Glossary

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Trace R&D Center(also: Trace Center, Trace Research and Development Center)

A pioneering research center focused on accessibility and assistive technology, originally established at the University of Wisconsin-Madison in 1971 and later affiliated with the University of Maryland. Founded and long directed by Gregg Vanderheiden, the Trace Center developed…

Tracheoesophageal puncture(also: TEP, tracheoesophageal voice prosthesis, TE puncture)

A surgical procedure that creates a small opening (fistula) between the trachea and esophagus to restore voice production after total laryngectomy. A one-way valve is inserted that allows exhaled air to pass into the esophagus, where vibrations in the pharyngoesophageal segment…

Tracheostomy(also: Tracheotomy)

A surgical procedure that creates an opening (stoma) in the front of the neck into the trachea (windpipe), through which a tube is inserted to provide an airway for breathing. Like intubation, a tracheostomy typically prevents or significantly impairs speech because air no…

Trackball

A trackball is a pointing device consisting of a ball housed in a stationary socket that the user rotates to move the on-screen cursor, with buttons nearby for clicking. Unlike a mouse, a trackball does not require arm movement across a surface, making it valuable for people…

Tracked Captions(also: Speaker-following captions, Dynamic captions)

Captions that move dynamically within the video frame to stay near the current speaker's face or mouth, rather than remaining anchored at a fixed position (typically the bottom of the video). Tracked captions reduce the visual effort required for Deaf and Hard-of-Hearing viewers…

Training Data(also: Training Set, Training Dataset)

The collection of labeled examples used to teach a machine learning model to perform a specific task. The quality, quantity, and diversity of training data directly determine how well a model will perform. In accessibility contexts, training data quality is especially important…

Training Wheels Interface(also: Training Wheels, Progressive Disclosure)

An interface design pattern that reduces complexity for novice users by hiding or disabling advanced features until they are needed, then gradually revealing them as the user gains competence. Named after the stabilizing wheels on children's bicycles, this approach prevents…

Trajectory Analysis(also: Route Analysis, Path Analysis)

The computational study of movement patterns over time and space, typically derived from GPS or other location data. Trajectory analysis involves modelling, comparing, and classifying sequences of spatial positions to identify patterns, anomalies, or behaviours. In assistive…

Trajectory Playback(also: Haptic Playback, Force-Guided Movement)

A technique in haptic interfaces where a force-feedback device physically guides a user's hand through a predefined path or shape. The system applies forces to move the user along a trajectory, allowing them to perceive spatial information through proprioception and kinesthetic…

Transactional Communication Model

The most dynamic model of communication, in which all parties are simultaneously senders and receivers, co-creating meaning through instantaneous, continuous feedback. In this model, communication is a collaborative process where context, environment, and shared understanding…

Transcoding(also: Content transcoding, Web transcoding)

The process of converting or transforming web content from one format or structural representation to another to improve accessibility. In the context of screen reader access, transcoding can involve detecting visual layout semantics like grid structures and converting them into…

Transcript(also: Text Transcript, Video Transcript, Audio Transcript)

A written document containing the complete text of spoken content from a video or audio recording, presented separately from the media rather than synchronized with it. Unlike captions, which appear on-screen in real time as speech occurs, transcripts provide all text at once,…

Transcription(also: Speech-to-Text Transcription, Real-Time Transcription)

The process of converting spoken language into written text, either in real time or after the fact. In accessibility contexts, transcription services provide communication access for deaf and hard of hearing individuals by producing text versions of spoken content in classrooms,…

Transcripts(also: Transcript, Text Transcript)

A written, text-based representation of spoken audio or audiovisual content. WCAG 2.1 success criterion 1.2.1 (Audio-only and Video-only Prerecorded) requires an alternative for time-based media — typically a transcript — for pre-recorded audio-only content such as podcasts,…

Transfer Function(also: Mapping Function, Control-Display Gain)

A mathematical function that defines the relationship between an input signal and an output response in a control system. In assistive technology and pointer control, a transfer function determines how physical movements (such as head movements, eye gaze, or joystick input) are…

Transfer Learning

A machine learning technique where a model trained on a large general dataset is adapted to perform a new, more specific task using a much smaller amount of new training data. Rather than training a model from scratch, transfer learning leverages patterns already learned by an…

Transfer Machine Translation(also: Transfer MT, Rule-Based Transfer Translation)

A rule-based machine-translation paradigm that analyses the source text into a syntactic or semantic structure, applies a set of transfer rules to produce a corresponding structure in the target language, and then generates the target surface form. Transfer MT sits between…

Transferable Skills(also: Portable Skills, Cross-Functional Skills)

Abilities and competencies that can be applied across different jobs, industries, and contexts rather than being specific to a single role. In vocational rehabilitation and disability employment contexts, transferable skills training focuses on capabilities like organization,…

Transformation Proxy(also: Transcoding Proxy, Web Accessibility Proxy)

A transformation proxy is an intermediary server that sits between a user and the web, intercepting web pages and modifying their content before delivering them to the user's browser. In accessibility contexts, transformation proxies are used to improve the accessibility of web…

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…

Transformer(also: Transformer Model, Transformer Architecture)

A deep learning architecture introduced by Vaswani et al. in 2017 that relies entirely on attention mechanisms rather than recurrence (RNNs) or convolution for sequence modeling tasks. Transformers process entire input sequences in parallel using "self-attention" to weigh the…

Transinstitutionalization

The transition of disabled people from one type of institutional setting to another rather than to genuine community-based living. For example, the movement of disabled individuals from clinical institutions such as psychiatric hospitals to criminal institutional settings such…

Transit Accessibility(also: Public Transit Accessibility, Transportation Accessibility)

The degree to which public transportation systems — including rail, bus, and subway networks — can be used by people with disabilities and others with mobility needs. Transit accessibility encompasses physical infrastructure (elevators, ramps, raised platforms, tactile…

Transit accessibility(also: Public transportation accessibility, Accessible transit)

The degree to which public transportation systems — including buses, trains, subways, and associated infrastructure like stops, stations, and information systems — are usable by people with disabilities. Transit accessibility encompasses vehicle design (ramps, priority seating,…

Transition Period(also: School-to-Adult Transition, Transition Services)

In disability services, the transition period refers to the years during which a young person with a disability moves from school-based supports into adult life. In the United States, school systems are legally required to provide full-time services to students with disabilities…

Transitional Object(also: Comfort Object)

A concept from developmental psychology, introduced by D. W. Winnicott, referring to a soft, often tactile object - a blanket, stuffed toy, or similar - that a child uses to support self-soothing and the transition between dependence on a caregiver and independent experience.…

Translanguaging

The practice of drawing on multiple languages within a single interaction or communication act, leveraging a person's full linguistic repertoire rather than treating languages as separate, bounded systems. Translanguaging is particularly relevant to accessibility for…

Translated Deaf Self

A concept coined by Alys Young, Jemina Napier, and Rosemary Oram describing how deaf signers' lifelong experiences of being encountered, represented, and inter-subjectively known by others occur in a translated form. The term captures the ontological consequences of routine…

Transliteration(also: Sign Language Transliteration)

The word-by-word conversion of text from one system into another — for example, rendering a name in one script using the characters of another. In sign-language accessibility the term has a specific meaning: producing a signed form of spoken or written English by substituting a…

Transparency in AI(also: AI Transparency, Algorithmic Transparency)

The principle that AI systems should clearly communicate how they work, what data they use, where processing occurs, and what their limitations are. In accessibility contexts, blind users have expressed strong desires to understand how AI-enabled privacy techniques are designed,…

Transparent Video Overlay(also: Transparent Video, Video Overlay, Translucent Video)

A display technique where a live video feed is rendered as a semi-transparent layer on top of another application, allowing users to see both the video content and the underlying application simultaneously. In accessibility contexts, transparent video overlays have been used to…

Transphobia(also: Anti-Transgender Prejudice, Anti-Trans Bias)

Transphobia refers to prejudice, discrimination, and hostility directed at people who are transgender, non-binary, or whose gender identity or expression differs from their sex assigned at birth. In digital accessibility and technology contexts, transphobia manifests through AI…

Transportation Accessibility(also: Accessible Transportation, Mobility Accessibility)

The design and provision of transportation systems, services, and infrastructure that are usable by people with disabilities. Transportation accessibility encompasses physical access to vehicles and transit stops, accessible information systems (route planning, real-time…

Trauma-Informed Care(also: TIC, Trauma-Informed Approach)

A framework originating in social work practice that asks organisations and service providers to recognise the widespread impact of trauma on the people they serve and to integrate that understanding into their policies, procedures, and interactions. Rather than directly…

Traumatic Brain Injury(also: TBI, Acquired Brain Injury, Head Injury)

An injury to the brain caused by an external bodily force, typically from road traffic accidents, falls, or other impacts. TBI severity is classified using the Glasgow Coma Scale (GCS): mild (GCS 13-15), moderate (GCS 9-12), and severe (GCS 3-8), with additional factors…

Traumatic brain injury(also: TBI, Acquired brain injury)

An injury to the brain caused by an external force such as a blow, jolt, or penetrating object, resulting in temporary or permanent impairments to cognitive, physical, and psychosocial functioning. TBI can affect attention, memory, executive function, language processing, social…

Travel Chain(also: Mobility Chain, Journey Chain)

A travel chain is the complete sequence of connected stages that make up a journey from origin to destination, including planning, leaving the starting point, walking to transport, using public transport, navigating outdoor environments, entering buildings, and finding specific…

Travel Training(also: Mobility Training, Independent Travel Training)

Structured instruction that teaches people with disabilities how to travel independently and safely using public transportation or walking routes. Travel training typically involves repeated practice of specific routes, learning to recognize landmarks, understanding timetables,…

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…

Tremor(also: Hand Tremor, Essential Tremor)

An involuntary, rhythmic shaking movement of one or more parts of the body, most commonly affecting the hands. Tremor can result from various conditions including essential tremor, Parkinson's disease, multiple sclerosis, stroke, or medication side effects, and its severity can…

Trichromat(also: Trichromacy, Trichromatic Vision)

A person with typical colour vision based on three types of functional cone cells (L, M, and S cones) in the retina, each sensitive to different wavelengths of light corresponding roughly to long (red), medium (green), and short (blue) wavelengths. Trichromatic vision allows…

Trigger Avoidance(also: Avoidance Behavior, OCD Avoidance)

A compulsive behavior pattern in OCD where individuals minimize or eliminate contact with situations, objects, people, or places that trigger their obsessions. Trigger avoidance ranges from subtle adaptations (using sleeves to touch door handles, using fewer fingers on surfaces)…

Trigger Hierarchy(also: Exposure Hierarchy, Fear Hierarchy, Fear Ladder)

A ranked list of situations, objects, or thoughts that trigger OCD anxiety, ordered from least to most distressing as measured by subjective distress ratings (SUDS). Trigger hierarchies are a foundational tool in Exposure and Response Prevention therapy, guiding the gradual…

Trigram(also: 3-gram)

A sequence of three consecutive words used in statistical language modeling for word prediction. Trigram models predict the next word based on the two preceding words, capturing more context than simpler unigram (single word) or bigram (two word) models. In AAC word prediction,…

Trimodal Feedback(also: Triple-Modality Feedback)

A form of interface feedback that delivers information through three simultaneous sensory channels — typically auditory, haptic, and visual. Trimodal feedback offers the highest level of redundancy in multimodal interface design, ensuring that users can perceive system responses…

Triple Jeopardy

A framework describing the compounded discrimination faced by individuals who hold three intersecting marginalised identities — in Bowleg et al.'s original formulation, Black lesbians navigating racism, sexism, and heterosexism simultaneously. In accessibility contexts, the…

Tritanomaly(also: Tritan Anomalous Trichromacy)

A rare type of colour vision deficiency where the short-wavelength (blue) cone cells have a shifted sensitivity range. Tritanomaly results in reduced ability to distinguish blue from yellow. It is the rarest form of anomalous trichromacy and is less commonly addressed in…

Tritanopia(also: Tritan Dichromacy, Blue-Blind)

A rare type of colour vision deficiency caused by the complete absence of short-wavelength (blue) cone cells in the retina. People with tritanopia have difficulty distinguishing blue from yellow and blue from green. Tritanopia is much less common than protan or deutan CVD types…

Trouble-Indicating Behavior(also: TIB, Trouble Source-Repair)

Verbal or nonverbal behaviors that signal confusion, misunderstanding, or difficulty in communication. In research on dementia and human-robot interaction, TIBs are categorized into types including: requests for repetition, requests for clarification, metalinguistic comments ("I…

Trove

An online discovery service operated by the National Library of Australia that aggregates digitised books, newspapers, images, archives, and other cultural-heritage content, with integrated OCR-error correction tools. Trove is frequently cited in accessibility and crowdsourcing…