Glossary

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Speed Dial(also: One-touch Dialing, Quick Dial)

Speed dial is a mobile or landline phone feature that lets a user place a call to a preset contact by pressing one or two assigned digits rather than entering a full phone number. Originally introduced as a convenience feature, speed dial functions as a meaningful accessibility…

Spell Checker(also: Spellchecker, Spelling Checker)

Software that identifies and suggests corrections for misspelled words in text. Standard spell checkers often fail to catch errors made by people with dyslexia because dyslexic spelling errors differ from typical misspellings — they may include real-word substitutions (e.g.,…

Split-Tap Gesture(also: Split Tap)

A two-finger touchscreen gesture where one finger holds position on an object while a second finger taps elsewhere on the screen to activate or select it. Originally developed for the Slide Rule screen reader, the split-tap gesture was adopted by mobile screen readers like…

Spoken Dialog System(also: SDS, Voice Dialog System, Conversational AI)

A computer system that uses speech as both input and output to conduct goal-oriented conversations with users. Unlike simple voice command systems, spoken dialog systems can handle multi-turn exchanges, track conversation context, manage misunderstandings, and adapt to user…

Spoken Dialogue System(also: SDS, Voice Dialogue System)

A computer system that communicates with users through spoken natural language, allowing them to interact via voice rather than visual or manual interfaces. Spoken dialogue systems are used in telecare, customer service, and home care applications, and are particularly relevant…

Stance-Control Orthosis(also: Stance-control KAFO, SCO, Stance-control knee-ankle-foot orthosis)

A class of knee-ankle-foot orthoses that lock the knee during the stance (weight-bearing) phase of gait to prevent buckling, but unlock it during the swing phase to allow natural knee flexion. Stance-control devices detect gait phase through joint-angle sensors,…

Steering Law(also: Accot-Zhai Steering Law)

A predictive model of human movement describing the time required to navigate a cursor through a constrained path, such as a tunnel or curved corridor on screen. Proposed by Accot and Zhai as an extension of Fitts's Law, the Steering Law accounts for tasks where the user must…

Stenographic Keyboard(also: Steno Machine, Stenotype, Shorthand Keyboard)

A specialized keyboard used by CART captioners and court reporters that allows simultaneous pressing of multiple keys to represent syllables, words, or phrases in a single stroke, enabling transcription speeds of 200+ words per minute. Each captioner maintains a personal…

Stenotype(also: Stenography, Shorthand Typing, Machine Shorthand)

A specialised text-entry method that uses a keyboard with fewer keys than a standard QWERTY layout, where multiple keys are pressed simultaneously (chording) to represent phonetic sounds, syllables, or entire words. Stenotype enables trained operators to achieve speeds of…

Step-by-Step Device(also: Sequential Message Device, Step-by-Step Communicator, SBS)

A simple, single-switch augmentative and alternative communication (AAC) device that stores a sequence of pre-recorded voice messages and plays them back one at a time with each button press. Step-by-step devices are categorised as "low-tech" or "mid-tech" AAC because they…

Stepwise pointing(also: Recursive target acquisition, Tile-based pointing)

A mouse emulation technique in which the screen is divided into a grid of tiles, the user selects a tile to zoom into it, the tile subdivides into smaller subtiles, and this process repeats until the desired screen location is reached at pixel-level precision. Stepwise pointing…

Stereo Panning(also: Audio Panning, Pan)

The technique of distributing a mono sound signal between the left and right channels of a stereo output to create the perception that the sound originates from a specific horizontal position in space. A fully left-panned sound plays only in the left ear, a centered sound plays…

Stereo Vision(also: Stereoscopic Vision, Stereo Camera System, Stereopsis)

A computer vision technique that uses two or more cameras positioned at slightly different viewpoints to extract three-dimensional depth information from a scene, mimicking the way human binocular vision perceives depth. In assistive technology, stereo vision systems have been…

Stereoscopic Camera(also: Stereo Camera, Depth Camera, 3D Camera)

A camera system that uses two or more lenses to capture images from slightly different perspectives, mimicking human binocular vision to compute depth information (disparity maps). In accessibility applications, stereoscopic cameras are used in assistive devices for visually…

Sticky Keys(also: Sequential Key Entry)

An operating system accessibility feature that allows users to press modifier keys (Shift, Ctrl, Alt, Command) sequentially rather than simultaneously, making keyboard shortcuts accessible to people who can only press one key at a time. Sticky Keys is built into Windows, macOS,…

Structural Abstraction(also: Formula Abstraction, Expression Collapsing)

Structural abstraction is an accessibility technique that simplifies complex visual structures — particularly mathematical formulas — by initially collapsing sub-expressions into symbolic summaries and allowing users to progressively expand and explore them at their own pace.…

Structured Audio(also: Structured Digital Audio)

Structured audio refers to digital audio content that has been encoded with hierarchical markers and metadata, allowing non-sequential access to specific segments such as chapters, sections, paragraphs, and phrases. Unlike linear audio recordings (such as traditional audio…

Stylus(also: Digital Pen, Active Pen)

A pen-shaped input device used to interact with touchscreens, tablets, and other digitizer surfaces. Unlike finger touch, styluses provide a smaller contact point for precise selection, and active styluses can detect pressure, tilt, and hover states. For accessibility, styluses…

Subvocal Input(also: Subvocal Control, Subvocalisation Input)

An input method that uses very quiet or nearly silent vocalisations — sounds produced with minimal vocal effort that are typically inaudible to nearby people. Subvocal input includes techniques such as humming, whispering, or producing sounds detectable only by bone-conduction…

Suitcase Robot(also: Suitcase-shaped robot, Robotic suitcase)

A class of autonomous navigation robots housed inside a rolling suitcase or carry-on-shaped enclosure, designed so that a blind or low-vision user can grip the handle and be guided to a destination while appearing to any onlooker to simply be walking with a piece of luggage. The…

Surface Electromyography(also: sEMG, Surface EMG)

A non-invasive technique for measuring the electrical activity produced by skeletal muscles, using electrodes placed on the skin over the muscle. Surface EMG is used in biomechanics, prosthetic control, rehabilitation, and — increasingly — as an input modality for accessible…

Surface Haptics(also: Surface Haptic Technology)

A branch of haptic technology that creates tactile sensations directly on a flat surface, such as a touchscreen, by modulating the friction between a fingertip and the display. Unlike conventional vibration motors that shake the entire device, surface haptics produces localised…

Surround sound(also: Multichannel audio, 5.1 audio, 7.1 audio)

An audio reproduction technique that uses multiple speaker channels arranged around the listener to create an enveloping sound field. Common configurations include 5.1 (five speakers plus a subwoofer) and 7.1 (seven speakers plus a subwoofer), where speakers are placed at…

Swarm robotics(also: Multi-robot systems)

A field of robotics involving the coordination of multiple simple robots that work together as a group, inspired by collective behaviours in nature such as ant colonies or bird flocking. Individual robots follow simple rules, but their collective behaviour produces complex,…

Swell Form(also: Capsule Paper, Microcapsule Paper, Swell Touch Paper)

A tactile graphics production method using special heat-sensitive paper coated with microcapsules. When black ink is printed on the paper and passed through a heating machine, the dark areas absorb heat and swell, creating raised tactile surfaces. Swell Form is commonly used in…

Swell Paper(also: Capsule Paper, Microcapsule Paper, PIAF Paper)

A special paper coated with heat-sensitive microcapsules that swell when exposed to heat, creating raised tactile surfaces from printed black areas. When passed through a heating device (such as a PIAF — Pictures In A Flash — machine), dark-printed lines and shapes become raised…

Switch(also: Adaptive Switch, Accessibility Switch)

An assistive technology input device that is activated by a single action such as pressing, squeezing, blowing, blinking, or moving a body part. Switches are designed for people with significant motor impairments who cannot use standard keyboards, mice, or touchscreens. They…

Switch Access(also: Switch Control, Switch Scanning)

A method of computer and device interaction that uses one or more switches as input devices, designed for people who cannot use standard keyboards, mice, or touchscreens due to motor impairments. Switch access is built into major operating systems (iOS Switch Control, Android…

Switch Keyboard(also: Scanning Keyboard, On-Screen Scanning Keyboard)

A switch keyboard is a virtual keyboard interface designed for people with severe motor disabilities who cannot use a standard keyboard or pointing device. It works through a scanning mechanism: a cursor automatically moves across rows and columns of the keyboard, and the user…

Switch Scanning(also: Scanning Mode, Auto Scanning)

An input method for assistive technology where options are sequentially highlighted (scanned) and the user activates a single switch to select the currently highlighted item. This enables people with severe motor disabilities to access computers, communication devices, and other…

Switch Scanning(also: Switch Access, Scanning Input)

An alternative input method in which items on a screen are sequentially highlighted and the user activates a switch to select the desired item when it is highlighted. Switch scanning is used by people with significant motor impairments who cannot use direct touch, a mouse, or a…

Symbol Selection Set(also: Symbol Board, Communication Board)

A structured collection of graphic symbols, words, or phrases arranged in a grid or other layout for use in augmentative and alternative communication (AAC). Users select symbols to compose messages, with each symbol representing a word, phrase, concept, or action. Selection…

Symbol-Based Communication(also: Picture-Based Communication, Graphic Symbol Communication)

A form of augmentative communication that uses visual symbols — including pictures, photographs, line drawings, or icons — to represent words, concepts, or messages. Symbol-based communication is particularly useful for people with limited literacy, intellectual disabilities, or…

Symbol-based AAC(also: Picture-based AAC, Pictographic AAC, Picture Communication Symbols)

Symbol-based AAC refers to augmentative and alternative communication systems whose vocabulary is represented by graphic symbols, line drawings, photographs, or pictograms rather than (or alongside) written words. Users select symbols on a paper board, a dedicated…

Symbolic Communication(also: Symbol-Based Communication)

Communication that uses symbols — including spoken words, written text, manual signs, pictures, or graphic icons — to represent meanings, objects, actions, or concepts. Developing symbolic communication is a critical milestone for emergent communicators, as it enables more…

Symptom Tracking(also: Symptom Monitoring, Symptom Logging)

The systematic recording of mental health symptoms, behaviors, triggers, and associated contexts over time to build self-awareness, identify patterns, and measure treatment progress. For OCD, symptom tracking may include logging triggers, compulsive behaviors, anxiety levels…

Synthesized Speech(also: Synthetic Speech, Speech Synthesis, TTS Output)

Computer-generated speech produced by text-to-speech (TTS) engines that convert written text into spoken audio output. Synthesized speech is the primary means by which screen readers convey on-screen content to blind and visually impaired users. While modern TTS voices have…

Synthesized Video Description(also: TTS Video Description, Text-to-Speech Description, Synthesized Audio Description)

An audio description for video content that is generated using text-to-speech (TTS) technology rather than recorded by a human narrator. A describer writes a text script describing the visual elements of a video, and speech synthesis software converts this text into spoken…

Synthetic Speech(also: Artificial Speech, Computer-generated Speech)

Speech that is artificially produced by computer systems rather than recorded from human speakers. Synthetic speech is the output of text-to-speech systems and is fundamental to screen readers and voice assistants. Modern synthetic speech uses various generation methods…

Synthetic Voice(also: Artificial Voice, Computer-Generated Voice, TTS Voice)

A digitally generated voice produced by text-to-speech technology, used by individuals with speech impairments as an alternative means of verbal communication. People who rely on synthetic voices for presentations, phone calls, or daily conversation must often invest…

System Access(also: SA, System Access to Go, SA To Go)

A screen reader for Windows developed by Serotek Corporation that was notable for offering a free version and a portable "To Go" edition that could run from a USB drive without installation. System Access was designed to provide an affordable alternative to commercial screen…

T9(also: Text on 9 Keys, Tegic T9)

T9 (Text on 9 Keys) is a dictionary-based predictive text-entry method developed by Tegic Communications in the 1990s for mobile phone keypads with multiple letters assigned to each numeric key. Rather than pressing a key multiple times to cycle through letters (the older…

TTY(also: TDD, Telecommunications Device for the Deaf, Text Telephone)

A text-based telecommunications device that enables people who are deaf, hard of hearing, or have speech disabilities to communicate over telephone lines by typing messages that are displayed on a screen or printed on paper. TTY devices were the primary means of telephone…

TTY Relay Service(also: Telecommunications Relay Service, TRS, Text Telephone Relay)

A telecommunications service that enables people who are deaf, hard of hearing, or have speech disabilities to communicate by telephone through a relay operator who converts between text and voice. Users type messages on a TTY (teletypewriter) device, and the relay operator…

Table Navigation Mode(also: Table Navigation)

A screen reader feature that allows users to navigate within data tables by moving a virtual cursor cell-by-cell in two dimensions — by row and by column — rather than reading content linearly. Introduced by Ogane and Asakawa in 1998 and subsequently adopted by virtually all…

Table-to-Prose(also: Table-to-Prose Transformation, Tabular Data Narration)

The process of converting structured tabular data into natural language prose descriptions that can be easily understood when read aloud or presented through speech synthesis. Table-to-prose transformation goes beyond simple cell-by-cell linearization by constructing coherent…

Tablet Input(also: Graphics Tablet, Pen Tablet, Digitizer Tablet)

An input device consisting of a flat surface that detects the position and movement of a stylus or digital pen, translating physical writing and drawing motions into digital input. Graphics tablets (such as those made by Wacom) provide an alternative to mouse input that…

Tablet PC(also: Tablet Computer, Pen Tablet)

A portable computing device featuring a touchscreen display that can be operated with fingers, a stylus, or both. For accessibility purposes, tablets offer several advantages: adjustable screen angle and position, portability for use in comfortable positions, direct manipulation…

Tactile Aid(also: Tactile Learning Aid, Tactile Tool)

A physical object designed to convey information through touch, used to make visual or abstract concepts accessible to people who are blind or have low vision. Tactile aids can include raised-line drawings, textured surfaces, 3D-printed models, and laser-cut representations of…

Tactile Animation(also: Animated Tactile Graphics, Tactile Motion Graphics)

A sequence of tactile images displayed over time on a refreshable tactile display to convey motion, change, or dynamic processes through touch. Unlike static tactile graphics, tactile animations allow blind and low-vision users to perceive movement, temporal progression, and…