Glossary

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Entity Density(also: Entity-Density Features)

A discourse-level readability feature measuring how many distinct entities — named entities (people, places, organisations) and general nouns — a text introduces per sentence or document. High entity density increases working-memory load on readers because each new entity must…

Entity Grid(also: Entity-Grid Model)

A model of local text coherence proposed by Barzilay and Lapata (2008) that represents a document as a two-dimensional grid: rows are sentences, columns are salient entities, and each cell records the grammatical role of that entity in that sentence (subject, object, other, or…

Entity-Relationship Diagram(also: ER Diagram, ERD)

A type of relational diagram used in software engineering and database design to model the conceptual structure of a system by representing entities (objects or concepts), their attributes (properties), and the relationships between them. ER diagrams are widely used by system…

Environmental Awareness(also: Situational Awareness, Environmental Sound Awareness)

The perception and understanding of what is happening in one's physical surroundings, particularly through auditory cues. For Deaf and hard of hearing individuals, environmental awareness is often reduced because many everyday signals — appliance timers, doorbells, approaching…

Environmental Control(also: Environmental Control Unit, ECU, Smart Home Control)

Technology that enables people with severe physical disabilities to independently control aspects of their environment such as lights, doors, temperature, televisions, phones, and other electronic devices. Environmental control systems can be operated through various access…

Environmental Control System(also: ECS, Electronic Aids to Daily Living, EADL)

An environmental control system (ECS) is an assistive technology that enables people with physical disabilities to independently control devices and features in their environment, such as lights, doors, televisions, phones, and computers. ECS devices accept input through various…

Environmental Flow(also: Optic Flow, Sensory Flow)

The ordered changes in a pedestrian's distances and directions to surrounding objects that occur while walking, providing continuous feedback about spatial position and movement through the environment. For sighted people, environmental flow is primarily visual (optic flow), but…

Environmental Legibility(also: Legibility of the Environment, Spatial Legibility)

The ease with which people can perceive, understand, and form mental maps of a physical environment in order to orient themselves and navigate through it. Coined by urban planner Kevin Lynch, legibility refers to the visual clarity of a cityscape or built environment — how…

Environmental Sound(also: Ambient Sound, Non-Speech Audio)

Any auditory information in a person's surroundings that is not speech, including sounds from appliances, alarms, animals, doorbells, traffic, weather, and other environmental sources. For deaf and hard of hearing people, awareness of environmental sounds is a significant…

Envision AI(also: Envision)

An AI-powered visual assistance technology available as a smartphone app and as smart glasses that provides scene descriptions, text reading, and object identification for blind and low vision users. Envision uses computer vision and large language models to describe visual…

Epilepsy(also: Seizure Disorder)

A chronic neurological condition characterized by recurrent, unprovoked seizures caused by abnormal electrical activity in the brain. Epilepsy affects roughly 1% of the population globally and spans a wide range of seizure types and severities, with some people experiencing…

Episodic Disability

A disability characterized by periods of illness or impairment interspersed with periods of wellness or relative health. Unlike fluctuating disability where severity varies continuously, episodic disability involves distinct episodes that may be unpredictable in timing,…

Episodic Memory(also: Autobiographical Memory, Personal Experience Memory)

The memory of specific personal experiences and events, including details about what happened, where and when it occurred, and the emotions associated with it. Episodic memory allows people to mentally "travel back in time" to re-experience past events from a first-person…

Episodic Productivity(also: Nonlinear Productivity, Burst Productivity)

A work pattern characterized by fluctuating cycles of high and low engagement rather than consistent, steady output. Common among people with ADHD and other neurodivergent conditions, episodic productivity involves periods of intense focus and high output alternating with…

Epistemic Barrier(also: Knowledge Barrier, Epistemic Divide)

A barrier to collaboration or understanding that arises from fundamental differences in knowledge systems, expertise, values, and ways of knowing between groups. In the context of sign language AI development, epistemic barriers exist between machine learning practitioners (who…

Epistemic Contingency

A concept from disability studies scholar Rod Michalko describing the start of acquiring a visual disability as an ongoing negotiation of ways of knowing. Blind epistemology — ways of knowing as a blind person — is fluid and relational, shaped by objects, environments, memories,…

Epistemic Injustice(also: Knowledge Injustice)

A form of injustice that occurs when someone is wronged in their capacity as a knower — either by having their testimony dismissed or undervalued (testimonial injustice) or by lacking the conceptual resources to understand their own experience (hermeneutical injustice). In…

Epistemic Violence(also: Epistemic Injustice)

The systematic marginalization, dismissal, or overriding of certain groups' knowledge, experiences, and ways of understanding the world. In disability contexts, epistemic violence occurs when non-disabled researchers, clinicians, or companies claim authority over disabled…

Equal Error Rate(also: EER, Crossover Error Rate)

A metric used to evaluate biometric system performance, representing the point at which the false acceptance rate (wrongly accepting unauthorized users) equals the false rejection rate (wrongly rejecting authorized users). Lower EER values indicate better system accuracy. In…

Equaliser(also: EQ, Equalizer)

An audio processing tool used in music production and sound engineering that adjusts the frequency content of an audio signal by boosting or cutting specific frequency ranges. Equalisers are controlled through parameters including frequency centre (which frequency to adjust),…

Equality Act(also: Equality Act 2010, UK Equality Act)

UK legislation that consolidates and strengthens anti-discrimination law across nine protected characteristics including disability. The Act prohibits direct and indirect discrimination in services, public functions, premises, work, education, and associations. For disability…

Equalization(also: EQ, Audio Equalization, Adaptive Equalization)

The process of adjusting the balance of frequency components in an audio signal by boosting or attenuating specific frequency bands. In accessibility contexts, adaptive equalization can be used to compensate for background noise by selectively boosting frequencies that are being…

Ergonomic Keyboard(also: Ergonomic Input Device)

A keyboard designed to reduce physical stress, strain, and injury risk during typing by conforming to the natural posture and biomechanics of the hands, wrists, and arms. Ergonomic keyboard designs include split keyboards (angled halves to reduce ulnar deviation), tented…

Ergonomics(also: Human factors engineering)

The scientific discipline concerned with understanding interactions between humans and other elements of a system, and the profession that applies theory, principles, data, and methods to design in order to optimize human well-being and overall system performance (IEA…

Error Profile(also: Accessibility Error Profile, Violation Profile)

An error profile is a structured summary of the accessibility issues detected on a page, typically represented as a numeric vector with one component per checkpoint or rule — counts of violations, binary pass/fail indicators, or failure rates. Error profiles were introduced in…

Error Recovery(also: Error Correction, Error Handling)

The process and mechanisms by which users can identify, understand, and correct errors that occur during interaction with a system. In accessibility contexts, error recovery is particularly important because errors can be harder to detect with assistive technologies—a screen…

Error Taxonomy(also: Error Classification, Error Typology)

A systematic classification of the types of errors that users or learners commonly make, organised into categories based on the nature, source, or linguistic level of the error. In accessibility and educational technology, error taxonomies are used to build intelligent systems…

Error Tolerance(also: Error Prevention, Forgiveness)

A design principle requiring that systems anticipate, prevent, and gracefully handle user errors. In accessible design, error tolerance means providing clear validation messages, allowing users to undo actions, confirming destructive operations, and ensuring that mistakes do not…

Error correction strategy(also: Text correction, Input error recovery)

The methods and behaviours users employ to detect and fix errors during text input, including backspace deletion, cursor repositioning, autocorrect, and retyping. For blind and visually impaired users, error correction is disproportionately costly because detecting errors…

Error-spread modelling(also: Error propagation modelling, Error radiation)

An approach to evaluating the impact of speech recognition errors that accounts for how a single misrecognized word degrades comprehension of its neighbouring words, not just the word itself. For example, misrecognizing "kitchen" as "kitten" makes the subsequent word "area"…

Errorless Learning(also: Errorless Teaching, Error-Free Learning)

Errorless learning is a teaching methodology that structures tasks so that learners are guided toward correct responses and prevented from making mistakes during the learning process. In accessible technology design, this translates to systems that do not allow incorrect actions…

Escapism

The use of entertainment, fantasy, or immersive experiences to temporarily disconnect from real-world concerns, limitations, or stressors. In VR accessibility research, escapism is a significant motivator for disabled users, who may value VR as an opportunity to experience…

Esports(also: Competitive Gaming, Electronic Sports, E-Sports)

Organised, competitive video-game play — typically involving tournaments, teams, audiences, and professional players. Esports has grown into a major global industry and a site of accessibility research, because conventional game controllers and high-speed inputs can exclude…

Essential Tremor(also: ET, Benign Essential Tremor)

Essential tremor is one of the most common movement disorders, characterized by involuntary, rhythmic shaking that typically affects the hands and arms but can also involve the head, voice, and other body parts. Unlike Parkinson's disease tremor, essential tremor usually occurs…

Ethic of Care(also: Care Ethics, Feminist Ethics of Care)

A moral and methodological framework, rooted in feminist philosophy, that centers relationships, responsibility, and responsiveness to the needs of others rather than abstract principles or transactional exchange. In accessibility and participatory research, an ethic of care…

Ethics Washing(also: Ethics-Washing)

The practice of creating the illusion of high ethical standards through superficial transparency efforts, ethics committees, or principles documentation while actual practices do not reflect these stated values. In technology contexts, ethics washing may involve publishing AI…

Ethnographic Study(also: Ethnography, Ethnographic Research)

A qualitative research methodology originating in anthropology that involves prolonged, immersive observation of people in their natural environments to understand their behaviours, practices, and social contexts. In accessibility and assistive technology research, ethnographic…

Ethnography(also: Ethnographic Research, Ethnographic Methods)

A qualitative research methodology originating in anthropology that involves observing people in their natural environments to understand their behaviours, practices, and social interactions in context. In accessibility research, ethnographic methods such as participant…

Ethnomethodology

A sociological approach, founded by Harold Garfinkel, that studies the everyday methods people use to make sense of and produce social order in interaction - the implicit rules and shared practices through which we treat ordinary situations as ordinary. Conversation analysis…

European Accessibility Act(also: EAA, Directive 2019/882)

A European Union directive adopted in 2019 that establishes common accessibility requirements for key products and services across EU member states. The EAA covers computers, smartphones, ATMs, e-commerce, banking services, e-books, and electronic communications, among others.…

Evaluation Reliability(also: Inter-rater Reliability, Evaluator Agreement)

The extent to which independent accessibility evaluations of the same content produce consistent results. High reliability means that different evaluators using the same method will identify similar sets of accessibility problems, while low reliability indicates that results…

Evaluator Effect

The evaluator effect refers to the phenomenon where different accessibility evaluators identify different sets of problems when assessing the same website, leading to variability in evaluation results. This effect has been documented in both expert reviews and user testing,…

Evaluator Effect

The phenomenon in accessibility and usability evaluation where different evaluators examining the same interface detect different sets of problems and may reach different conclusions about the same issues. The evaluator effect means that no single evaluation can achieve 100%…

Event-Related Potential(also: ERP)

An event-related potential (ERP) is a measured brain response that is the direct result of a specific sensory, cognitive, or motor event. ERPs are extracted from electroencephalography (EEG) recordings by averaging brain signals time-locked to repeated presentations of a…

Evocation(also: Word Association Strength, Semantic Evocation)

A measure of how strongly one word brings another word to mind, reflecting the associative connections between concepts in human semantic memory. Unlike formal semantic relationships such as synonymy or hyponymy, evocation captures the informal, often idiosyncratic associations…

Exam Accommodation(also: Test Accommodation, Assessment Accommodation)

Modifications to examination conditions that enable students with disabilities to demonstrate their knowledge and abilities on an equal basis. Exam accommodations for students with vision impairments include extra time, Braille question papers, use of scribes, screen reader…

Execution Gap(also: Gulf of Execution)

From Don Norman's model of human-computer interaction, the distance between a user's goals and the physical actions required to achieve them using a given system. A system with a wide execution gap forces users to translate what they want into technical commands, parameters, or…

Executive Dysfunction(also: Executive Function Deficit, EF Impairment)

A disruption in the efficiency of executive functions that affects a person's ability to plan, organize, initiate tasks, manage time, make decisions, and regulate behavior. Executive dysfunction is a core feature of ADHD and is also associated with autism, depression, traumatic…

Executive Function(also: EF, Executive Functioning)

A set of higher-order cognitive processes that enable planning, organizing, initiating tasks, sustaining attention, managing time, regulating emotions, and adapting to new situations. Executive functions are critical for goal-directed behavior and are commonly impaired in…

Executive Function(also: Executive Functioning, Cognitive Control, Executive Control)

A set of cognitive processes that enable goal-directed behavior, including planning, working memory, attention, inhibitory control, and cognitive flexibility. Executive functions allow individuals to organize, initiate, and monitor tasks in daily living. In accessibility…