Glossary

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VBraille(also: V-Braille, Vibration Braille)

A method for representing Braille characters on a smartphone touchscreen using vibration feedback. The screen is divided into a 3-row by 2-column grid matching a standard Braille cell layout, and the phone vibrates when the user touches regions corresponding to raised dots in…

VQA(also: Visual Question Answering)

VQA (Visual Question Answering) is an AI task in which a system answers natural-language questions about the content of an image. In assistive contexts, VQA systems such as Be My AI, Seeing AI, and Aira let blind and low-vision users ask about their visual surroundings - from…

VR Accessibility Training(also: Virtual Reality Training for Accessibility, VR-Based AT Training)

The use of virtual reality environments to teach people with disabilities how to use assistive technologies or navigate unfamiliar real-world scenarios in a safe, controlled setting. VR training allows users to practice spatial and physical skills — such as aiming a smartphone…

Variable Friction(also: Variable Friction Display, Friction Modulation)

A surface haptics technique that dynamically adjusts the friction between a user's fingertip and a touchscreen surface to create the sensation of different textures. Typically achieved through ultrasonic vibration that creates a thin cushion of air beneath the fingertip,…

Variable Pointing Performance(also: Variable Pointing Ability, Intermittent Pointing Difficulty)

A condition where a person's ability to accurately use a pointing device (such as a mouse, trackpad, or touchscreen) fluctuates over time due to factors like physical impairments, fatigue, medication effects, aging, or environmental conditions. Unlike permanent severe motor…

Verbosity(also: Verbosity Level, Screen Reader Verbosity)

Verbosity refers to the level of detail that an assistive technology — particularly a screen reader or voice browser — provides when announcing interface elements and content. Most screen readers allow users to adjust verbosity settings to control how much contextual information…

Verbosity Level(also: Verbosity Setting, Detail Level)

A configurable setting that controls the amount of detail provided in text or audio descriptions of content, particularly for screen reader users and accessible data visualizations. Verbosity levels typically range from low (minimal summary with key points only) to high…

Verbosity Settings(also: Screen Reader Verbosity, Announcement Settings)

Configuration options that control the amount of detail a screen reader or accessible application announces to the user. Verbosity settings allow users to adjust the balance between receiving comprehensive information and reducing auditory noise. In development environments,…

Verification loop(also: Feedback loop, Edit-verify cycle)

An interaction pattern in which a user performs an action, receives feedback about the result, evaluates whether the outcome matches their intent, and decides whether to accept, undo, or refine the action. In non-visual accessibility contexts, verification loops are essential…

Vibration Feedback(also: Haptic vibration, Vibrotactile feedback)

The use of controlled vibration patterns — varying in duration, interval, intensity, and spatial location — to convey information to a user through the sense of touch. In assistive technology for blind people, vibration feedback has two advantages over audio feedback: it does…

Vibro-Audio(also: Vibrotactile Audio, Vibro-Tactile)

Vibro-audio is a multimodal interaction technique that combines vibration feedback from a device's built-in motor with auditory cues to convey information non-visually. On touchscreen devices, vibro-audio enables users to explore graphical content through touch — the device…

Vibro-Audio Map(also: VAM, Vibro-Audio Display)

A multimodal map representation for touchscreen devices that combines vibrotactile feedback with synchronised audio cues to convey spatial information non-visually. Users explore the map by dragging a finger across the screen; when they cross a feature (a street, a room…

Vibro-audio Interface(also: VAI)

An assistive technology that combines vibration patterns and audio feedback to convey spatial and graphical information through touchscreen devices. Originally developed to make maps and diagrams accessible to people who are blind, VAIs can render shapes, routes, and directional…

Vibromotor(also: Vibration Motor, Vibrotactile Actuator, ERM)

A vibromotor is a small motor that produces vibration, commonly used in haptic feedback devices, smartphones, and wearable technology. The most common types are eccentric rotating mass (ERM) motors, which spin an off-center weight, and linear resonant actuators (LRAs), which…

Vibrotactile(also: Vibrotactile Feedback, Vibrotactile Stimulation)

A form of tactile feedback that uses mechanical vibrations applied to the skin to convey information. Vibrotactile stimulation typically operates at frequencies between 10-500 Hz and is perceived through mechanoreceptors in the skin. In assistive technology, vibrotactile…

Vibrotactile Feedback(also: VTF, Vibration Feedback)

A form of haptic feedback that communicates information through vibration patterns delivered to the skin, typically via small motors embedded in wearable devices such as armbands, gloves, or watches. Vibrotactile feedback offers an alternative sensory channel for conveying…

Vibrotactile Feedback(also: Vibrotactile, Vibrotactile Display, Tactile Vibration)

A form of haptic feedback that uses vibration patterns to convey information through the sense of touch. In accessibility, vibrotactile feedback provides an alternative or complement to visual and auditory output channels, enabling communication with users who are blind, deaf,…

Vibrotactile feedback(also: Tactile vibration, Haptic vibration)

A form of haptic feedback that uses mechanical vibrations applied to the skin to convey information through the sense of touch. Vibrotactile actuators can communicate directional cues, alerts, patterns, and intensity levels without relying on vision or hearing. In accessibility…

Video Conferencing(also: Videoconferencing, Video Teleconferencing, Video Call)

Real-time visual and audio communication between two or more people at different locations using video cameras, displays, and network connections. Video conferencing has significant accessibility implications: for Deaf and hard-of-hearing sign language users, it must provide…

Video Conferencing Accessibility(also: Virtual Meeting Accessibility, Online Meeting Accessibility)

The design and implementation of video conferencing platforms to be usable by people with disabilities, including those using screen readers, keyboard-only navigation, captions, and other assistive technologies. Key accessibility considerations include clear screen reader…

Video Customization(also: Video Personalization, Adaptive Video)

The ability for viewers to modify the visual and auditory presentation of video content to suit their individual needs and preferences. Video customization for accessibility can include adjusting layout (removing or emphasizing visual elements), modifying backgrounds, changing…

Video Enrichment(also: Enriched Video, Video Augmentation)

The process of augmenting video content with additional elements such as captions, audio descriptions, images, audio cues, hyperlinks, or tactile outputs to make it more accessible or informative for different audiences. Unlike traditional approaches where added elements are…

Video Magnifier(also: CCTV Magnifier, Electronic Magnifier, Desktop Video Magnifier)

An assistive device that uses a camera to capture and display magnified images of printed material, objects, or other visual content on a screen. Video magnifiers range from portable handheld units to desktop models with large monitors. For musicians with low vision, handheld…

Video Phone(also: Videophone, VP)

A telecommunications device that enables real-time video and audio communication between two or more parties. For Deaf and hard of hearing people, video phones are essential communication tools that allow conversation in sign language over distance, providing functional…

Video Prompting(also: Video-based prompting, Step-by-step video instruction)

An instructional technique that uses short video clips to show a person with a developmental or intellectual disability how to complete individual steps of a task, presented one step at a time. Unlike video modeling (which shows the entire task performed continuously), video…

Video Remote Interpreting(also: VRI)

A fee-based service that provides sign language interpretation via video conferencing technology, where the interpreter is located remotely rather than physically present with the deaf and hearing participants. VRI is commonly used when two of the three parties (the deaf person,…

Video See-Through(also: VST, Video Pass-Through)

A type of head-mounted display architecture where the user perceives the real world through camera feeds displayed on screens inside the headset, rather than looking directly through transparent lenses. Video see-through systems like the Apple Vision Pro capture the environment…

Video modeling(also: Video-based modeling, Video self-modeling)

An evidence-based instructional strategy that uses video recordings to demonstrate target behaviors, social skills, or task sequences, which the viewer then imitates. For children with autism, video modeling leverages often-strong visual processing abilities to teach social…

Video relay service(also: VRS)

A telecommunications service that enables deaf and hard-of-hearing sign language users to communicate with hearing people via telephone through a video link with a sign language interpreter. The deaf caller signs to the interpreter via video, and the interpreter speaks to the…

Video see-through(also: VST, Camera passthrough)

A display approach in head-mounted devices where the user's view of the real world is captured by outward-facing cameras and displayed on screens inside the headset, allowing complete digital manipulation of the visual feed before presentation. For low vision users, video…

Video-Based Sign Language Dictionary(also: Video Sign Dictionary, Sign Language Video Lookup)

A digital dictionary that allows users to look up sign language signs by submitting video of themselves performing the sign, rather than searching by text or linguistic features. These systems use sign language recognition technology to match the user's input against a database…

Videoconferencing Accessibility(also: Virtual Meeting Accessibility)

The extent to which videoconferencing platforms like Zoom, Microsoft Teams, and Google Meet can be used effectively by people with disabilities. Key accessibility concerns include screen reader compatibility with meeting controls and features, captioning for deaf and hard of…

Virtual Acoustic Environment(also: Audio Virtual Environment, Acoustic Virtual Environment)

A computer-generated environment that uses audio as the primary medium for representing spaces, objects, and interactions, enabling users to navigate and interact with a virtual world through sound. Virtual acoustic environments are particularly valuable for blind users,…

Virtual Cursor(also: Browse Mode Cursor, Virtual PC Cursor)

A navigation mechanism used by screen readers that creates a linearized, text-based representation of a web page through which users can move sequentially. Unlike a visual cursor that points to a location on screen, the virtual cursor moves through the page's content structure —…

Virtual Exploration(also: Virtual Navigation, Virtual Travel)

The use of technology to simulate the experience of navigating or exploring a real-world environment without physically being there. For people with visual impairments, virtual exploration typically relies on audio-based representations of geographic data — including spatial…

Virtual Human(also: Embodied Agent, Animated Character)

A computer-generated human character used in accessibility applications to convey information through human-like movements, gestures, and expressions. In sign language accessibility, virtual humans serve as signing avatars that can automatically translate text or speech into…

Virtual Keyboard(also: On-screen keyboard, Soft keyboard, OSK)

A software-rendered keyboard displayed on screen that allows users to input text by clicking, tapping, or hovering over virtual keys using a mouse, trackball, touchscreen, eye tracker, or other pointing device. Virtual keyboards are essential assistive technology for people with…

Virtual Peer(also: VP, Virtual Agent, Animated Conversational Agent)

A computer-animated character designed to simulate peer interaction, typically used in educational or therapeutic settings. Virtual peers can engage in conversation, model social behaviors, and provide a lower-stakes environment for practicing social skills compared to human…

Virtual Reality(also: VR)

An immersive technology that creates a fully computer-generated environment, replacing the user's view of the real world with a simulated one. VR is typically experienced through a head-mounted display that tracks head and body movements to update the virtual scene in real time.…

Virtual Reality(also: VR, Immersive Virtual Environment)

A computer-generated simulation of a three-dimensional environment that users can interact with using specialized hardware such as headsets, motion controllers, or body tracking sensors. In accessibility contexts, virtual reality offers potential benefits for training and…

Virtual Signing(also: Avatar Signing, Synthetic Signing)

Virtual signing is the use of computer-generated animated characters (avatars) to present sign language, as an alternative to pre-recorded video of human signers. Virtual signing systems typically involve motion capture of human signers to create sign dictionaries, sign language…

Virtual Tour(also: 3D Virtual Tour, Digital Walkthrough)

A digital replica of a physical environment, typically captured using 360-degree cameras and depth sensors, that allows users to remotely explore and navigate through a space in a semi-immersive experience. In accessibility contexts, virtual tours offer people with mobility…

Virtual World Accessibility(also: Metaverse Accessibility, VR Accessibility for Blind Users)

Virtual world accessibility refers to the design and implementation of techniques that enable people with disabilities, particularly blind and visually impaired users, to participate in 3D virtual environments such as online virtual worlds, VR platforms, and metaverse…

Virtual reality(also: VR, Immersive virtual environment)

A computer-generated simulation of a three-dimensional environment that users can interact with using specialized hardware such as head-mounted displays and motion controllers. Virtual reality presents significant accessibility challenges because most VR applications rely…

Viseme(also: Visual Phoneme)

The visual equivalent of a phoneme — the distinct mouth shape or lip position that corresponds to a speech sound as seen on a speaker's face. Unlike phonemes, which are auditory units, visemes are visual units that represent how the mouth looks during speech production. Multiple…

Vision Language Model(also: VLM, Vision-Language Model, Multimodal Large Language Model)

A machine-learning model trained to take both images and natural-language text as input and to produce natural-language output. Modern VLMs — such as GPT-4o, Gemini, and Claude — can describe a photo, read text inside an image, answer questions about a scene, identify objects,…

Vision Multiplexing(also: Visual Multiplexing)

An optical engineering concept for low-vision aids that involves presenting multiple views or visual channels simultaneously to compensate for reduced visual function. In the context of assistive technology, vision multiplexing allows users to see both a wide field of view and a…

Vision-Language Model(also: VLM, Multimodal AI Model, Large Multimodal Model)

An artificial intelligence model that can process and reason about both visual (image/video) and textual information simultaneously. Vision-language models like GPT-4o, Claude, and Gemini can describe images, answer questions about visual content, and generate text based on…

Visual Access Technology(also: Visual Assistance Technology, Visual Access Tools)

Technologies that help blind and low vision people understand visual content in both digital and physical environments. Traditional visual access technologies include screen readers, magnification software, and human-powered description services (like Be My Eyes with volunteer…

Visual Assistance Technology(also: VAT, Visual Aid App)

Mobile applications and devices that take videos or images as input and provide verbal, haptic, or other non-visual output to help blind and low vision people access visual information. VAT can be human-enabled (e.g., Be My Eyes, Aira) where remote sighted volunteers or agents…