Glossary

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Tactile Modelling(also: Tactile Demonstration, Touch-Based Instruction)

A teaching technique used in movement and dance education for blind and low-vision learners, where the student physically explores the teacher's body position by touch to understand the shape, form, and spatial relationships of a pose or movement. While effective for…

Tactile Overlay(also: Touch Overlay, Tactile Screen Overlay)

A physical sheet or frame placed on top of a touchscreen or flat surface that provides raised tactile landmarks, borders, buttons, and contextual information for users who are blind or have low vision. Tactile overlays can be made from laser-cut cardboard, 3D printed materials,…

Tactile Paving(also: Tactile Ground Surface Indicators, TGSI, Detectable Warning Surface)

A system of textured ground surface indicators installed on footpaths, train platforms, and building floors to assist pedestrians who are blind or have low vision with navigation and hazard detection. Tactile paving typically uses two patterns: raised dots (truncated domes) to…

Tactile Perception(also: Cutaneous Perception, Touch Perception)

Tactile perception is the process of perceiving and interpreting information through the sense of touch, encompassing both cutaneous perception (sensing through the skin in a stationary process, detecting texture, pressure, vibration, temperature, and pain) and haptic perception…

Tactile Printer(also: Braille Embosser, Tactile Embosser)

A device that produces raised-line graphics and text on paper or other media, enabling people who are blind or have low vision to access visual information through touch. Tactile printers work by embossing dots or lines onto heavy paper, or by using thermal processes with…

Tactile Reading(also: Touch Reading)

The process of reading text through the sense of touch, primarily using the fingertips to perceive raised characters such as braille. Tactile reading requires distinct perceptual and cognitive skills from visual reading, including fine tactile discrimination, spatial pattern…

Tactile Rendering

The process of converting visual or spatial information into a tactile format that can be perceived through touch by blind or visually impaired users. Tactile rendering involves decisions about how to represent 3D objects, spatial relationships, depth, and visual attributes…

Tactile Replica(also: 3D Replica, Touchable Replica, Haptic Replica)

A physical reproduction of an artwork or exhibit object, often created using 3D printing or traditional sculpting techniques, designed to be touched and explored by hand. Tactile replicas are a key accessibility strategy in museums and galleries for blind and low vision…

Tactile Screenshots(also: Tactile UI Representations)

Embossed or raised representations of graphical user interface screens that allow blind users to explore software layouts through touch. Tactile screenshots preserve the spatial arrangement of UI elements such as buttons, icons, text areas, and navigation elements, enabling…

Tactile Semiotics

The study and theory of how meaning is communicated through touch, drawing on broader semiotic principles that every media channel has rules or encodings for conveying meaning. Tactile semiotics examines how physical properties of tactile objects—such as roughness, height,…

Tactile Signage(also: Tactile Signs, Touch-Readable Signs)

Signs designed to be read by touch, typically featuring raised lettering, Braille text, or tactile symbols. Required in many jurisdictions under accessibility legislation such as the Americans with Disabilities Act (ADA), tactile signage is placed at standard locations like room…

Tactile Stimulation(also: Tactile Feedback, Cutaneous Stimulation)

Tactile stimulation refers to the use of physical sensations delivered to the skin to convey information, typically through vibrations, pin arrays, textures, or pressure changes. In assistive technology, tactile stimulation is fundamental to braille displays, haptic interfaces,…

Tactile Texture(also: Haptic Texture)

The surface quality of a material or graphic element as perceived through touch, characterized by properties such as roughness, smoothness, density, height, pattern regularity, and directionality. In tactile graphics, different textures are used to represent different regions or…

Tactile User Interface(also: Tactile UI, TUI)

A user interface designed to be operated and understood through the sense of touch, enabling interaction for blind and low vision users. Tactile user interfaces may include physical buttons with tactile markings, raised icons, textured surfaces that indicate different functional…

Tactile Working Memory(also: Haptic Working Memory, Touch Working Memory)

The cognitive system responsible for temporarily storing and manipulating tactile information received through the sense of touch. Similar to visual and auditory working memory, tactile working memory has limited capacity (typically 2-5 items depending on conditions) and is…

Tactile graphic production(also: Tactile image creation, Accessible graphic transcription)

The process of converting visual images — such as textbook diagrams, charts, maps, and illustrations — into raised tactile representations that can be explored by touch. Production methods include swell paper (microcapsule paper heated to raise printed lines), embossing,…

Tactile graphics(also: Raised-line graphics, Touch graphics)

Physical representations of visual information using raised surfaces, textures, and patterns that can be explored through touch. Tactile graphics are essential for conveying spatial and graphical information — maps, charts, diagrams, mathematical graphs — to blind and visually…

Tactile learning(also: Haptic learning, Touch-based learning)

An educational approach that uses the sense of touch as a primary channel for acquiring knowledge, developing skills, and understanding concepts. For BLV students, tactile learning is essential — braille reading, tactile diagrams, physical manipulatives, and hands-on crafts like…

Tactile paving(also: Tactile ground surface indicators, TGSI, Detectable warning surface)

A system of textured ground surfaces installed on footpaths, transit platforms, and pedestrian crossings to provide navigational cues to people with visual impairments through the sense of touch underfoot or via a white cane. Standardised patterns include raised dots (warning of…

Tactile relief(also: 2.5D relief, Tactile relief model)

A physical representation that preserves depth information and surface textures from a two-dimensional image, creating a raised surface that can be explored by touch. Unlike flat raised-line drawings or tactile diagrams, tactile reliefs convey spatial relationships, depth…

Tactile-First Strategy(also: Touch-Based Strategy, Tactile-First Approach)

An approach to completing tasks that prioritizes touch and physical sensation as the primary sensory channel for guidance, feedback, and assessment. In accessibility contexts, tactile-first strategies are developed by people with vision impairments to navigate tasks…

Tactilization(also: Tactile Rendering, Haptic Rendering)

The process of converting visual or abstract information into tactile representations that can be perceived through the sense of touch. In accessibility, tactilization transforms content such as web page layouts, data visualizations, or text emphasis into patterns of vibration,…

Tacton(also: Tactile Icon, Vibrotactile Pattern)

A structured and abstract vibrotactile message designed to communicate complex information to users non-visually, analogous to how icons communicate information visually or earcons communicate through audio. Tactons encode information through vibration parameters such as rhythm,…

Tactor(also: Vibrotactile Actuator, Tactile Actuator, Vibration Motor)

A small electromechanical device that produces vibrations against the skin to convey information through the sense of touch. Tactors are the fundamental components of tactile displays and wearable haptic devices, commonly used in electronic travel aids, navigation belts, and…

Tadoma(also: Tadoma Method)

A tactile method of communication used by individuals who are deafblind, in which the receiver places their hand on the speaker's face — thumb lightly on the lips and fingers along the jawline and cheek — to feel the movements of speech including lip movements, vibrations, and…

Tag Order(also: Source Order, DOM Order, Reading Order)

The sequential order in which HTML elements appear in the source code of a web page, which determines the order in which screen readers and other assistive technologies present content to users. When web pages use CSS or layout tables to position content visually, the tag order…

Tag Tree(also: PDF Tag Structure, Structure Tree, Tagged PDF Structure)

The hierarchical structure of semantic tags embedded within a PDF document that defines the logical organization and reading order of its content. A tag tree is analogous to the DOM (Document Object Model) in HTML — it identifies headings, paragraphs, lists, tables, figures, and…

Tagged PDF(also: Structured PDF, Accessible PDF)

A PDF document that contains semantic structure tags defining the logical reading order, headings, paragraphs, lists, tables, and figures — enabling screen readers and other assistive technologies to navigate and interpret the content meaningfully. Without tags, a PDF is…

Tailorability(also: Tailorable systems)

A design property, central to infrastructuring theory, that allows users to configure, extend, or repurpose a system after deployment to fit their local use context. Tailorability goes beyond 'customisation' by anticipating that users will adapt tools in ways their original…

TalkBack(also: Android TalkBack, Google TalkBack)

The built-in screen reader for Android devices, developed by Google as part of the Android Accessibility Suite. TalkBack provides spoken feedback, vibration, and other audible cues to help blind and visually impaired users navigate their devices without seeing the screen. Users…

Talking Browser(also: Talking Web Browser, Speaking Browser)

A historical term for a specialised web browser that converts on-screen content into synthesised speech, enabling blind and low-vision users to browse the web through audio rather than through a separate screen reader layered over a visual browser. Talking browsers such as IBM…

Talking Head(also: Virtual Talking Head, Animated Face, 3D Talking Head)

A talking head is a computer-generated 3D or 2D animated representation of a human face and articulatory system that produces visible speech movements synchronised with audio output. In accessibility and speech therapy contexts, talking heads are particularly valuable because…

Talking Lights

Talking Lights is a commercial location-signalling system that modulates ordinary fluorescent light fixtures to transmit an inaudible digital signal, which a hand-held receiver carried by a blind user decodes into spoken information about the current location (for example, a…

Talking Mats

A visual communication framework that uses a textured mat and sets of picture symbols to help people express their views on topics that matter to them. Developed at the University of Stirling, Talking Mats provides a structured way for people who find it difficult to communicate…

Talking Signs(also: Talking Sign)

An assistive technology system that uses infrared (IR) frequency modulated voice signals to transmit spoken information about signage to people with vision loss. Developed by the Smith-Kettlewell Eye Research Institute in 1992, Talking Signs broadcast recorded messages that can…

Talking-Head Video(also: Talking Head)

A common educational video format in which a presenter speaks directly to the camera, typically filling the frame, with no or few accompanying visuals. For d/Deaf and Hard-of-Hearing learners, talking-head videos are often low in useful visual content - the speaker's face must…

Tangible Design Language(also: Physical Design Language)

An approach to design communication that uses physical objects, props, and prototypes to enable participants to express their needs, ideas, and preferences through hands-on interaction rather than abstract verbal or written descriptions. Tangible design languages are especially…

Tangible Interface(also: Tangible User Interface, TUI)

A user interface that uses physical objects as representations and controls for digital information, allowing users to interact through touch and manipulation of tangible artifacts. In accessibility contexts, tangible interfaces have been used for braille literacy education…

Tangible Programming(also: Physical Programming, Tangible Coding, Tactile Programming)

A programming approach that uses physical objects — such as blocks, cards, or robots — that users can manipulate with their hands to create programs, rather than typing code or dragging on-screen elements. Tangible programming is particularly valuable for students with visual…

Tangible Technology(also: Tangible Interface, Tangible User Interface, TUI)

Technology that connects physical objects to digital systems, allowing users to interact with computing through touching, manipulating, and moving real-world objects rather than through screens or keyboards. Tangible technologies are particularly valuable in accessibility…

Tangible User Interface(also: TUI, Physical Interface)

An interface in which users interact with digital information through physical objects and surfaces in the real world. Tangible user interfaces bridge the gap between digital and physical by giving digital data a physical form that can be grasped, moved, and manipulated. For…

Tangible interaction(also: Tangible user interface, TUI, Physical computing)

An interaction paradigm in which users manipulate physical objects and materials to interact with digital information, bridging the gap between the physical and digital worlds. Tangible interfaces leverage people's existing skills in manipulating physical objects, making them…

Tangram Workstation(also: Tangram)

A LibreOffice extension for creating tactile graphics collaboratively. Tangram enables sighted users to design graphics while providing real-time tactile feedback to blind reviewers through a connected pin-matrix display. The tool includes a palette of validated tactile fill…

Tap-to-Hear(also: Point-to-Hear, Tap-to-Listen, Point-and-Click Exploration)

An interaction paradigm used in tactile graphic readers and touch-based accessibility tools where users touch or tap on elements of a tactile graphic to trigger spoken audio descriptions of the element beneath their finger. Tap-to-hear is the current standard approach for…

TapTapSee

An AI-enabled visual assistance app designed for blind and low vision users that identifies objects through photos taken with a smartphone camera. Users double-tap their screen to take a photo, and the app uses image recognition to identify and describe the object. TapTapSee is…

Tappability(also: Tap Target, Tappable)

The property of a user interface element that indicates whether it can be activated by tapping on a touchscreen device. Tappability is a key concern in mobile accessibility because elements that appear tappable but are not (or vice versa) create barriers for users who rely on…

Target Ambiguity(also: Command Ambiguity)

A usability problem in voice and speech-based interfaces where a user's spoken command could refer to more than one element on the screen. For example, if multiple buttons share the same label in different parts of an application, saying that label creates ambiguity about which…

Target Expansion(also: Expanding Targets, Dynamic Target Sizing)

An interaction technique where clickable interface elements dynamically grow in size as the cursor approaches, making them easier to select while conserving screen space when not being targeted. Research shows target expansion can reduce selection times by up to 14% and error…

Target Highlight Time(also: THT)

A performance measure used in human-computer interaction research that captures the time elapsed between when a user positions a pointer over a target and when they initiate an action on that target, such as clicking or dragging. THT reflects how quickly a user can recognize and…

Target Selection(also: Target Acquisition, Pointing)

The fundamental interaction task of moving a cursor or pointer to a specific location on screen and confirming selection, such as clicking a button or link. Target selection difficulty is affected by target size, distance to target, and user motor abilities—relationships…