with disabilities.
First, it is important to remember that everyone is a potential "person with a disability." In fact, people without disabilities are often referred to by those who have disabilities as "TABs" (Temporarily Able-Bodied) or as "CRABs" (Currently Regarded as Able-Bodied). It is therefore important that when we think of VR and people with disabilities, we think of it in three ways.
First, people with disabilities will find virtual reality technologies useful for all of the same purposes and for all of the same reasons as anyone else. Thus, the list of applications for people with disabilities begins with (and will be dominated by) the list of VR applications that one would think of if one were not considering the disability issue. The most important applications of VR for people with disabilities will most likely be the standard applications which they encounter in their education, employment, and daily living, rather than any applications designed especially for them. It will be much more important for them to be able to access and use "the world as they find it," which will include these virtual reality applications, than it will be that someone has developed some specialized application or tool for them.
Second, we should think of VR in conjunction with people with disabilities in terms of its flexibility or ability to be altered to better accommodate people with different skills or abilities. By the very nature of virtual reality, VR systems will be more plastic and lend themselves both to alternate designs and to designs which include alternatives for display and control.
Thirdly, VR can be thought of as a new tool which can be used to create special assistive technologies designed specifically to be used by and benefit people who have disabilities. In some cases, this will involve actual virtual reality based devices. In other cases, it will involve assistive technologies which use some of the components used in virtual reality systems (data gloves, etc.), but which are themselves not necessarily virtual reality systems.
Differentiating VR from VAR Applications
As discussed above, one of the applications for virtual reality systems is to provide the ability to create true virtual realities. For example, individuals who have difficulty in traveling would derive great benefit from being able to visit distant lands or participate in group conferences via telepresence. Individuals who might not have the motor abilities to participate safely in chemistry laboratories, etc., may be able to safely and effectively function in a virtual chemistry laboratory where momentary loss of motor control would be both benign and reversible. It may in fact be possible to back up to the point in time just before the accident and to continue activity from there. These alone could provide increased opportunities for exploration and participation over what is possible today.
A much more powerful application of this new technology, however, is not the ability to create virtual realities but the ability to create unrealities or altered realities (e.g., the ability not only to allow the individual with manipulation difficulties to operate in a simulated laboratory, but also to allow there to be handles on the flasks or enlarged controls on apparatus, or to allow people who are blind to observe color changes as changes in tone quality). In some cases, the virtualaltered reality would simply involve small changes in size or character of a particular aspect of the virtual reality. In other cases, it may involve a quite different mode for presentation of information or control in order to better match the abilities of the user.
A summary of different applications of virtual reality and virtual reality technologies in these different categories and across major disability groups is presented in Figure 1.
Application of VR with Different Types of Disabilities
To examine some of the different applications and implications of virtual reality for people with disabilities, let us take a quick overview of VR and VAR from the perspective of four major disability groups.
VR and Visual Impairment
Currently, the most highly developed aspect of virtual reality displays is the visual component. For individuals who are blind, this means that current virtual reality displays are of limited value. In those applications where the virtual reality is used simply as a metaphor (Class I), individuals who are blind could have access to the same systems if the underlying concepts being displayed and command structures required for operation were made available. Individuals who are blind could then use an auditory/tactile or other nonvisual mechanism to carry out the same tasks accomplished via the virtual reality visual interface. This would be similar to the provision of verbal access to the graphical user interfaces on modern computer systems.
Access to Class 2 applications or the Class 2 aspects of an application in virtual reality, however, would remain elusive as long as the virtual reality is dependent upon the visual display of information. As virtual realities add sound, touch, and force feedback, the value and accessibility of these environments for people who are blind will increase. Their access to these virtual realities would then approach their access to everyday reality (VR). Since the virtual reality is computer-generated, however, information such as color or visual texture could be presented verbally, or converted into tactually or auditorially discernible information to make it "visible" to the individual who is blind (VAR). In addition, other dimensions such as size could also be manipulated to increase accessibility of the information. For example, familiarizing themselves with the layout of a building might be accomplished by shrinking the building to a small size, which the individual could quickly explore with their hands. This can be much faster and more effective than walking around on the floor to get an orientation for corridor layout, etc. Similarly, detail on very small objects, which could be examined by sight or microscope but not fingertip, could easily be enlarged so that they became tactually distinct.
VAR could also be used to create special virtual guides, or to enhance objects tactually to facilitate their location. For example, individuals trying to locate an object could request that the object put out a taut string to the individual, which the individual could then follow back to the object. Similarly, the individual could request that an object be made larger or in some other way tactually distinct, and/or emit a sound, so that it could more easily be located.
Thus, although virtual realities currently threaten to create a larger gap between the abilities of people with sight and those without, it can also (as sound and tactile technologies are refined) provide new capabilities and opportunities for people who are blind to explore and manipulate things in their world.
Virtual Reality and Cognitive Impairments
Activities which are now carried out through verbal (text) commands and feedback may be much easier for people with cognitive or language impairments if they were rendered as virtual reality metaphors. For example, activities or devices which currently require the individual to react to information presented in written text (e.g., following the directions for cooking) might be easier if the instructions were presented as graphic sequences. They may be easier yet if the information is presented as actual three-dimensional representations, or if manipulation of the activities could be carried out through manipulation of three-dimensional metaphorical objects.
In addition, Class 2 applications of virtual reality could be used to help individuals with cognitive impairments by allowing them to practice in a less complex and more forgiving environment (for instance, developing skills associated with activities of daily living). Again, this would require that the virtual reality technology had achieved a very high degree of visual, tactile, and auditory reality. Once high fidelity VR is available, environments where mistakes are less catastrophic, and the overall stimuli are reduced, could be used to train individuals to carry out activities of daily living. Slowly, the environment could become more complex and realistic, bringing the individual to the point of being able to function safely and independently in the real world.
Finally, efforts to control the complexity of VR environments and to limit the "degrees of freedom" (Turvey, Fitch, & Tuller, 1982) in order to lower cognitive load for people with cognitive impairments may benefit all users of the system (Zeltzer 1992).
Virtual Reality and Hearing Impairment
Here, the use of visual metaphors for auditory events could be used both as an alternate presentation for auditory events and to help teach concepts, such as sound directionality, to individuals who are congenitally deaf. Individuals in virtual environments (or virtual environments which overlay real environments) could use new techniques to allow sound events to be presented visually (VAR). Visual sound waves emanating from a ringing phone, or sound arrows emanating from devices which are making noise provide salient information about 3D auditory sources. The shape, thickness, and color of the arrows could convey additional information regarding the sound character. These as well as other techniques for presenting sonic information visually could be used to provide access to people who are deaf or with severe hearing impairments within both Class 1 and Class 2 VR applications.
In addition to providing individuals who are deaf or with severe hearing impairments with access to regular VR applications, there are a number of specific applications which might be of particular benefit to people with hearing impairments. For example, the ability to have a fully animated cut-away view of an individual's mouth and throat could greatly facilitate the ability of an individual who is congenitally deaf to learn to speak, by observing the inner works of the oral cavity of others and/or themselves.
Virtual Reality and Physical Impairment
With regard to the presentation of information, individuals with physical impairments have all of the same sensory abilities to access and use virtual realities as individuals without physical impairments. The primary difficulty would involve their ability to manipulate the virtual objects. However, since the manipulation is actually being carried out through some sensing of the controlled movements of the user, it should be possible, using VAR, to allow individuals with physical disabilities to use alternate control sites or strategies to carry out the same manipulations. Thus, where an able-bodied individual would use their hand to reach out and pick up a virtual flask and pour out the contents, an individual who was paralyzed may be able to use a combination of head, mouth and facial movements to control the fingers of the virtual hand and carry out the same manipulations. Individuals who have movement, but who are very weak or who have restricted range of motion, could use a virtual environment to increase both their reach and their virtual strength in manipulating objects. In addition, the virtual environment provides everyone with the ability to move about, fly through the air, and otherwise maneuver within the virtual environments in ways which are unrelated to the physical constraints of our human bodies. When maneuvering by pointing one's hand, for example, it makes no difference whether one is sitting in an ordinary chair or a wheelchair. An individual can move about and manipulate objects within the virtual environment with the same ease.
Finally, as discussed above, individuals who, because of a physical disability or medical support systems, find it difficult to physically travel to conferences or for sightseeing may find that virtual realities and telepresence will allow them to more easily participate in virtual conferences and/or virtual travel.
From these discussions, it can be seen that virtual reality offers many opportunities. It is also clear that the use of virtual reality in education (simulated labs) and employment (virtual control and information system) could introduce new barriers (e.g., for people who are blind). In many cases, the barriers can be avoided or minimized if attention is directed toward them early on. Four areas that should be kept in mind as VR evolves are:
1) Where virtual reality is used as a metaphor, the underlying constructs should also be made available. Just as with graphical user interfaces, virtual reality metaphors are likely to appear
in computer or information systems of the future. As long as the underlying concepts being represented metaphorically are also available so that they can be presented in other forms (e.g., nonvisual forms for people who are blind, nonauditory for people who are deaf), access to these systems can be maintained. Similarly, commands or manipulations which are carried out through VR metaphors that require physical dexterity or eye-hand coordination should be executable via command or other mechanisms, to allow them to be accessed by individuals with physical impairments or with visual impairments, requiring an interface demanding less physical dexterity or eye-hand coordination.
2) As long as the VR environment is essentially visual, it will preclude participation by individuals who are blind. As sonic and tactile technologies are brought on-line, the accessibility of these environments to people with visual impairments can be greatly enhanced.
3) As these capabilities come on-line, it will be important to present information redundantly, using as many senses as possible, in order to facilitate the participation of users with mild and moderate, as well as severe, visual or hearing impairments.
4) Wherever possible, the opportunity to use VAR to present alternative representations of information or control should be explored. These alternatives may produce better interfaces for everyone, but are especially important for those experiencing functional limitations due to their abilities and/or the environment. Although the future VR environments will allow individuals to utilize all of their physical and sensory abilities, they tendency is to be biased toward individuals who have all of these abilities intact. Because the VR environment is artificial, however, it is also possible to provide sensory substitution or alternate physical control, in ways that would be very difficult or impossible in the real environment. This is especially true for Class I information. The extent to which this alternate sensory and physical presentation and control is possible with future virtual reality environments will be a function of how open the underlying structures of these Class I systems are, and how well they have been designed to support alternate presentation and manipulation interfaces.
Our experience with current graphical user interface suggests that unless these issues are raised early, the user interfaces will be optimized for individuals with full sensory and physical capabilities, and the ability to tap into the VR architectures at a level appropriate for using alternate access strategies will not exist except on a post-hoc or "patch" basis. Although virtual reality now appears to be something that will only be practical some time off in the future, experience has taught us that the future creeps up on us at ever-increasing rates. Now is the time to ensure that these basic concepts, and the importance of these alternate presentation and control strategies, are clearly seated in the awareness of those at the forefront of developing this new technology.
Figure 1- Connections Between Virtual Reality and Areas of Disability: Virtual Reality (VR)
Virtual Reality and Visual Impairments:
Virtual Reality and Cognitive Impairments:
Virtual Altered Reality (VAR), and Visual Impairments:
Virtual Altered Reality (VAR), and Hearing Impairments:
Virtual Altered Reality (VAR), and Physical Impairments:
Virtual Altered Reality (VAR), and Cognitive Impairments:
Use of VR Components in Assistive Technologies, and Hearing Impairments:
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