Glossary

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Color Gamut(also: Colour Gamut, Gamut)

The complete range of colours that can be represented or reproduced by a particular colour space, display device, or visual system. In the context of colour vision, a trichromat's gamut encompasses the full range of colours perceivable by typical human vision, while a…

Color Histogram(also: Colour histogram, Histogram tracking)

A statistical summary of the distribution of colour values across the pixels of an image or image region, often computed in a perceptual colour space such as Lab. In assistive computer-vision systems for blind users, colour histograms are used to re-identify and track a specific…

Color Identifier(also: Color Detector, Color Recognition Device)

A color identifier is an assistive technology device or application that detects and announces the color of objects for people with vision impairments. Standalone hardware devices use a light sensor pressed against an object to identify its color and speak the result aloud.…

Color Perception(also: Color Vision, Chromatic Vision)

Color perception is the ability to detect, distinguish, and identify colors. Impairments in color perception range from complete color blindness (achromatopsia) to partial deficiencies in distinguishing specific color ranges, such as red-green or blue-yellow color vision…

Color Sonification(also: Colour Sonification, Color-Audio Encoding)

The process of translating colour information into audible sound signals, enabling people who are blind or have visual impairments to perceive colour through hearing. Color sonification systems typically map different colour properties (such as hue, saturation, and luminosity)…

Color Space(also: Colour Space, Color Model)

A mathematical model that describes the range of colours that can be represented as numerical values, typically using three or more coordinates. Common colour spaces include RGB (red, green, blue), used in digital displays; CMYK (cyan, magenta, yellow, key/black), used in…

Color Theory(also: Colour Theory)

A body of principles and guidelines for understanding how colors interact, combine, and affect perception. In accessibility contexts, color theory is important for ensuring sufficient contrast ratios, avoiding color-only information encoding, and designing for color vision…

Color Universal Design(also: CUD, Colour Universal Design)

A set of guidelines and principles developed to ensure that colour use in designs, products, and environments is accessible to people with all types of colour vision, including those with colour vision deficiency. Color Universal Design emphasizes selecting colour palettes that…

Color Vision Deficiency(also: Color Blindness, CVD, Colour Blindness)

A condition in which a person has difficulty distinguishing between certain colors, most commonly red and green (deuteranopia/protanopia), but also blue and yellow (tritanopia) or all colors (achromatopsia). Color vision deficiency affects approximately 8% of males and 0.5% of…

Colorism(also: Skin Tone Bias, Shadeism)

Colorism is a form of discrimination in which people are treated differently based on the shade of their skin tone, typically favoring lighter skin over darker skin within and across racial groups. In digital accessibility, colorism is relevant to image descriptions and AI…

Colour Commentary(also: Color Commentary, Colour commentator)

In sports broadcasting, the analytical and contextual commentary provided alongside the play-by-play — offering opinions, background on players and teams, strategy discussion, and remarks during gameplay pauses. Colour commentary conveys information that is not visually present…

Colour Contrast(also: Color Contrast, Contrast Ratio)

The measurable difference in luminance or colour between two adjacent elements, used to determine readability and visual distinguishability. WCAG defines minimum contrast ratios (4.5:1 for normal text, 3:1 for large text at AA level) based on relative luminance calculations…

Colour Palette Generation(also: Color Palette Generation, Accessible Palette Generation)

The automated or semi-automated creation of sets of colours that are distinguishable by people with different types of colour vision deficiency while meeting aesthetic and functional design requirements. Despite its importance, colour palette generation is an underrepresented…

Colour Vision Deficiency(also: CVD, Color Blindness, Colour Blindness)

A condition in which a person has difficulty distinguishing between certain colours due to differences in the cone cells of the retina. CVD affects approximately 1 in 12 men and 1 in 200 women worldwide. It is not typically a complete inability to see colour but rather a reduced…

Colour blindness(also: Color blindness, Colour vision deficiency, CVD)

A condition affecting the perception of colour, caused by absent or altered photoreceptors in the retina. The main types are classified by which colour receptors are affected: protanopia (absent red receptors), deuteranopia (absent green receptors), and tritanopia (absent blue…

Colour contrast ratio(also: Contrast ratio, Luminance contrast ratio, Color contrast)

A numerical measure of the perceived brightness difference between a foreground colour (typically text) and its background, expressed as a ratio ranging from 1:1 (no contrast, identical colours) to 21:1 (maximum contrast, black on white). WCAG defines minimum contrast ratios to…

Coloured Overlay(also: Colored Overlay, Tinted Overlay, Reading Overlay)

A transparent coloured sheet placed over text or a digital colour filter applied to a screen to reduce visual stress and improve reading comfort for some people with dyslexia, Meares-Irlen syndrome, or other visual processing difficulties. Coloured overlays work by altering the…

Colours of Confusion(also: Confusion Colors, Confusable Colours, Metameric Pairs)

Pairs or sets of colours that appear distinct to people with typical colour vision but appear identical or nearly identical to people with a specific type of colour vision deficiency. These colour pairs are predicted by CVD colour models and underlie CVD simulation tools.…

Combination Repertoire

A type of technology repertoire where multiple tools work together simultaneously to provide access for a single task. For example, a person who is deaf and hard of hearing might use automatic captions, Bluetooth hearing aids, and good lighting together during in-person…

Comic Strip Conversations(also: CSC)

A visual-support technique developed by Carol Gray (1994) for autistic children and adolescents, in which a social interaction is illustrated as a short comic strip with simple stick figures, speech bubbles, thought bubbles, and colour codes for emotion. By externalising who…

Command Recognition(also: Command Classification, Input Recognition)

The process by which a computer system interprets and classifies a user's input action — such as a gesture, voice command, or key press — as a specific intended command from a predefined vocabulary of possible commands. The accuracy of command recognition is characterised by the…

Command-Line Interface(also: CLI, Command-Driven Interface, Command Interface)

A user interface style in which the user types textual commands, usually following a defined syntax, to drive a system. Command-line interfaces are typically fast and powerful for expert users, scriptable, and efficient for repetitive work, but require users to memorise commands…

Common Ground(also: Shared Understanding, Mutual Knowledge)

The mutual knowledge, beliefs, and assumptions shared between people communicating or collaborating. In accessibility and inclusive design, establishing common ground is essential for effective collaboration between people with different sensory abilities. Sighted people often…

Common Ground(also: Grounding, Mutual Understanding)

The shared knowledge, beliefs, and assumptions that conversation participants use to understand each other. In communication theory, grounding is the process by which speakers establish and maintain this mutual understanding through strategies such as referencing shared context,…

Communicability

A quality property of interactive systems proposed by Semiotic Engineering theory, referring to the system's ability to effectively and efficiently convey to users the designer's communicative intentions, logic, and underlying interaction principles. High communicability means…

Communication Access

The right and ability of all people to communicate and be understood, regardless of the mode or method of communication they use. Communication access encompasses the provision of supports, technologies, and environments that enable effective communication for people with…

Communication Access Realtime Translation(also: CART, Realtime Captioning, Stenographic Captioning)

A captioning service where a trained professional uses a stenographic keyboard to transcribe spoken language into text in real time, producing near-verbatim captions. CART provides the highest accuracy among live captioning methods and includes speaker identification, tone of…

Communication Asymmetry(also: Interaction Asymmetry, Communication Imbalance)

The imbalance in communication capabilities, speed, or modalities between conversation partners. In AAC contexts, communication asymmetry arises because AAC users communicate at 12-18 words per minute compared to 125-185 for typical speakers, creating fundamental differences in…

Communication Board(also: AAC Board, Symbol Board, Choice Board)

A low-tech or digital display of symbols, pictures, words, or phrases arranged on a surface that a person with complex communication needs can point to, touch, or select to express messages. Communication boards can be static (fixed vocabulary on a single page) or dynamic…

Communication Breakdown(also: Conversational Breakdown, Communication Failure)

A disruption in conversation where the intended message is not successfully conveyed or understood, leading to confusion, misunderstanding, or loss of conversational coherence. In AAC communication, breakdowns can occur when backchanneling cues are missed (because the partner is…

Communication Burden(also: Burden of Communication, Conversational Burden)

The disproportionate effort that people with communication-related disabilities must exert to participate in conversations, particularly in mixed-ability groups. In the context of Deaf and Hard of Hearing (DHH) individuals, communication burden refers to the repeated need to ask…

Communication Diary(also: Communication Notebook, Communication Book)

A low-tech, typically paper-based personal resource used by individuals with communication difficulties to support daily interactions. Communication diaries may contain written keywords, names, drawings, photographs, collaged objects, and other materials that serve as memory…

Communication Disability(also: Communication Impairment, Complex Communication Needs)

A condition that significantly limits a person's ability to communicate through speech, language, or other conventional means. Communication disabilities can result from neurological conditions (cerebral palsy, stroke, ALS, Parkinson's disease), developmental conditions,…

Communication Impairment(also: CI, Communication Disorder, Communication Disability)

Damage to brain functions responsible for language and memory that impairs the expression and understanding of spoken and written language. Communication impairments can result from neurological disease, stroke, or acquired brain injury, and include conditions such as aphasia…

Communication Partner(also: Conversational Partner, Interaction Partner)

A person who regularly interacts with an AAC user and supports their communication, including family members, caregivers, teachers, therapists, and peers. Communication partners play a critical role in AAC success — they model AAC use, create opportunities for communication,…

Communication Partner(also: CP, Conversation Partner)

A person who communicates with an AAC user, whether through speech, sign, or other means. Communication partners play a critical role in the success of AAC interactions — their willingness to wait, their ability to interpret messages, and their understanding of AAC devices…

Communication Partner Training(also: Conversation Partner Training)

Structured training for the people who regularly communicate with an AAC user — including family members, caregivers, teachers, and peers — to help them support effective communication. Communication partner training teaches strategies such as allowing extra time for AAC…

Communication Privacy Management Theory(also: CPM, CPM Theory)

A communication theory developed by Sandra Petronio that treats private information as something people own and collectively manage through negotiated rules about boundaries, co-ownership, and turbulence (boundary violations). CPM is widely used to analyse online…

Communication Rate(also: Communication Speed)

The speed at which a person can convey messages, typically measured in words per minute (WPM). For AAC users, communication rate is often significantly slower than natural speech (100-200 WPM)—unaided AAC users may achieve only 2-10 WPM with scanning systems, while more advanced…

Communicational Accessibility(also: Communicative Accessibility)

An approach to accessible design that goes beyond providing access to raw content (content accessibility) to preserving the designer's intended communicative strategy across all modalities and for all users. Where content accessibility asks "can the user access the…

Communitas

A sense of community, solidarity, and mutual support that emerges among people sharing a liminal or transitional experience. Coined by anthropologist Victor Turner, communitas describes the bonds formed when individuals navigate uncertain life transitions together. In…

Communities of Practice(also: CoP)

Groups of people who share a concern or passion for something they do and learn how to do it better through regular interaction. In accessibility, communities of practice form around shared experiences of navigating barriers, developing workarounds, creating accessible tools,…

Community Advocate(also: Peer Advocate, AT Champion)

An individual, often a person with a disability or caregiver, who voluntarily promotes awareness of assistive technology programs and resources within their community. Community advocates play a crucial role in expanding the reach of AT services by sharing information through…

Community Based Participatory Research(also: CBPR, Participatory Action Research)

A research methodology that creates equitable partnerships between researchers and community members throughout the entire research process, from defining research questions to disseminating findings. CBPR aims to reduce health and social disparities by ensuring that the people…

Community Care(also: Community-Based Care, Care in the Community)

A policy and practice model in which health and social care services are provided to disabled and elderly people in their own homes or local communities rather than in residential institutions. Community care aims to promote independence, choice, and social inclusion, but can…

Community Center(also: Community Space, Community Hub)

A physical or virtual space where members of a particular community gather for social support, resources, education, and shared activities. In the context of marginalized communities such as LGBTQIA+ individuals and people with disabilities, community centers serve as safe…

Community Health Worker(also: CHW, Lay Health Worker)

A frontline healthcare provider who is a trusted member of the community they serve and who delivers basic health services, education, and referrals, typically with limited formal training. Community health workers extend the reach of formal health systems into homes and…

Community Navigation(also: Community Travel, Community Mobility)

The ability to plan, initiate, and complete trips within one's community, including getting to transit points on time, using public transportation, and accessing services at destinations. For people with cognitive disabilities such as traumatic brain injury, community navigation…

Community Sourcing(also: Community-Driven Accessibility)

An approach to creating accessible content by drawing on community members who have domain expertise or vested interest in the content, rather than relying on professional describers or general crowdworkers. Unlike crowdsourcing, which draws from a broad pool of workers who may…

Community Sustainability(also: Research Sustainability)

The principle that research practices should not deplete, harm, or overburden the communities from which participants are recruited. In accessibility research, community sustainability requires considering the cumulative impact of multiple studies drawing from the same…