Glossary

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Ear-EEG(also: Around-the-Ear EEG, cEEGrid)

Ear-EEG refers to electroencephalography (EEG) recorded using electrodes placed in and around the ear canal rather than on the scalp. Consumer-grade ear-EEG devices such as cEEGrid sensors are unobtrusive, easy to wear without hair preparation, and suitable for everyday…

Earcon(also: Auditory icon)

A brief, distinctive sound used in a user interface to convey information, status, or feedback non-visually. Earcons serve a similar function to visual icons but through the auditory channel. In accessible interfaces, earcons can augment or replace visual cues — for example, a…

Early Blind(also: Congenitally Blind, Early Onset Blindness)

A person who was born blind or lost their vision before approximately age 5-7, before visual memories and spatial concepts based on vision were fully established. Early blind individuals develop spatial understanding entirely through non-visual senses—touch, hearing,…

Early Intervention(also: EI, Early Childhood Intervention)

Services and support provided to infants and young children (typically birth to age 3 or 5) with developmental delays or disabilities, and their families. For DHH children, early intervention is critical and includes sign language instruction, speech-language therapy,…

Early Intervention(also: EI, Early Childhood Intervention)

Early intervention refers to services and supports provided to infants and young children (typically from birth to age six) who have developmental delays, disabilities, or conditions that place them at risk for developmental difficulties. The aim is to reduce or compensate for…

Early intervention(also: Early childhood intervention, EI)

A system of services and supports provided to infants and young children with developmental delays or disabilities, typically from birth to age three, and their families. Early intervention can include speech therapy, occupational therapy, physical therapy, and behavioral…

Early-Onset Dementia(also: Young-Onset Dementia, Working-Age Dementia)

Dementia diagnosed before the age of 65, affecting individuals who are often still in the workforce and digitally active. Early-onset dementia presents unique accessibility challenges because affected individuals typically have established digital literacy and strong…

Earmarking(also: Money Earmarking)

A financial-management practice, studied by sociologist Viviana Zelizer, in which people mentally or materially separate money into distinct categories tied to specific purposes (rent, groceries, savings goal, treats). Earmarking can take physical form — separate envelopes,…

Easy Language(also: Easy-to-Read, Leichte Sprache, Easy Read)

A simplified form of written language designed to make information accessible to people with reading difficulties, including those with intellectual disabilities, prelingual hearing impairments, learning disabilities, low literacy, or limited proficiency in the language. Easy…

Easy Read(also: Easy-to-Read, Easy Language, Plain Language for Cognitive Accessibility)

A method of presenting written information in a way that is accessible to people with intellectual disabilities, learning difficulties, or low literacy. Easy Read uses short sentences, common everyday vocabulary, active voice, and clear structure, often accompanied by images or…

Easy-to-Read(also: E2R, Easy Read, ETR)

A content-simplification approach that presents information in short sentences, plain vocabulary, and clear structure to support readers with cognitive disabilities, learning difficulties, low literacy, or who are reading in a non-native language. Easy-to-Read is increasingly…

Eccentric Viewing(also: Eccentric Fixation)

A visual strategy used by people with central vision loss (such as from macular degeneration) in which they learn to use a peripheral area of the retina — called a preferred retinal locus (PRL) — to look at objects instead of the damaged central macula. Eccentric viewing…

Eccentric viewing(also: Preferred retinal locus, PRL)

A viewing strategy used by people with central vision loss (such as from macular degeneration) in which they learn to look slightly off-center to use a healthier area of the retina instead of the damaged macula. The part of the retina they train themselves to use is called the…

Echolalia(also: Echoing, Echolalic Speech)

The repetition or echoing of words, phrases, or sounds spoken by others, commonly observed in individuals with autism spectrum disorder and some other developmental conditions. Echolalia can be immediate (repeating something just heard) or delayed (repeating something heard…

Echolocation(also: Human echolocation, Active echolocation)

The ability to determine the location and characteristics of objects by emitting sounds and interpreting their echoes. While commonly associated with bats and dolphins, many blind and low-vision individuals develop echolocation skills for spatial navigation, using self-generated…

Ecological Metaphor(also: Ecological Validity, Ecological Mapping)

A design principle in sonification and auditory display where the mapping between data and sound aligns with users' real-world sensory and cognitive experience. For example, mapping obstacle distance to pulse rate (like sonar or parking sensors), height to pitch (higher…

Ecological Momentary Assessment(also: EMA, Experience Sampling)

A research and clinical method that involves repeatedly sampling people's behaviors, experiences, and physiological states in real time within their natural environments. EMA typically uses smartphone prompts to ask users to report their current thoughts, feelings, activities,…

Ecological Systems Theory(also: Bronfenbrenner's Ecological Model, Bioecological Model)

A developmental psychology framework created by Urie Bronfenbrenner that describes how individuals are influenced by multiple nested environmental systems: the microsystem (immediate settings like home and work), mesosystem (connections between microsystems), exosystem (indirect…

Ecological Validity

In user experience research, the degree to which a mediated experience feels natural, realistic, and believable—as if it could occur in a real-world context. In immersion measurement frameworks like the ITC Sense of Presence Inventory, ecological validity is a subscale alongside…

Ecological validity(also: Real-world validity)

The degree to which research findings from controlled laboratory settings accurately reflect behaviour and performance in real-world everyday contexts. In accessibility research, ecological validity is a critical concern because laboratory conditions — structured tasks, quiet…

Ecology of Protections(also: Layered Protection Ecosystem)

A multi-layered framework for safeguarding vulnerable users from harmful digital content by implementing protections at multiple levels of the technology stack simultaneously. For photosensitive users, this ecosystem encompasses six layers: policy-level (legislation and…

Edge Computing(also: Edge AI, Edge Intelligence)

Edge computing is a computing paradigm where data processing occurs on devices physically close to the user rather than in centralized cloud servers. For accessibility applications, edge computing offers important advantages including reduced latency for real-time assistive…

Edge enhancement(also: Edge detection, Contour enhancement)

An image processing technique that identifies and highlights the boundaries between objects in a visual scene, typically rendering them as bright lines against a dark background or overlaying them on the original image. For people with low vision, edge enhancement can make…

EdgeWrite(also: Edge Write)

A gestural text entry method that uses the physical edges and corners of a square input area to guide character formation. Unlike traditional handwriting recognition that analyzes the full path of a stroke, EdgeWrite recognizes characters based on the sequence of corners hit,…

Edinburgh Postnatal Depression Scale(also: EPDS)

The Edinburgh Postnatal Depression Scale (EPDS) is a validated 10-item self-report screening questionnaire designed to identify symptoms of depression during pregnancy and in the postpartum period. Each item is scored 0–3, with a total score of 10 or above typically indicating…

Editorial Enunciation(also: Visual Enunciation)

A semiotic concept describing how the visual layout and organisation of an interface communicates meaning beyond the content it contains. Editorial enunciation encompasses the spatial arrangement, sizing, positioning, and visual hierarchy of interface elements — all of which…

Educational Technology(also: EdTech, Learning Technology, Instructional Technology)

The use of technological tools and resources to facilitate teaching and learning. In accessibility contexts, educational technology encompasses assistive tools designed to support students with disabilities, such as screen readers, refreshable Braille displays, auditory graphing…

Educational Video(also: Instructional Video, Video Lecture)

Video content created to teach - including talking-head lectures, screencasts, animations, hand-drawn (Khan-style) explanations, recorded classroom sessions, programming/coding demonstrations, interviews, and slide-based presentations. Accessibility of educational video depends…

Edutainment(also: Educational Entertainment, Learning Games)

Content or applications that combine education with entertainment, typically through games, interactive media, or engaging activities designed to teach skills while keeping users motivated and engaged. In the accessibility context, edutainment apps must balance engaging visual…

Egocentric(also: Egocentric Reference Frame, Body-Centred Reference Frame)

A spatial reference frame in which locations and directions are defined relative to the observer's own body position and orientation. For example, "turn left," "take one step forward," or "the door is on your right" are egocentric descriptions. People with visual impairments…

Egocentric Camera(also: First-Person Camera, POV Camera)

A camera that captures video from the wearer's point of view, typically mounted on the head, glasses, or chest. Egocentric video captures what the user sees or interacts with, making it valuable for activity recognition, assistive technology, and accessibility research. For BLV…

Egocentric Spatial Reasoning(also: First-Person Spatial Understanding, User-Relative Spatial Reasoning)

The ability of a system to understand and describe the spatial positions of objects relative to the user's body and perspective, rather than from a bird's-eye or absolute reference frame. For AI systems assisting blind travelers, egocentric spatial reasoning is critical —…

Ehlers-Danlos Syndrome(also: EDS)

A group of heritable connective tissue disorders characterized by joint hypermobility, skin hyperelasticity, and tissue fragility. EDS often leads to frequent joint dislocations, chronic pain, and difficulty with physical tasks like gripping objects, holding books, or opening…

Eigenfaces

A computer vision technique for face recognition that uses Principal Component Analysis to represent faces as a linear combination of standardized face components (eigenvectors derived from a training set of face images). Developed by Turk and Pentland in 1991, Eigenfaces was…

Eight-Dot Braille(also: 8-Dot Braille, Computer Braille)

An extended braille system that adds two additional dots below the standard six-dot braille cell, creating a 2x4 matrix of eight dots that can represent 256 unique characters (compared to 64 in standard 6-dot braille). Eight-dot braille is primarily used with refreshable braille…

Ekman Basic Emotions(also: Basic Emotions, Ekman's Six Basic Emotions)

A taxonomy proposed by psychologist Paul Ekman that identifies six cross-culturally recognisable emotional expressions — happiness, sadness, anger, fear, disgust, and surprise — as the building blocks of facial affect. The model has been foundational for computer-vision…

Electrical Muscle Stimulation(also: EMS, Neuromuscular Electrical Stimulation, NMES)

A technique that uses electrical impulses delivered through surface electrodes to elicit muscle contractions. EMS is used therapeutically for muscle re-education, spasticity management, and rehabilitation, and has been explored in HCI as an output modality — for example, guiding…

Electrodermal Activity(also: EDA, Galvanic Skin Response, GSR)

The variation of electrical conductance in the skin caused by sweat gland activity, which is controlled by the sympathetic nervous system. EDA is used as a physiological measure of emotional arousal and stress, with applications in accessibility research for understanding the…

Electroencephalography(also: EEG)

A non-invasive method of recording electrical activity of the brain using electrodes placed on the scalp. In assistive technology, EEG is the primary sensing technology behind brain-computer interfaces (BCIs), which allow people with severe motor impairments such as paralysis or…

Electroencephalography(also: EEG)

A non-invasive method of recording electrical activity in the brain using electrodes placed on the scalp. EEG is fundamental to most consumer and research brain-computer interfaces because it is relatively inexpensive, portable, and safe compared to invasive neural recording…

Electrolarynx(also: Artificial Larynx, Electronic Larynx)

A handheld, battery-powered device that produces voice for people who have lost their larynx. The device is held against the neck or cheek and generates vibrations that travel through the throat tissues into the oral cavity, where the user shapes the vibration into speech using…

Electrolarynx(also: Artificial Larynx, Electric Larynx, EL Device)

A handheld battery-powered device that produces mechanical vibrations to generate speech for people who have lost their larynx (voice box), typically due to laryngeal cancer surgery. The device is held against the neck or cheek, where it transmits vibrations through the tissue…

Electromagnetic Actuation(also: EM Actuation)

A method of producing physical movement using electromagnetic fields generated by electric coils. In accessibility contexts, electromagnetic actuation is used to move tactile elements — such as magnetic markers or braille pins — to create dynamic tactile displays and interfaces…

Electromagnetic Tracking(also: Magnetic Tracking, 6-DOF Tracking)

Electromagnetic tracking is a position and orientation sensing technology that uses electromagnetic fields to determine the location and rotation of a sensor in three-dimensional space. Systems like the Polhemus tracker generate a low-frequency magnetic field from a stationary…

Electromyography(also: EMG, Electromyogram)

Electromyography (EMG) is a technique for measuring the electrical activity produced by muscles when they contract or are at rest. In accessibility and assistive technology, EMG sensors placed on the skin can detect muscle activations even when there is no visible movement,…

Electronic Assistive Technology(also: EAT, Electronic AT)

Computer-based devices and systems that enable people with severe disabilities to perform tasks they would otherwise be unable to accomplish, including communication, environmental control, mobility, and computer access. Electronic assistive technologies are often integrated…

Electronic Curb-Cut Effect(also: Digital Curb-Cut Effect, Curb-Cut Effect)

The phenomenon where accessibility features originally designed for people with disabilities end up benefiting a much wider population. Named after physical curb cuts in sidewalks — originally mandated for wheelchair users but widely used by people with strollers, delivery…

Electronic Textbook(also: E-Textbook, Digital Textbook, Interactive Textbook)

A digital version of an educational textbook that goes beyond simply reproducing printed content on screen by offering interactive features such as searchable text, bookmarking, embedded exercises and assessments, multimedia content, annotations, progress tracking, and adaptive…

Electronic Travel Aid(also: ETA)

An electronic device designed to help blind or visually impaired people navigate their environment by detecting obstacles and conveying spatial information through non-visual feedback such as audio cues, vibrations, or tactile signals. Electronic travel aids range from simple…

Electrooculogram(also: EOG, Electrooculography)

The electrooculogram (EOG) is a technique for measuring the electrical potential difference between the front and back of the eye using surface electrodes placed around the eyes. This corneal-retinal potential (CRP) varies linearly with eye rotation along both horizontal and…