Glossary

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Visual Evoked Potential(also: VEP, Visually Evoked Response, VERP)

A visual evoked potential (VEP) is an electrical signal generated by the brain's visual cortex in response to a visual stimulus, typically a flash of light or a pattern change. VEPs are measured using electrodes placed over the occipital lobe and extracted from background EEG…

Visual Expression(also: Visual Self-Expression)

The use of visual media — including photography, graphic design, social media posts, presentations, and art — to communicate identity, mood, intent, and personal style. Visual expression goes beyond functional content to encompass aesthetic choices like color palettes, filters,…

Visual Fatigue(also: Eye Strain, Asthenopia, Visual Strain)

Discomfort, tiredness, or reduced visual performance resulting from prolonged or intensive visual tasks. For people with low vision, visual fatigue can occur more quickly because they must exert greater effort to see, often using non-optimal parts of their retina (eccentric…

Visual Feedback(also: Visual Biofeedback)

A method of providing real-time visual information to a user about their actions, performance, or physiological state. In speech therapy and assistive technology, visual feedback systems display graphical representations of vocal output to help users understand and modify their…

Visual Fidelity(also: Graphical Fidelity, VF)

The degree to which a virtual environment replicates the visual detail, realism, and complexity of real-world settings. In accessibility contexts, visual fidelity affects cognitive load and task performance differently across user populations. Research shows that individuals…

Visual Field(also: Field of Vision)

The total area visible to a person when their eyes are fixated on a central point, including both central and peripheral vision. Visual field can be measured in degrees and is assessed through perimetry testing. Various eye conditions affect the visual field differently:…

Visual Field Loss(also: Visual Field Deficit, VFL, Field Loss)

A reduction in the area of vision that a person can see without moving their eyes or head. Visual field loss can affect any portion of the visual field — central, peripheral, or specific quadrants — and can result from conditions affecting the eyes (glaucoma, retinal detachment)…

Visual Fragmentation(also: Visual Grouping, Visually Fragmented Grouping)

The design practice of organizing web page content into distinct visual groups using layout techniques such as background colors, tables, spacing, horizontal lines, and borders. Sighted users perceive these groupings at a glance and understand their roles (navigation, main…

Visual Grounding(also: Grounded Visual Understanding)

The ability of an AI model to connect its language output to specific elements actually present in the visual input, ensuring that descriptions and responses are anchored to real objects and scenes rather than generated from learned patterns or assumptions. Poor visual grounding…

Visual Hallucination(also: AI hallucination, MLLM hallucination)

In the context of multimodal AI systems, visual hallucination refers to the generation of descriptions or responses that contain information not grounded in the actual visual input—fabricating non-existent objects, misattributing properties such as colour or size, or…

Visual Impairment(also: Vision Impairment, Low Vision, Sight Loss)

A reduction in the ability to see that cannot be fully corrected with standard glasses, contact lenses, or medical treatment. Visual impairments range from low vision (partial sight) to total blindness and include conditions like macular degeneration, glaucoma, diabetic…

Visual Inertial Odometry(also: VIO)

A motion tracking technique that combines camera-based visual tracking with inertial sensor data (gyroscopes and accelerometers) to estimate a device’s position and orientation in 3D space with high accuracy. VIO works by tracking salient visual features across consecutive video…

Visual Information Seeking Mantra(also: Overview First, Shneiderman's Mantra)

A design principle for information visualisation coined by Ben Shneiderman, summarised as "overview first, zoom and filter, then details-on-demand." The mantra describes an optimal pattern for presenting complex information: start with a broad overview so users can orient…

Visual Interpretation(also: AI Visual Interpretation, Visual Interpretation Application)

The task of translating visual content — a scene, object, document, interface, or image — into a form accessible to a blind or low-vision user, typically spoken or written description, answers to questions, or actionable guidance. Visual interpretation systems may be…

Visual Interpretation Service(also: VIS, Visual Assistance Service, Remote Sighted Assistance)

A service that provides visual information to blind and low vision users through human assistants, AI-powered tools, or a combination of both. Traditional visual interpretation services like Aira connect users via video call to trained human agents who describe visual…

Visual Interpretation Services(also: VIS, Remote Sighted Assistance, Visual Assistance Services)

Visual interpretation services are technology platforms that connect blind and low vision users with sighted assistants (either human volunteers or paid professionals) who provide real-time visual descriptions through video calls or image sharing. Services like Aira and Be My…

Visual Interpreter(also: Visual Interpreter Service, Visual Description Service, VIDS)

A visual interpreter or description service (VIDS) is a technology or human-powered service that provides people who are blind or have low vision with descriptions of their visual surroundings, typically by receiving camera feeds from the user's smartphone or smart glasses.…

Visual Language(also: Visuo-Gestural Language)

A language that uses the visual-gestural modality for communication, as opposed to the auditory-vocal modality of spoken languages. Sign languages are visual languages that encode information through hand shapes, movements, spatial relationships, facial expressions, and body…

Visual Language Model(also: VLM, Vision-Language Model)

AI models that can process and reason about both visual and textual information, combining computer vision with large language model capabilities. VLMs could potentially enhance assessment descriptors by providing contextually rich and customizable descriptions of visual…

Visual Layout Analysis(also: Layout Analysis, Document Layout Analysis)

The automated process of examining the spatial arrangement and visual properties of elements within a document to infer meaningful structural relationships between them. In accessibility contexts, visual layout analysis is used to automatically generate metadata about how…

Visual Layout Customization(also: Layout Customization, Video Layout Arrangement)

The ability for users to rearrange, resize, reposition, lock, or remove visual elements in a digital interface to suit their individual needs. In videoconferencing, visual layout customization is critical for d/Deaf and hard of hearing users, who may need to enlarge the…

Visual Literacy

The ability to interpret, evaluate, and create visual messages and content. Visual literacy encompasses understanding visual conventions (like color symbolism, composition rules, and typographic hierarchies), evaluating the aesthetic quality and effectiveness of visual…

Visual Orchestration(also: Visual Attention Management)

A design orientation, articulated by Huffman et al. (2026), for deliberately coordinating visual cues, salience, timing, and layout so that participants in a shared environment know where to look, when to shift focus, and how interactions unfold — especially for users who rely…

Visual Perception(also: Visual Processing)

The brain's ability to interpret and organize visual information, including recognizing shapes, distinguishing between similar forms, perceiving spatial relationships, and processing symmetry. In accessibility contexts, differences in visual perception are relevant to dyslexia…

Visual Presentation(also: Text Presentation)

The way text and content are visually rendered on screen or in print, encompassing typography, layout, color, spacing, and formatting choices. Visual presentation significantly affects readability and accessibility for all users but is especially critical for people with…

Visual Privacy(also: Visual Information Privacy)

The safeguarding and management of sensitive visual information that could be shared or disclosed in everyday life, particularly through the use of assistive technologies and generative AI tools. For blind and low vision users, visual privacy encompasses multiple dimensions:…

Visual Processing(also: Visual Processing Disorder, Visual Perception)

The brain's ability to interpret and make sense of visual information received through the eyes. Visual processing difficulties can affect reading, spatial awareness, figure-ground discrimination, and the ability to process complex visual layouts, even when visual acuity is…

Visual Profile(also: Visual Function Profile)

A visual profile is a comprehensive characterization of an individual's visual capabilities across multiple dimensions, typically including visual acuity, contrast sensitivity, visual field, and color perception. In accessibility, understanding a user's visual profile is…

Visual Programming(also: Visual Programming Language, Block-Based Programming)

A programming paradigm that allows users to create programs by manipulating graphical elements — such as blocks, nodes, and connecting paths — rather than writing text-based code. Popular examples include Scratch, LabVIEW, and dataflow systems where blocks represent…

Visual Prompts(also: Picture Prompts, Visual Cues, Photographic Cues)

Images, icons, photographs, or other visual representations used to guide, remind, or support individuals in completing tasks, following schedules, or navigating environments. Visual prompts are particularly important for people with cognitive disabilities, intellectual…

Visual Prosthetic(also: Visual Prosthesis, Vision Prosthetic)

A device or system that provides visual information to people who are blind or have severe visual impairments through alternative sensory channels or direct neural stimulation. Visual prosthetics range from smartphone apps that convert visual data into audio or haptic feedback…

Visual Question Answering(also: VQA)

A task in which a system receives an image and a natural language question about that image, then generates a natural language answer. VQA emerged as a key accessibility paradigm through services like VizWiz, where blind users could submit photos with questions and receive…

Visual Saliency(also: Saliency Detection, Visual Attention Prediction)

A computer vision concept referring to the degree to which visual elements attract attention compared to their surroundings. Saliency detection models predict which parts of an image or video frame will draw the viewer eye first, based on factors like contrast, color, motion,…

Visual Saliency(also: Saliency, Saliency Detection, Saliency Map)

A computational measure of how much a particular region of an image or video stands out from its surroundings and attracts visual attention. Saliency models predict where people are most likely to look based on factors such as contrast, colour, motion, and semantic content. In…

Visual Scene Display(also: VSD)

A type of augmentative and alternative communication (AAC) layout that uses photographs or images of real-world scenes with embedded interactive hotspots that produce speech output when selected. Unlike grid displays that present abstract symbols in rows and columns, VSDs ground…

Visual Schedule(also: Picture Schedule, Activity Schedule)

A visual representation of a sequence of activities or steps that an individual is expected to complete, using pictures, symbols, photographs, or written words arranged in chronological order. Visual schedules are widely used in educational and therapeutic settings for autistic…

Visual Search Strategy(also: Scanning Strategy, Visual Scanning)

Systematic approaches to visually exploring an environment or scene to locate specific objects, patterns, or information. In low-vision rehabilitation, therapists train clients in efficient search strategies such as systematic scanning patterns (horizontal, vertical, spiral),…

Visual Skimming(also: Visual Scanning, Page Scanning)

The rapid visual process of scanning a page to quickly identify relevant content, key information, and areas of interest without reading every word. Sighted users can typically assess a webpage's relevance in about five seconds through visual skimming, guided by visual…

Visual Speech Aid(also: Speech Reading Aid, Visual Communication Aid)

A visual speech aid is an assistive device or system that converts auditory speech information into visual form to help individuals with hearing impairments follow spoken conversation. These aids may display text (as in captioning systems), phonetic symbols, lip-shape cues,…

Visual Stress Syndrome(also: Meares-Irlen Syndrome, Irlen Syndrome, Scotopic Sensitivity Syndrome)

A perceptual processing condition characterized by symptoms of visual distortion, discomfort, and fatigue when reading text, particularly black text on white backgrounds. Individuals with visual stress syndrome experience distortions such as letters appearing to move, merge, or…

Visual Supports(also: Visual Aids, Visual Cues)

Pictures, symbols, photographs, written words, objects, or other visual items used to support communication, learning, and behaviour in individuals with developmental disabilities, particularly autism. Visual supports leverage the strong visual processing abilities common among…

Visual Verification(also: Visual Fact-Checking)

The process of confirming the accuracy of information by visually inspecting the original source material. In accessibility contexts, visual verification represents a fundamental challenge for blind and low vision users who cannot directly compare AI-generated descriptions…

Visual Vernacular(also: VV)

A deeply visual sign language performance art form rooted in visual storytelling, developed in the 1970s by deaf American actor Bernard Bragg and widely practiced internationally. Visual Vernacular combines gesture, facial expression, classifiers, body movement, and cinematic…

Visual Vocabulary(also: Picture-Based Vocabulary, Icon Vocabulary)

A collection of words or concepts represented through images, icons, or pictorial symbols rather than text alone. Visual vocabularies are widely used in augmentative and alternative communication (AAC) systems to support people who have difficulty with text-based language,…

Visual acuity(also: VA, LogMAR acuity, Snellen acuity)

A measure of the sharpness or clarity of vision, typically expressed as a Snellen fraction (e.g., 20/20, 20/200) or LogMAR value. A person with 20/200 vision must be 20 feet away to see what someone with normal vision sees at 200 feet. Visual acuity of 20/200 or worse in the…

Visual assistance technology(also: VAT, AI visual assistance, Visual interpretation service)

Technology that uses artificial intelligence, computer vision, or human volunteers to provide visual information to blind and low-vision users. Examples include apps like Seeing AI, Be My Eyes, and Lookout, which can identify objects, read text, describe scenes, and recognise…

Visual authoring(also: Visual content creation)

The process of creating or editing visual content such as images, graphics, videos, or layouts. Visual authoring has traditionally been one of the least accessible creative activities for blind and low vision users because it requires real-time visual feedback to evaluate and…

Visual design space

The physical medium related to human sight through which a user and device may interact. The visual design space is the dominant channel in most user interfaces, encompassing text, images, video, colour, layout, animation, and spatial arrangement. The overwhelming bias toward…

Visual dispersion(also: Visual splitting, Divided visual attention)

The cognitive challenge faced by deaf and hard of hearing people when they must simultaneously monitor multiple visual information sources, such as an instructor, presentation slides, a sign language interpreter or captions, and their own notes. Because deaf individuals receive…

Visual field loss(also: Peripheral vision loss, Scotoma, Tunnel vision)

A reduction in the area of vision that a person can see, either in the periphery (peripheral vision loss or tunnel vision) or in the center (central vision loss or central scotoma). Visual field loss is caused by conditions such as glaucoma, retinitis pigmentosa, stroke, and…