1.Introduction
XR is an acronym used to refer to the spectrum of hardware, applications, and techniques used for virtual reality or immersive environments, augmented or mixed reality and other related technologies. This document is developed as part of a discovery into accessibility related user needs and requirements forXR. This document does not represent a formal working group position, nor does it currently represent a set of technical requirements that a developer or designer need strictly follow. It aims to outline the diversity of some current accessibility related user needs inXR and what potential requirements to meet those needs may be.
1.1What does the term 'XR' mean?
As with theWebXR API spec and as indicated in the relatedWebXR explainer, this document uses the acronymXR to refer to the spectrum of hardware, applications, and techniques used for virtual reality or immersive environments, augmented or mixed reality and other related technologies. Examples include, but are not limited to:
- Immersive or augmented environments used for education, gaming, multimedia, 360° content and other applications.
- Head mounted displays, whether they are opaque, transparent, or utilise video passthrough.
- Mobile devices with positional tracking.
- Fixed displays with head tracking capabilities.
The important commonality between them being that they all offer some degree of spatial tracking with which to simulate a view of virtual content as well as navigation and interaction with the objects within these environments.
Terms like "XR Device", "XR Application", etc. are generally understood to apply to any of the above. Portions of this document that only apply to a subset of these devices will be indicated as appropriate.
1.2Definitions of virtual reality and immersive environments
Virtual reality and immersive environment definitions vary but converge on the notion of immersive computer-mediated experiences. They involve interaction with objects, people and environments using a range of controls. These experiences are often multi-sensory and may be used for educational, therapeutic or entertainment purposes.
1.3Definitions of augmented and mixed reality
Augmented and mixed reality definitions vary but converge on the notion of computer-mediated interactions involving overlays on the real world. These may be informational, or interactive depending on the application.
UnderstandingXR itself presents various challenges that are technical. They include issues with a range of hardware, software and authoring tools. To make accessibleXR experiences there is a need to understand interaction design principles, accessibility semantics and assistive technologies. However, these all represent 'basic' complexities that are in themselves substantial. To add to this, for many designers and authors they may neither know nor have access to people with disabilities for usability testing. Neither may they have a practical way of understanding accessibility related user needs that they can build a solid set of requirements from. In short, they just may not understand what user needs they are trying to meet.
Some of the issues inXR, for example in gaming, for people with disabilities include:
- Over emphasis on motion controls. There are many motion controllers that emphasise using your body to control the experience. Some games withXR components may lock out traditional control methods when a VR headset is being used, and the user should always be able to use a range of input mechanisms.
- VR Headsets need the user to be a physical position to play. The user should not have to be in a particular physical position such as standing or sitting to play a game or perform some action. Or there should be ability to remap these 'physical positions' to other controls (such as usingWalkinVRDriver).
- Games and hardware being locked to certain manufacturers. Consoles should allow full button remapping on standard game controllers - to different types of assistive technologies such as switches. These remapping preferences should be mobile, and transportable across a range of hardware devices and software.
- Gamification of VR forces game dynamics on the user. Some users may wish to just explore an immersive environment without the 'game'.
- Audio design lacks spatial accuracy. Sound design needs particular attention and can be critical for a good user experience for people with disabilities. The auditory experience of a game or other immersive environment may 'be' the experience [able-gamers].
There are a range of disabilities that will need to be considered in makingXR accessible. It is beyond the scope of this document to describe them all in detail. General categories or types of disabilities are:
- Auditory disabilities
- Cognitive disabilities
- Neurological disabilities
- Physical disabilities
- Speech disabilities
- Visual disabilities
A person may have one of these disabilities or a combination of several. User needs are presented here that may relate to several of these disabilities with a range of requirements that should be met by the author or the platform. ForXR designers and authors understanding these needs is crucial when makingXR environments accessible.
Some things designers and authors need to be aware of:
- Understanding specific diverse user needs and how they relate toXR.
- Successfully identifying modality needs that are not obvious - but still need to be supported.
- Suitable authoring tools that support accessibility requirements inXR.
- Using languages, platforms and engines that support accessibility semantics.
- Providing accessible alternatives for content and interaction.
- 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 navigation to support different modalities.
- The use of virtual assistive technologies (e.g., white cane via a haptic device) to provide non-visual feedback. The research identified that if the same audio cues associated with a real-world infrared white cane were used in immersive environment, 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 in the equivalent real-world device [maidenbaum-amendi]
3.1Immersive Environment challenges
Some of the challenges within immersive environments (and gaming) accessibility include the use of extremely complex input devices, control schemes that require a high degree of precision, timing and simultaneous action; ability to distinguish subtle differences in busy visual and audio information, having to juggle multiple complex goals and objectives [web-adapt].
There are also currently very useful accessibility guidelines available that are specific to gaming [game-a11y].
3.3Various input modalities
The following are example of some of the diverse input methods used by people with disabilities. In many real-world applications these input methods may be combined.
3.4Various output modalities
The following are a list of outputs that can be available to a user to help them understand, interact with and 'sense' feedback from anXR application. Some of these are in common use on the Web and other exploratory (such as Olfactory and Gustatory.)
- Tactile - this is using the sense of touch, or commonly referred to as haptics.
- Visual - this is using the sense of sight, such as 2D and 3D graphics.
- Auditory - this is using the sense of sound, such as rich spatial audio, surround sound.
- Olfactory - this is the sense of smell.
- Gustatory - this is the sense of taste.
3.6Customization of control inputs
Give the user the ability to modify their input preference or use a variety of input devices. The remapping of keys used to control movement or interaction in virtual environments is not currently required by WCAG. It is nevertheless noted in the literature as desirable.
3.7 Using multiple diverse inputs simultaneously
A user with a disability may have several input devices or different assistive technologies. A user may switch 'mode' of interaction, or the tools used without degrading the user experience where they lose focus on a task and cannot return to it, or make unwanted input.
Complexity needs to be managed and co-ordinated between different kinds of assistive technology in immersive environments. There is a platform level requirement to support multiple assistive technologies in a cohesive manner. This would allow combinations to be used in a co-ordinated way e.g. where the users day-to-day AT, can be used with other AT that may be embedded in the environment already for example.
Note
The REQ 5b: Voice activation also indicates potential issues with pairing multiple devices via Bluetooth.
3.8Consistent tracking with multiple inputs
There may be tracking issues when switching input devices. A tracking issue is where the user may lose their focus or it can be modified in unpredictable or unwanted ways, this can cause loss of focus and potentially push the user to make unwanted inputs or choices.
Outputs sent to multiple devices will need to be synchronised.
This document outlines various accessibility related user needs forXR. These user needs should drive accessibility requirements forXR and its related architecture. These come from people with disabilities who use assistive technologies and wish to see the features described available withinXR enabled applications.
User needs and requirements are often dependent on context of use. The following outline some accessibility user needs and requirements that may be applicable in immersive environments, augmented reality and 360° applications.
These following are neither exhaustive, nor definitive but are presented to help orientate the reader towards understanding some broad user needs and how to meet them.
4.1Immersive semantics and customization
- User Need 1: A user of assistive technology wants to navigate, identify locations, objects and interact within an immersive environment.
- REQ 1a: Navigation mechanisms must be intuitive with robust affordances. Navigation, location and object descriptions must be accurate and identified in a way that is understood by assistive technology.
- REQ 1b: Controls need to support alternative mapping, rearranging of position, resizing and sensitivity adjustment.
- REQ 1c: Objects that are important within any given context of time and place can be identified in a suitable modality.
- REQ 1d: Allow the user to filter or sort objects and content.
- REQ 1e: Allow the user to query objects and content for more details.
Note
In an spatialized augmented reality environment a blind user may find a combination of text to speech and sonic symbols helpful. By using a combination of text to speech and sonic symbolism a blind user can do a self-guided tour of a given area using their smartphone. [spatialized-navigation]
4.2Motion agnostic interactions
- User Need 2: A person with a physical disability may want to interact with items in an immersive environment in a way that doesn't require particular bodily movement to perform any given action.
- REQ 2a: Allow the user performing an action in the environment, in a device independent way, without having to do so physically.
- REQ 2b: Ensure that all areas of the user interface can be accessed using the same input method.
- REQ 2c: Allow multiple input methods to be used at the same time.
Note
There are accessibility issues specific to augmented reality. For example, the user may be expected to scan the environment, or scan physical objects, to determine the placement of virtual objects. The user may need to mark a location or an area in space so that the AR application can generate appropriate virtual objects. The user should be able to perform these actions in a motion agnostic way.
4.3Immersive personalization
- User Need 3: Users with cognitive and learning disabilities may need to personalize the immersive experience in various ways.
- REQ 3a: Support Symbol sets so they can be used to communicate and layered over objects and items to convey affordances or other needed information in way that can be understood according to user preference.
- REQ 3b: Allow the user to turn off or 'mute' non-critical environmental content such as animations, visual or audio content, or non-critical messaging.
4.4Interaction and target customization
- User Need 4: A user with limited mobility, or users with tunnel or peripheral vision may need a larger 'Target size' for a button or other controls.
- REQ 4a: Ensure fine motion control is not needed to activate an input.
- REQ 4b: Ensure hit targets are large enough with suitable spacing around them.
- REQ 4c: Ensure multiple actions or gestures are not required at the same time to perform any action.
- REQ 4d: Support 'Sticky Keys' requirements such as serialization for various inputs when the user needs to press multiple buttons.
4.5Voice commands
- User Need 5: A user with limited mobility may want to be able to use Voice Commands within the immersive environment, to navigate, interact and communicate with others.
- REQ 5a: Ensure Navigation and interaction can be controlled by Voice Activation.
- REQ 5b: Voice activation should preferably use native screen readers or voice assistants rather than external devices to eliminate the additional step needed to pair devices.
4.6Color changes
- User Need 6: Color blind users may need to be able to customise the colors used in the immersive environment. This will help with understanding affordances of various controls or where color is used to signify danger or permission.
- REQ 6a: Provide customised high contrast skins for the environment to suit luminosity and color contrast requirements.
4.7Magnification context and resetting
- User Need 7: Screen magnification users may need to be able to check the context of their view in immersive environments.
- REQ 7a: Allow the screen magnification user to check the context of their view and track/reset focus as needed.
- REQ 7b: Where it makes sense (such as in menus) interface elements can be enlarged and the menu reflowed to enhance the usability of the interface up to a certain magnification requirement.
Note
There are customisation approaches such as the automatic generation of user interfaces as demonstrated in the SUPPLE project, which adapt to the different challenges the user may face, such as vision, motor control and other user preferences and abilities. A generated UI can make multiple adaptations for different user needs at the same time. This is achieved by generating a UI, or several - after testing a person's ability using an algorithm to learn their preferences. [supple-project]
4.8Critical messaging and alerts
- User Need 8: Screen magnification users may need to be made aware of critical messaging and alerts in immersive environments often without losing focus. They may also need to route these messages to a 'second screen' (seeREQ 14 Second Screen).
- REQ 8a: Ensure that critical messaging, or alerts have priority roles that can be understood and flagged to AT, without moving focus.
4.9Gestural interfaces and interactions
- User Need 9: A blind user may wish to interact with a gestural interface, such as a virtual menu system.
- REQ 9a: Support touch screen accessibility gestures (e.g. swipes, flicks and single, double or triple taps with 1, 2 or 3 fingers). SeeREQ 14 Second Screen.
- REQ 9b: Using a virtual menu system - enable a self-voicing option and have each category, or item description, spoken as they receive focus via a gesture or other input. As the blind user gestures to trigger both movement and interaction they may get more detail about items that are closer to them. The user must be allowed to query and interrogate these items and make selections.
- REQ 9c: Allow for the re-mapping of gestures to associate different actions with different input types or gestures. This may be a virtual switch that can map to new macros on the fly. This will allow the user to change defaults and employ gestures to carry out new actions offered by the immersive environment as required.
4.10Signing videos and text description transformation
- User Need 10: A deaf or hard of hearing person, for whom a written language may not be their first language, may prefer signing of video for text, objects or item descriptions.
- REQ 10a: Allow text, objects or item descriptions to be presented to the user via a signing avatar (pre-recorded only).
- REQ 10b: Any signing videos should be 1/3rd minimum of the original streams signing size. This requirement comes from research of 240 ASL videos intended to be watched by deaf signers,that found that nearly all set signer size to at least one-third the size of the full video. [raja-asl]
4.11Safe harbour controls
- User Need 11: People with Cognitive Impairments may be easily overwhelmed in Immersive Environments.
- REQ 11a: Allow the user to set a 'safe place' - quick key, shortcut or macro.
4.12Immersive time limits
- User Need 12: Users may be adversely affected by spending too much time in an immersive environment or experience, and may lose track of time.
- REQ 12a: Provide a platform integration with tools that support digital wellbeing, allow the user to access alarms for time limits during an immersive session.
4.13Orientation and navigation
- User Need 13: A screen magnification user or user with a cognitive and learning disability or spatial orientation impairment needs to maintain focus and understand where they are in immersive environments.
- REQ 13a: Ensure the user can reset and calibrate their orientation/view in a device independent way.
- REQ 13b: Ensure field of view in Immersive environments, are appropriate, and can be personalized - so users are not disorientated.
- REQ 13c: Provide clear visual or audio landmarks.
4.14Second screen devices
- User Need 14: Users of assistive technology such as a blind, or deaf-blind users communicating via a RTC application inXR, may have sophisticated 'routing' requirements for various inputs and outputs and the need to manage same.
- REQ 14a: Allow the user to route text output, alerts, environment sounds or audio to a braille or other second screen device.
- REQ 14b: Ensure that the user can manage the flow of critical messaging, or content to display on a second screen.
- REQ 14c: Support touch screen accessibility gestures (e.g. swipes, flicks and single, double or triple taps with 1, 2 or 3 fingers) on a second screen device to allow the user to navigate menus and interact.
Note
'Second screen' is a term used in this document to denote any another external output device, such as a monitor or sound card, or assistive technology such as braille output. The use of the term is not restricted to just these devices and can refer to any output device a user may choose.
4.15Interaction speed
- User Need 15: Users with physical disabilities or cognitive and learning disabilities may find some interactions too fast to keep up with or maintain.
- REQ 15a: Allow users to change the speed they can travel or perform interactions, in an immersive environment.
- REQ 15b: Allow timings for interactions or critical inputs to be modified or extended.
- REQ 15c: Provide help for the user with a cognitive or learning disability.
- REQ 15d: Provide clear start and stop mechanisms.
Note
The term 'help' for REQ 15c may vary from explanatory information such as textual/symbolic annotations in an application, to human assistance in real time.
4.16Avoiding sickness triggers
- User Need 16: Users with vestibular disorders, Epilepsy, and photo sensitivity may find some interactions trigger motion sickness and other affects. This may be triggered when doing teleportation or other movements inXR.
- REQ 16a: Avoid interactions that trigger epilepsy or motion sickness and provide alternatives.
- REQ 16b: Ensure flickering images are at a minimum, will not trigger seizures (more than 3 times a second), or can be turned off or reduced.
4.17Spatial audio tracks and alternatives
- User Need 17: Hard of hearing users may need accommodations to perceive audio.
- REQ 17a: Provide spatialized audio content to emulate three-dimensional sound forms in immersive environments.
- REQ 17b: Provide text descriptions of important audio content.
4.18Spatial orientation: Mono audio option
- User Need 18: Users with spatial orientation impairments, cognitive impairments or hearing loss in just one ear may miss information in a stereo or binaural soundscape.
- REQ 18a: Allow mono audio sound to be sent to both headphones so that the user can perceive the whole soundscape through either ear. [mono-ios].
Note
People with traumatic brain injuries can have a range of impairments. These may be spatial orientation impairments, auditory processing difficulties, visual processing difficulties or a combination. They may miss information in stereo or binaural soundscapes. This can affect orientation while navigating. Even if provided with accurate directions, they may not recognize surroundings, or experience anxiety when navigating.
4.19Captioning, Subtitling and Text: Support and customization
A.Change Log
The following is a list of new requirements and other changes in this document:
- Immersive semantics and customization: REQ 1c: Objects that are important within any given context of time and place can be identified in a suitable modality.
- Immersive semantics and customization: REQ 1d: Allow filtering and the ability to query items and content for more details.
- REQ 1e: Allow the user to query objects and content for more details.
- Mono audio option: REQ 19a: Allow mono audio sound to be sent to both headphones so that the user can perceive the whole soundscape through either ear. [mono-ios]
- Interaction and target customization: REQ 4d: Support 'Sticky Keys' requirements such as serialization for various inputs when the user needs to press multiple buttons.
- Gestural interfaces and interactions REQ 9a: Support touch screen accessibility gestures (e.g. swipes, flicks and single, double or triple taps with 1, 2 or 3 fingers).
- Magnification context and resettingREQ 7b: Where it makes sense (such as in menus) interface elements can be enlarged and the menu reflowed to enhance the usability of the interface up to a certain magnification requirement.
- Gestural interfaces and interactionsREQ 9a: Support touch screen accessibility gestures (e.g. swipes, flicks and single, double or triple taps with 1, 2 or 3 fingers) on a second screen device to navigate menus and interact.
- Gestural interfaces and interactionsREQ 9c: Allow for the re-mapping of gestures to associate different actions with different input types or gestures. This may be a virtual switch that can map to new macros on the fly. This will allow the user to change defaults and employ gestures to carry out new actions offered by the immersive environment as required.
- Signing videos and text description transformation REQ 10b: Any signing videos should be 1/3rd minimum of the original streams signing size. This requirement comes from research of 240 ASL videos intended to be watched by deaf signers, that found that nearly all set signer size to at least one-third the size of the full video.
- Orientation and navigation REQ 13c: Provide clear visual or audio landmarks.
- Second screen devicesREQ 14b: Ensure that the user can manage the flow of critical messaging, or content to display on a second screen.
- Second screen REQ 14c: Support touch screen accessibility gestures (e.g. swipes, flicks and single, double or triple taps with 1, 2 or 3 fingers) on a second screen device to allow the user to navigate menus and interact.
- Spatial audio tracks and alternatives REQ 17b: Provide text descriptions of important audio content.
Requirements have been updated based on combined review feedback, discussion and Research Questions Task Force consensus. Other user needs have been edited to better reference related requirements such as with Second screen devices.
Various clarification or reference notes have been added relating to:
- The importance of discoverability relating to accessibility features inXR.
- Specific augmented reality issues when marking locations in a motion agnostic way.
- W3C Personalization semantics and how they can support people with cognitive impairments.
- The need for accessibility API's that map custom user interface actions to control types.
- The limitations of accurate live interpretation via a digital signing avatar.
- The impact of traumatic brain injury on a user's spatial orientation, auditory and visual processing abilities.