Glossary

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Red-teaming(also: Red team testing)

A structured adversarial-testing practice in which a dedicated team deliberately attempts to break, manipulate, or provoke harmful outputs from a system — originally from military strategy, now widely used for AI systems including large language models. In an accessibility and…

Redundancy Principle

A principle from the Cognitive Theory of Multimedia Learning stating that people learn better from graphics and narration than from graphics, narration, and on-screen text presenting the same words, because presenting identical information in both spoken and written form…

Redundant Encoding(also: Redundant Coding, Multi-Channel Encoding)

A design principle that communicates information through multiple visual channels simultaneously — such as colour plus shape, pattern, text label, or position — so that no single channel is required for comprehension. Redundant encoding is a foundational recommendation for CVD…

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…

Reference Sonification(also: Audio reference tone, Origin tone)

A sonification design pattern in which a fixed, recognisable audio tone represents a known landmark - typically the origin of a coordinate system or another anchor point - and can be re-played on demand so that a user exploring a non-visual data space can re-orient themselves…

Referential Drift

Referential drift is a failure mode in AI-generated sign language where spatial loci — the established positions in signing space used to refer to people, objects, or locations — shift or are not maintained consistently across a sentence. Because signed languages use spatial…

Reflection-in-Action(also: Reflection-on-Action)

A concept from Donald Schön's theory of reflective practice (The Reflective Practitioner, 1983) describing how skilled practitioners adjust their approach in the moment, based on tacit knowledge and immediate feedback from the situation, rather than by following pre-specified…

Reflexive Ethnography

Reflexive ethnography is an approach to ethnographic research in which the researcher explicitly documents and analyses how their own identity, assumptions, relationships and shifting position in the field shape the knowledge produced. Rather than presenting findings as neutral…

Reflexive Thematic Analysis(also: RTA)

A qualitative data analysis method developed by Braun and Clarke that involves open-coding transcripts, identifying patterns, and organizing findings into themes through iterative refinement. Reflexive thematic analysis emphasizes the researchers's positionality and how their…

Reflexive thematic analysis(also: RTA)

A qualitative research method developed by Braun and Clarke that involves the researcher actively and reflexively generating themes from data, rather than treating themes as pre-existing entities to be discovered. Unlike other thematic analysis approaches, RTA explicitly…

Reflexivity(also: Researcher Reflexivity)

A research practice in which scholars continuously examine how their own identities, positions, assumptions, disciplinary training, and power relationships shape the research they conduct — the questions they ask, the methods they choose, the participants they recruit, and the…

Refractive Error(also: Refractive Disorder, Ametropia)

Refractive error is a common vision condition in which the shape of the eye prevents light from focusing correctly on the retina, resulting in blurred vision. Types include myopia (nearsightedness), hyperopia (farsightedness), astigmatism (irregular corneal curvature), and…

Refreshable Braille Display(also: Braille Display, Braille Terminal, Refreshable Tactile Display)

An electromechanical device that renders Braille characters by raising and lowering small pins through a flat surface, allowing blind users to read digital text output by touch. These devices connect to computers or mobile devices and work alongside screen readers to provide…

Refreshable Braille Display(also: Refreshable Braille, Dynamic Braille Display, Electronic Braille Display)

An electromechanical device that renders Braille characters by raising and lowering pins dynamically, allowing blind users to read digital text through touch. Conventional refreshable Braille displays present a single line of text (typically 20-80 characters) using piezoelectric…

Refreshable Graphics Display(also: Tactile Graphics Display, Dynamic Tactile Display)

A device that presents tactile graphics and diagrams through an array of pins that can be individually raised or lowered to create dynamic, changeable tactile patterns. Unlike static tactile graphics (embossed paper or thermoform), refreshable displays can show sequences of…

Refreshable Tactile Display(also: RTD, Refreshable Braille Display, Dynamic Tactile Display)

An electronic device that presents tactile graphics and content through an array of small pins that can be independently raised or lowered to create dynamic, changeable tactile surfaces. Unlike traditional static tactile graphics produced on paper through embossing or…

Region of Interest(also: ROI, Area of Interest, AOI)

A specific area within an image, video frame, or user interface that has been identified as particularly relevant or important for analysis or user attention. In eye-tracking research, regions of interest are predefined areas on a stimulus where fixation data is collected to…

Regional Sign Variation(also: Sign Language Dialect, Regional Sign Dialect)

Regional sign variation refers to systematic differences in the form of signs across geographic regions within a single sign language, analogous to dialects in spoken languages. Variation arises from local Deaf school traditions, contact between communities, and historical…

Regression(also: Regressive Saccade, Regressive Eye Movement)

In the context of reading and eye tracking, a regression is a backward eye movement (right-to-left in left-to-right scripts) where the reader returns to previously read text. Regressions typically occur when a reader has difficulty understanding a word or passage and needs to…

Rehabilitation(also: Rehab, Therapeutic Rehabilitation)

A set of interventions designed to restore or optimize functioning and reduce disability in individuals with health conditions. Rehabilitation may address physical, cognitive, sensory, or communication abilities through exercises, therapies, assistive devices, and environmental…

Rehabilitation Engineering(also: Rehab Engineering)

An engineering discipline focused on quantifying, measuring, and modeling human performance to provide better-fitting assistive technology adaptations. Rehabilitation engineering emerged partly as a response to trial-and-error approaches in assistive technology, bringing…

Rehabilitation Gaming(also: Rehab Gaming, Therapeutic Gaming)

The use of digital games that incorporate physical rehabilitation exercises into gameplay, transforming repetitive therapeutic movements into engaging interactive experiences. Rehabilitation games map exercises such as cycling, reaching, balancing, or arm movements to in-game…

Rehabilitation science(also: Rehabilitation research)

An interdisciplinary field focused on understanding and improving function, independence, and quality of life for people with disabilities, injuries, or chronic conditions. Rehabilitation science draws on medicine, engineering, psychology, and social science to develop…

Reification

The process of making concrete that which is abstract. A photograph is a reification of a moment in time and place, with all the selectivity and distortion that the lens and framing impose. A web page is a reification of underlying data and semantic relationships, rendered…

Reinforcement Learning(also: RL)

A type of machine learning where a system learns to make decisions by performing actions in an environment and receiving rewards or penalties based on the outcomes. Unlike supervised learning, which learns from labelled examples, reinforcement learning discovers optimal…

Reinforcement Learning from Human Feedback(also: RLHF)

A machine learning technique used to fine-tune large language models by incorporating human judgments about response quality. Human annotators rank or rate model outputs, and this feedback trains a reward model that guides the LLM toward producing preferred responses. While RLHF…

Rejection Sensitivity(also: Rejection Sensitive Dysphoria, RSD)

An intense emotional response to perceived or actual rejection, criticism, or failure that is commonly experienced by neurodivergent individuals, particularly those with ADHD and autism. Rejection sensitivity can significantly impact job-seeking behaviour, as the fear of…

Rejection Sensitivity Dysphoria(also: RSD)

An intense, disproportionate emotional response to perceived or actual rejection, criticism, or failure, commonly reported by people with ADHD and often linked to trauma from chronic social rejection and the ongoing stigma of neurodivergence. RSD is not a formal diagnostic…

Relational Accessibility(also: Relational Access)

An approach to accessibility that treats access as something co-constructed between people in everyday life, rather than a property of an individual user, tool, or environment. Relational accessibility recognises that communication, care, and adaptation are ongoing practices…

Relational Diagram(also: Relational Information Display, RID)

A graphical representation that depicts items (nodes) and the relationships (links) between them using a two-dimensional spatial layout. Common forms include entity-relationship diagrams, flowcharts, state diagrams, network diagrams, and mind maps. Relational diagrams encode…

Relational Sovereignty

A framework proposed by Jang, Carrington and Begel (2026) as a new goal (telos) for socially assistive technology, defined as the recognised authority of a disabled person to choose their relational mode — acting independently or interdependently — and to set the terms on which…

Relative Font Sizing(also: Relative Units, Scalable Typography, Flexible Font Sizes)

The practice of specifying text sizes using relative units (such as em, rem, or percentages) rather than absolute units (such as pixels or points), allowing text to scale when users adjust their browser or system font size settings. Relative font sizing is an important…

Relative Virtuosity

A concept from performance studies arguing that what constitutes a virtuoso performance cannot be separated from the social and material expectations around non-normative bodies. For disabled performers, virtuosity is shaped by how their bodies interact with the world, their…

Relaxed Scoping(also: Flexible Scoping)

A voice navigation strategy that allows users to name any target on the screen directly without first navigating through a hierarchy. Relaxed scoping prioritizes efficiency by enabling single-command access to interface elements, but it increases the potential for target…

Relevance Scoring(also: Task Relevance Score, Content Relevance Rating)

The assignment of numerical scores to web page elements indicating how relevant they are to a user's specified task or goal. In systems like Task Mode, relevance scores typically range from 0 (completely irrelevant) to 100 (critical to the task), assigned by large language…

Relevance Threshold(also: Filtering Threshold, Display Threshold)

A user-adjustable cutoff value that determines which content elements are displayed or hidden based on their relevance scores. Elements scoring above the threshold are shown; those below are de-emphasized or removed. Relevance thresholds provide users with agency over how…

Relief Chart(also: 3D Chart, Haptic Chart, Relief Graph)

A tactile data visualization that uses height (the third dimension) to encode data values, making charts accessible to people with visual impairments through touch. Unlike flat tactile graphics that use only texture or raised lines, relief charts represent data magnitude through…

Remediation(also: Accessibility Remediation, Barrier Remediation)

The process of identifying and fixing accessibility barriers in existing digital content, tools, or platforms after they have been created or deployed. Remediation is typically a reactive approach to accessibility, addressing problems found through audits or user complaints.…

Reminder System(also: Prompting System, Cognitive Prosthetic)

An assistive technology that provides timely cues, alerts, or step-by-step prompts to support task completion for people with memory or executive function difficulties. Reminder systems can range from simple timer-based alerts to sophisticated context-aware systems that track…

Reminiscence(also: Reminiscing, Life Review)

The process of recalling and sharing past experiences, often prompted by sensory cues like photographs, music, or familiar objects. For people with dementia, reminiscence can be more accessible than discussing current events because long-term memories are often better preserved…

Reminiscence(also: Reminiscence Therapy)

The process of recalling and reflecting on past personal experiences, often used therapeutically to promote mental well-being in older adults. Reminiscence therapy involves structured activities that trigger memories through sensory cues, familiar locations, music, or…

Reminiscence Therapy(also: Reminiscence-Based Therapy, Life Review Therapy)

A non-pharmacological therapeutic approach for people with dementia that uses artifacts, photographs, music, and other personally meaningful materials to stimulate recall of past experiences and prompt conversation about life events. Reminiscence therapy aims to maintain the…

Reminiscence therapy(also: Reminiscence, Life review therapy, Memory sharing)

A therapeutic intervention widely used with older adults and people with dementia that involves the structured recall and sharing of personal memories and life experiences, often supported by prompts such as photographs, music, objects, or — increasingly — digital technologies.…

Remnant book(also: remnant scrapbook, memory book)

An AAC strategy that uses collected physical artifacts—such as ticket stubs, photos, business cards, and other tangible items—organized in a book or album to support communication for people with aphasia or other cognitive-communication disorders. Remnant books leverage…

Remote Accessibility Assessment(also: Virtual Accessibility Assessment, Pre-Visit Accessibility Check)

The practice of evaluating the physical accessibility of an unfamiliar environment without being physically present. Wheelchair users and others with mobility disabilities routinely assess spaces in advance to avoid dangerous, inaccessible, or frustrating situations. Current…

Remote Assistance(also: Remote Sighted Assistance, Visual Interpreting)

A service model where people who are blind or have low vision connect with sighted volunteers or trained agents via a live video call to receive real-time visual descriptions and guidance. Services like Be My Eyes and Aira use smartphone cameras to share the user's environment…

Remote Captioning(also: Remote CART, Remote Real-Time Captioning)

A live captioning service delivered at a distance, in which a human captioner (CART provider) or automatic speech recognition system receives an audio feed from a meeting, classroom, or event over the internet or a phone line and transmits transcribed text back to the user in…

Remote Classroom(also: Virtual Classroom, Distance Learning Classroom)

A learning environment in which instructors and learners are geographically separated and connected through video, screen-sharing, and communication channels that approximate in-person teaching. Effective remote classrooms for accessibility purposes typically combine a main…

Remote Desktop Software(also: Remote Access Software, Remote Control Software)

Software that allows a user to access and control one computer from another device over a network, displaying the remote computer's screen and relaying input commands. In accessibility contexts, remote desktop software serves as an unexpected but powerful assistive technology…

Remote Interpretation(also: Remote Sign Language Interpreting, Distance Interpreting)

The provision of sign language or spoken language interpretation services through technology platforms that use live video streaming, allowing the interpreter to work from a different location than the participants. Remote interpretation encompasses both video remote…