Glossary

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Mixed-Visual Group(also: Mixed visual ability group, Mixed-visual ability group)

A group whose members include both blind or low-vision and sighted participants. The term is used in accessibility research on group activities (museum tours, classrooms, family outings, workplace meetings) to focus on the specific accessibility challenges that arise when blind…

Modality(also: Interaction Modality, Interface Modality)

The sensory channel or communication method through which a user interacts with a computer system, such as visual (graphical displays), auditory (speech or non-speech audio), tactile (braille, haptic feedback), or textual (command-line) output, and keyboard, mouse, voice,…

Mood(also: Affect, Affective State)

In affective computing and music research, the emotional quality a stimulus evokes in a listener or viewer, commonly characterized along dimensions such as valence (pleasant–unpleasant) and arousal (calm–energetic). Mood is a core target for music information retrieval systems…

Mutual Support(also: Mutual support in HRI, Mutual assistance)

In accessibility and human-robot interaction research, a framing that moves beyond one-way robot-supports-user or user-supervises-robot models toward a bidirectional relationship in which each party compensates for the other's limitations. For a blind user travelling with an…

Navigation Order(also: Focus Order, Tab Order, Reading Order)

The sequence in which a user encounters interface elements when navigating with assistive technology, a keyboard, or other non-visual means. A logical navigation order follows the visual layout and semantic structure of the page, typically moving left-to-right and top-to-bottom…

Nonvisual Accessibility(also: Non-Visual Access)

Nonvisual accessibility refers to approaches, strategies, and technologies that enable people who are blind or have low vision to access information and interact with digital and physical environments without relying on sight. This encompasses screen readers, braille displays,…

Normate

A term coined by disability studies scholar Rosemarie Garland-Thomson to name the cultural figure - the imagined 'normal' body - against which other bodies are measured, valued, and judged deficient. The normate is not a real person but a template produced through social…

Opportunistic Accessibility(also: Opportunistic Accessibility Improvement)

Opportunistic accessibility is an approach to improving digital accessibility in which enhancements are automatically applied to the maximum extent possible without causing negative side effects. Rather than treating accessibility as an all-or-nothing goal, opportunistic…

PVI(also: People with Visual Impairments, Person with Visual Impairment, Persons with Visual Impairments)

An abbreviation widely used in HCI and accessibility research for "people with visual impairments," a person-first umbrella term that includes people who are blind, legally blind, or have low vision. PVI is often used interchangeably with BVI ("blind and visually impaired") and…

Passive Haptic Feedback(also: Passive tactile feedback)

Tactile information provided to a user by the inherent physical properties of a device or interface, without any active actuation. Examples include the raised bezel around a touch screen, the tactile bump on the F and J keys of a keyboard, a notched dial, or the edge of a…

Perceptual Gap

A design failure identified by Choudhury (2026) in which an AI system's explanation is delivered through exactly the sensory channel that its user cannot access. For example, a Grad-CAM heat map overlaid on an image tells a blind user where the model looked but cannot be seen by…

Personalized Dynamic Accessibility(also: Dynamic Accessibility, Adaptive Accessibility)

An approach to accessibility where systems automatically detect user abilities and adapt interface settings in real-time to match current needs. Unlike static accessibility settings that remain constant, personalized dynamic accessibility recognizes that an individual's…

Pervasive Accessible Technology(also: PAT)

A strategy for integrating accessibility directly into information technology infrastructure rather than retrofitting it after the fact. Proposed by Michael Paciello in 1996, Pervasive Accessible Technology combines a Standard Human Interface with an Accessible Information…

Pitch

The perceived highness or lowness of a sound, determined primarily by its fundamental frequency (measured in Hertz). Pitch is one of the primary dimensions along which music and speech are organized, underpinning melody, harmony, and prosody. In accessibility work, pitch is…

Presentation Independence(also: Presentation-Independent Information)

The principle that information should be stored and served in formats that can be rendered in visual, auditory, or electronic text form without loss of meaning. Presentation-independent content has no inherent visual or auditory presentation and can be adapted to the needs of…

Print Disabilities(also: Print Disability, Print Impairment)

A broad term encompassing any condition that prevents a person from effectively reading standard printed text. Print disabilities include blindness and low vision, but also extend to learning disabilities such as dyslexia, physical disabilities that prevent holding or…

Privacy

The right and practical ability of a person to control the collection, use, and disclosure of information about themselves, their body, their activities, and their relationships. For accessibility, privacy intersects with disability in specific ways: assistive-technology usage…

Progressive Enhancement

A web design strategy that starts with a baseline of essential content and functionality that works in any browser or with any internet connection, then layers on enhanced features for users with more capable browsers or greater bandwidth. Rooted in the "graceful transformation"…

Recreational Exploration(also: Wandering exploration, Exploratory navigation, Open-ended exploration)

Movement through an environment driven by interest, curiosity, or enjoyment rather than by a fixed destination — for example wandering a museum, browsing a shopping mall, or exploring a neighbourhood. For blind and low-vision people, recreational exploration is harder to support…

Redundant Input(also: Redundant Input Channels, Multimodal Redundancy)

A design approach in which a user interface accepts the same command through more than one input channel — for example, voice and gesture, keyboard and pointer, or speech and switch — so that users can choose whichever modality suits their current abilities, context, or…

Semantic Abstraction

The practice of defining interface elements, content, or interactions by their meaning and purpose rather than their specific visual or physical presentation. In accessibility, semantic abstraction is a foundational principle — semantic HTML elements like nav, main, and button…

Signifier(also: Perceived Affordance)

A perceptible cue — visual, auditory, or tactile — that indicates how an element can or should be used, making an underlying affordance discoverable. In Don Norman’s refinement of affordance theory, the affordance is the action possibility, and the signifier is the signal that…

Simultaneous Assistance

Simultaneous assistance, described by Cynthia Bennett and Daniela Rosner, is a form of support in which help flows in multiple directions at once rather than unidirectionally from a non-disabled helper to a disabled recipient. In a simultaneous-assistance encounter, the disabled…

Situational Limitations(also: Situational Impairments, Contextual Limitations)

Temporary constraints on a user's ability to interact with technology due to their environment, device, or circumstances rather than a permanent disability. Examples include using a mobile phone in bright sunlight (limiting screen visibility), being in a noisy environment…

Situational Visual Impairment(also: SVI, Situational Visual Impairments)

A temporary reduction in a person's effective vision or reading performance caused by the environment or context rather than by a medical condition. Common examples include trying to read a phone screen in bright sunlight, while walking or on a moving vehicle, in low light, or…

Situationally-Induced Impairments and Disabilities(also: SIIDs, Situationally Induced Impairments and Disabilities, Situation-Induced Disabilities)

An accessibility framework, introduced by Sears et al., that describes how everyday environments and tasks can temporarily impose the same kinds of barriers on non-disabled users that permanent impairments create for disabled users. Examples include reading a phone in bright sun…

Social Play

Social play is intrinsically motivated, voluntary activity between two or more children that has no purpose beyond itself, yet is essential to emotional, cognitive, and social development. Developmental researchers categorise it along two axes: social level (Parten's six stages…

Speech Dialogue Design(also: Speech Interface Design, Auditory Dialogue Design)

The practice of designing the structure, content, ordering, and delivery of information presented through synthetic speech in computer interfaces. Effective speech dialogue design considers psycholinguistic principles such as the recency effect (items heard last are best…

Speech Diversity(also: Diverse Speech, Non-Typical Speech)

The full range of ways human speech varies from the narrow 'typical' speech on which most speech-AI systems are trained and benchmarked. Speech diversity includes people who stutter, d/Deaf and Hard-of-Hearing speakers, people with dysarthria, aphasia, or other neurological…

Standard Human Interface(also: SHI)

A concept within the Pervasive Accessible Technology framework referring to a standardized set of input and output capabilities — including microphones, speakers, touch screens, glidepoint touchpads, kiosks, infrared devices, and video cameras — that serve as the physical point…

Symbiotic Learning

Symbiotic Learning is a conceptual framing introduced by Jiang et al. (CHI 2026) describing a mode of mixed-ability family learning in which parents and children mutually enable each other's participation and development through AI-mediated communication. Rather than positioning…

System-Class Accessibility(also: Platform-Level Accessibility)

The architectural support built into an operating system to make the entire platform usable by people with disabilities. System-class accessibility encompasses three components: alternative input and output modalities (such as speech synthesis, braille displays, and switch…

Technical Agency

Technical agency, in the context of augmentative and alternative communication (AAC), refers to an individual's ability to actively participate in and contribute to a conversation through direct actions such as speaking, gesturing, or vocalizing. It is distinguished from…

Tempo(also: BPM, Beats Per Minute)

The speed or pace of a musical piece, typically measured in beats per minute (BPM). Tempo is one of the primary features that shapes emotional perception of music — fast tempos (130+ BPM) are associated with excitement and urgency, slow tempos (60–80 BPM) with calm or solemnity.…

Transformative Access

A concept from disability justice that redefines accessibility beyond structural adjustments or compliance with standards. Introduced by the disability justice group Sins Invalid, transformative access advocates not only for removing barriers but for shifting societal norms to…

Tree Navigation(also: Hierarchical Navigation, Tree View Navigation)

The process of moving through and exploring hierarchical data structures (trees) such as file systems, program structures, organizational charts, or menu systems. In accessible computing, tree navigation is a significant challenge because screen readers typically present tree…

Turing Test(also: Imitation Game)

The Turing Test, proposed by Alan Turing in 1950, is a thought experiment for assessing whether a machine's conversational behaviour is indistinguishable from that of a human. A human evaluator engages in a text-based exchange with both a human and a machine and must decide…

UI Semantics(also: User Interface Semantics, Interface Semantics)

The meaningful properties and roles of user interface elements that go beyond their visual appearance, including what an element does, how it can be interacted with, and its relationship to other elements. UI semantics are essential for accessibility because assistive…

Universal Access Reference Model(also: UARM)

A conceptual framework for understanding and addressing the full range of user needs in information and communication technology. The Universal Access Reference Model provides a structured approach to identifying and removing barriers to accessibility by modelling the…

Universal Design(also: UD, Design for All, Inclusive Design)

Universal Design is the design philosophy and practice of creating products, environments, and systems that are usable by all people, to the greatest extent possible, without the need for adaptation or specialized design. Originating in architecture through the work of Ronald…

Upper Ontology(also: Foundation Ontology, Top-level Ontology)

An upper ontology is a high-level, domain-independent ontology that describes very general concepts — such as 'object', 'role', 'event', 'time', or, in a web-accessibility context, generic structural roles like 'menu', 'navigation', 'content region', or 'decoration'. It is…

User Interface Management System(also: UIMS)

A software framework that separates user interface presentation and interaction from application logic, allowing the interface to be designed, modified, or replaced independently of the underlying program. A UIMS typically manages input handling, output rendering, and the…

User-System Model(also: User-System Interaction Model)

A conceptual model that describes the relationship between a user and the technology system they interact with, taking into account the user's abilities, preferences, and needs alongside the system's capabilities, interfaces, and constraints. In accessibility engineering,…

View Hierarchy(also: UI Hierarchy, Accessibility Hierarchy, DOM Tree)

The tree-structured representation of how user interface elements are organized and nested within an application. The view hierarchy defines parent-child relationships between UI components, specifying which elements are contained within others and how they are grouped. This…

Visual Affordance(also: Visual Affordances)

A visually conveyed cue that signals how an object can be used or what it represents - for example, a handle suggesting 'grasp', a button suggesting 'press', or color and labeling suggesting product identity. Many visual affordances are inaccessible through touch alone: blind…

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…

Visually Impaired(also: Vision Impairment, Visual Impairment, BVI)

An umbrella term for any degree of reduced visual function that cannot be fully corrected with standard glasses or contact lenses, ranging from mild low vision to total blindness. The term is frequently combined as BVI (blind and visually impaired) in accessibility research to…

Web Accessibility Barrier(also: WAB, Accessibility Barrier)

Any element, design pattern, or technical implementation on a web page that prevents or hinders people with disabilities from accessing, understanding, or interacting with content. Common web accessibility barriers include images without alternative text, videos without…

Web Mobility(also: Hypertext Mobility, Web Navigation Mobility)

A conceptual framework that applies principles of physical mobility and wayfinding to web navigation, particularly for visually impaired users. Web mobility encompasses the ability to move through hypertext with purpose, ease, and accuracy, requiring knowledge of current…

Window Shopping(also: Recreational window-shopping, Browsing)

The casual practice of looking at shops, displays, or goods without a specific purchase in mind — social activity valued for its own sake as much as for any eventual transaction. Accessibility research frames window-shopping as a form of non-instrumental exploration that is…