Glossary

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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…

Executive function(also: Executive functioning, Cognitive control)

A set of higher-order cognitive processes that enable goal-directed behaviour, including planning, working memory, attention control, task switching, inhibition of inappropriate responses, and flexible thinking. Executive function difficulties are common in TBI, ADHD, autism,…

Exercise Accessibility(also: Fitness Accessibility, Accessible Physical Activity)

The design of exercise environments, equipment, programs, and technologies to be usable by people with disabilities. Exercise accessibility encompasses both physical spaces (accessible gyms, adapted tracks, swimming pools with lifts) and the technologies and guidance systems…

Exergame(also: Exercise game, Active video game, Fitness game)

A video game that requires physical movement or exercise as the primary interaction mechanism, combining gameplay elements like scoring, levels, and achievements with physical activity. Accessible exergames for people with disabilities use alternative feedback modalities — such…

Exergame(also: Exercise Game, Active Video Game, Exergaming)

A video game that requires physical movement or exercise as the primary input mechanism, combining gameplay with physical activity. Exergames have been developed for consoles, virtual reality systems, and mobile devices, with applications in rehabilitation, fitness, and physical…

Exergame(also: Exercise Game, Exergaming, Active Video Game)

A video game that requires physical activity beyond traditional handheld controller manipulation, combining gaming with exercise. Exergames use motion sensors, cameras, balance boards, or other input devices to track body movements as game controls. In rehabilitation contexts,…

Exergames(also: Exertion games, Active video games, AVGs)

Video games designed to require physical exertion — whole-body movement, resistance, or sustained aerobic activity — as the primary input modality. Exergames span consumer titles (e.g., Wii Fit, Ring Fit Adventure) and clinical applications for rehabilitation, balance training,…

Exergaming(also: Exercise Gaming, Active Gaming, Exergames)

A category of digital games that require physical movement or exercise as the primary means of interaction, combining gameplay with physical activity. Exergames use motion sensors, pressure pads, cameras, cycling devices, or other physical interfaces to translate body movements…

Exif(also: Exchangeable Image File Format, EXIF)

A standard metadata format embedded within image files (JPEG, TIFF, and others) that stores information about how an image was created, including camera model, date, GPS coordinates, and orientation. Exif data travels with the image file through most sharing and editing…

Existential OCD

A non-standardized but clinically recognized subtype of Obsessive-Compulsive Disorder (OCD) characterized by obsessions about the nature of reality, consciousness, free will, mortality, or the fate of humanity. In the GenAI era, existential OCD commonly presents as intrusive…

Exoskeleton(also: Robotic Exoskeleton, Wearable Exoskeleton)

A wearable mechanical or robotic device that fits around a part of the body — typically the hand, arm, or leg — and provides powered movement assistance, resistance, or guided motion. In rehabilitation contexts, exoskeletons are used to support intensive, repetitive motor…

Expanded Core Curriculum(also: ECC)

A specialized curriculum for blind or visually impaired (BVI) students that supplements traditional academics with skills that sighted students typically learn through observation. The ECC covers nine areas of instruction: compensatory skills, sensory efficiency, orientation and…

Experience Sampling Method(also: ESM, Ecological Momentary Assessment, EMA)

A research methodology that collects data about participants' experiences, behaviors, and states in real time and in natural settings through repeated brief surveys or prompts delivered at predetermined or random intervals throughout the day. In accessibility research, ESM…

Experience sampling method(also: ESM, Ecological momentary assessment, EMA)

A research methodology that captures participants' experiences, behaviours, and psychological states in real time as they go about their daily lives, typically through repeated brief surveys triggered at random intervals or after specific events. ESM reduces recall bias compared…

Experience-Based Co-Design(also: EBCD)

A participatory methodology originally developed in UK health services research that treats people's lived experience - their 'emotional touch-points' of confusion, frustration, or insight - as the core material for designing services or systems. Canonical EBCD stages include…

Experiential Accessibility(also: Experience-Centric Accessibility)

An approach to accessibility that goes beyond removing barriers to ensure disabled people can have equitable, meaningful experiences with technology—not just functional access. In the context of experiential technologies like virtual reality or games, this means designing for…

Experiential Layer Accessibility

The dimension of VR accessibility concerned with the quality, comfort, and safety of the VR experience for disabled users. This includes physical comfort (avoiding pain, exhaustion, and motion sickness), safety (preventing real-world collisions, addressing harassment in…

Experiential Learning Theory(also: ELT)

An educational theory emphasizing the value of hands-on experiences and reflection in learning. Developed by David Kolb, it posits that effective learning occurs through a cycle of concrete experience, reflective observation, abstract conceptualization, and active…

Experiential Transcoding

An approach to web page transcoding that restructures content based on actual user behaviour rather than relying solely on source code analysis or predefined heuristics. By analysing how sighted users interact with web pages — typically through eye-tracking data — experiential…