Glossary

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BATE Principle(also: Beyond Accessibility to Efficiency)

A design principle for assistive technology stating that devices should not merely provide basic access to a task but should enable a person with a disability to perform that task with the same efficiency as a non-disabled person. Coined in the iCARE Reader project at Arizona…

BBC Mobile Accessibility Guidelines(also: BBC MAG)

A comprehensive set of accessibility standards developed by the BBC for mobile application and web content design. The guidelines cover areas including design, editorial, code, and testing, with specific recommendations for touch targets, text sizing, color contrast, and…

BERT(also: Bidirectional Encoder Representations from Transformers)

A natural language processing model developed by Google that uses bidirectional training to understand context from both directions in a sentence. BERT and its variants like SBERT (Sentence-BERT) are increasingly used in accessibility applications for tasks such as automatic…

BETSIE(also: BBC Education Text to Speech Internet Enhancer)

BETSIE (BBC Education Text to Speech Internet Enhancer) was an early web accessibility tool developed by the BBC as a CGI Perl script that produced text-only versions of web pages optimized for users of text-to-speech systems. BETSIE handled frames by serializing them,…

BIGmack Switch(also: BIGmack, BIGmack Communicator)

A single-message assistive technology device that allows a user to press a large button to play a pre-recorded message. BIGmack Switches are widely used in special education and communication interventions for individuals with significant speech and motor disabilities, including…

BITV(also: Barrierefreie Informationstechnik-Verordnung, Barrier-Free Information Technology Regulation)

BITV (Barrierefreie Informationstechnik-Verordnung) is the German federal regulation on accessible information technology, mandating that federal government websites and applications be accessible to people with disabilities. First introduced in 2002 and updated as BITV 2.0 in…

BLE Beacon(also: Bluetooth Low Energy Beacon, iBeacon, Bluetooth Beacon)

A BLE (Bluetooth Low Energy) beacon is a small wireless transmitter that broadcasts a signal at regular intervals, which can be detected by nearby smartphones to determine a user's indoor location. In accessibility contexts, networks of BLE beacons are widely used to enable…

BLEU Score(also: BiLingual Evaluation Understudy, BLEU)

A metric for evaluating the quality of machine-generated text by comparing it to one or more reference (human-written) translations. BLEU calculates precision by counting how many n-grams (sequences of words) in the predicted text match n-grams in the reference text, with BLEU-1…

BLV(also: Blind and Low Vision, B/LV)

Abbreviation for "blind and low vision," an umbrella term referring to people with a range of visual conditions including total blindness, legal blindness, and various forms of low vision. The term is widely used in accessibility research and practice to describe the user…

BLV Users(also: Blind and Low Vision Users, BLV People)

People who are blind or have low vision, encompassing a spectrum of visual impairments from total blindness to varying degrees of remaining vision (light perception, tunnel vision, blurred vision, etc.). BLV users are a primary user group for many accessibility technologies…

BS 8878(also: British Standard 8878, Web Accessibility Code of Practice)

A British Standard published in 2010 that provides a code of practice for web accessibility. BS 8878 defines a 16-step process for implementing web accessibility within organisations, taking a user-centred approach that goes beyond technical conformance with WCAG. It emphasises…

BVI(also: Blind and Visually Impaired, BLV, Blind and Low Vision)

A widely used abbreviation in accessibility and HCI research denoting "blind and visually impaired" — the inclusive category that covers people who are totally blind, legally blind, or have any form of low vision. Closely related variants include BLV ("blind and low vision"),…

Babbling(also: Canonical Babbling, Prelinguistic Vocalization)

The repetitive, syllable-like vocalizations produced by infants typically between 6 and 12 months of age as a precursor to spoken language. Babbling progresses through developmental stages from simple vowel-like sounds (cooing) to reduplicated sequences like "bababa" and…

Back Tap(also: Back Tap Gesture)

An iOS accessibility feature that allows users to trigger actions by tapping on the back of their iPhone two or three times. Back Tap can be configured to activate shortcuts, accessibility features, or system functions without requiring precise touchscreen interaction. For…

Back-Translation(also: Reverse Translation)

A quality assurance method used in survey and instrument translation where a translated version is independently translated back into the original language by a different translator. The back-translated text is then compared with the original to identify meaning losses or…

Back-end Development(also: Server-side Development, Back-end Engineering)

The practice of building server-side logic, databases, APIs, and application architecture that power websites and applications. Back-end developers work with languages like Python, Java, Ruby, and Node.js, focusing on data processing, authentication, and business logic rather…

Back-translation(also: Reverse translation)

A validation technique in cross-linguistic instrument translation where an independently translated version (e.g., ASL video) is translated back into the source language (e.g., English) by someone who did not see the original, then compared for meaning equivalence.…

Backchannel Feedback(also: Backchannel, Backchanneling, Backchannel Cues)

Verbal or non-verbal signals given by a listener during a conversation to show attention, understanding, or agreement without taking over the speaking turn. Common examples include head nods, vocalizations like mm-hmm, thumbs-up gestures, and brief verbal affirmations.…

Backchanneling(also: Backchannel, Listener Feedback, Active Listening Signals)

The verbal and non-verbal signals that listeners produce during conversation to indicate engagement, understanding, agreement, or encouragement without taking a full speaking turn. Backchanneling includes utterances like "uh-huh," "mm-hmm," "yeah," and "right," as well as…

Background Blur(also: Depth of Field Effect, Bokeh Effect)

A visual technique that applies a blur filter to the background of a video while keeping foreground subjects in sharp focus, similar to a shallow depth-of-field camera effect. In accessibility contexts, background blur reduces visual distractions from busy or moving backgrounds…

Background Color Music(also: BCM)

A sonification technique that maps the background colors of visually distinct content regions on a web page to recognizable melodies, allowing blind users to perceive the color-based grouping structure of a page through hearing. Each background color is assigned a unique melody…

Background Mode

A privacy technique in visual assistance technologies that obfuscates a specific private object while preserving all other elements in the image or video. For example, a user might select a pill bottle as private content, and background mode would blur or hide only the pill…

Background Music(also: BGM, Underscore)

Continuous music that plays beneath narration or dialogue to establish mood, atmosphere, and emotional tone in media. In accessible audio production, background music should be distinguished from discrete sound effects: BGM sustains ambience and should continue underneath audio…

Background Noise(also: Ambient noise, Environmental noise)

The sum of unwanted or competing sound in an environment — traffic, construction, conversation, HVAC systems, weather — that is present alongside a signal of interest. Background noise is characterized by sound level (dB), spectral content, duration, and steadiness versus…

Background Script(also: Background Scripts, Background Page)

Code in a browser extension that runs independently of any specific web page, handling long-lived logic such as responding to browser events, managing storage, or coordinating with remote services. Under Manifest V3, background scripts are implemented as service workers rather…

Background Subtraction(also: Foreground-Background Separation, Background Modelling)

Background subtraction is a computer vision technique used to identify moving objects (the foreground) in a video by comparing each frame against a model of the static background. Common approaches include adaptive Gaussian mixture models that continuously update the background…

Ballot Design(also: Accessible Ballot Design)

The layout and interaction design of the form through which voters select and cast their choices, covering paper ballots, electronic voting machines, and online interfaces. Well-studied accessibility and usability principles for ballot design include randomising the order of…

Ballot Marking Device(also: BMD, Ballot Marking System)

A ballot marking device (BMD) is an electronic system that assists voters in marking their ballot selections, typically producing a printed paper ballot as a verifiable record. Unlike direct recording electronic (DRE) voting machines that store votes digitally, BMDs produce a…

Bangla Sign Language(also: BdSL, Bangladeshi Sign Language)

The sign language used by the d/Deaf and hard-of-hearing community in Bangladesh. BdSL has distinct grammatical structures, vocabulary, and regional variation that differ from American Sign Language (ASL) and from the sign languages used in neighbouring countries. As a…

Barcode(also: Bar Code, QR Code, 1D Barcode)

A barcode is a machine-readable visual encoding of data — linear (one-dimensional, such as UPC or EAN) or matrix (two-dimensional, such as QR or DataMatrix codes). In a digital accessibility context, barcodes are commonly used as a lightweight way to attach identifying or…

Barrage Test(also: Cancellation Test, Visual Search Test)

A standardized neuropsychological assessment that measures selective and sustained visual attention by requiring participants to identify and mark target items among distractors on a page. Barrage tests vary in visual complexity, with more complex versions testing the ability to…

Barrier Impact Factor(also: BIF, Accessibility Barrier Impact)

A metric for measuring the severity of web accessibility barriers by weighting detected errors according to which assistive technologies and disability groups they affect. The BIF is calculated by summing the product of the number of errors and a weight value for each affected…

Barrier Pointing(also: Edge-Based Pointing)

An interaction technique for touch screens that uses the physical edges of a device as barriers to assist with target acquisition. When a target is placed near a screen edge, users can slide their finger or stylus toward the edge, using it as a physical stop to improve selection…

Barrier Walkthrough(also: BW Method)

The Barrier Walkthrough is a structured expert evaluation method for assessing web accessibility in which evaluators systematically examine a website against a predefined set of accessibility barriers rather than individual guideline success criteria. Unlike conformance-based…

Barrier Walkthrough(also: Structured Walkthrough)

A systematic accessibility evaluation method that guides evaluators through the process of identifying barriers that people with disabilities may encounter on a website. Unlike a standard conformance review that checks against all WCAG success criteria, a barrier walkthrough…

Barrier Walkthrough Method(also: BW Method, Barrier Walkthrough)

An accessibility evaluation method developed by Giorgio Brajnik that groups Web Content Accessibility Guidelines (WCAG) success criteria by user categories such as blind users, people with low vision, and motor-impaired users. Unlike standard WCAG audits that evaluate all…

Barrier-Free Housing(also: Accessible Housing, Barrierefrei)

Housing designed or modified to be usable by people with disabilities, typically addressing physical access features such as step-free entry, wide doorways, accessible bathrooms, and adjustable fixtures. In practice, barrier-free housing standards and filters on…

Bayesian Network(also: Bayes Network, Belief Network, Probabilistic Graphical Model)

A statistical model that represents probabilistic relationships among variables using a directed graph structure. In accessibility and assistive technology applications, Bayesian networks are used for behavior recognition—inferring what action a user is performing based on…

Be My AI

An AI-powered feature within the Be My Eyes app that uses GPT-4o to provide on-demand image descriptions for blind and low vision users. Users can take a photo or upload an image and receive a detailed AI-generated description, replacing the need to connect with a sighted…

Be My Eyes

A mobile application that connects blind and low-vision users with sighted volunteers or AI-powered visual assistance for help with visual tasks. Originally launched in 2015 as a crowdsourced human-to-human video call service, Be My Eyes has since integrated AI features ("Be My…

Beauty Accessibility(also: Accessible Beauty, Inclusive Beauty)

The design and practice of making beauty and personal grooming products, tools, services, and information accessible to people with disabilities. Beauty accessibility encompasses tactile and braille product labeling, non-visual makeup application techniques, accessible beauty…

Becker Muscular Dystrophy(also: BMD)

A genetic neuromuscular disorder caused by mutations in the dystrophin gene on the X chromosome, resulting in progressive muscle weakness and wasting. Becker Muscular Dystrophy is similar to Duchenne Muscular Dystrophy but generally has a later onset (typically in the teens or…

Beep Baseball(also: Beepball)

An adapted version of baseball designed for players who are blind or visually impaired. The game uses an oversized softball containing electronic beepers that emit sound, and bases that buzz when activated to indicate the target. Batters attempt to hit the beeping ball and run…

Beepball(also: Beep Baseball, Blind Baseball)

An adaptive version of baseball designed for players who are blind or visually impaired. The game uses a softball modified with a sound sensor that emits a beeping sound, and bases that buzz when activated, allowing players to locate the ball and bases through auditory cues. All…

Before-After Comparison(also: Before and After Feedback, Edit Comparison)

A feedback mechanism that describes the differences between an image or content before and after an edit has been applied, helping users understand the impact of their changes. For blind users editing visual content, before-after comparisons are essential because they cannot…

Behavior Change(also: Behavior Modification, Behavioral Intervention)

Behavior change refers to the systematic process of modifying specific behaviors through structured intervention techniques. In accessibility and disability contexts, behavior change strategies are used to help individuals develop adaptive behaviors, reduce challenging…

Behavior Rehearsal(also: Behavioral Rehearsal)

Behavior rehearsal is a structured practice technique, introduced by Brownsmith in behavioural psychology and widely used in social-skills training, in which a learner repeatedly practises a target behaviour in simulated scenarios with teacher or therapist guidance and feedback…

Behavioral Intervention(also: Behavior Intervention, Applied Behavior Analysis, ABA)

A systematic approach to understanding and modifying behavior, most commonly applied to support children with autism, ADHD, and other neurodevelopmental conditions. Behavioral intervention uses evidence-based techniques including prompting, reinforcement, cueing, and feedback…

Behaviour-Driven Development(also: BDD, Behavior-Driven Development)

A software development methodology that extends Test-Driven Development by writing test cases as human-readable scenarios in natural language, describing expected system behaviour from the user's perspective. BDD test scenarios typically follow a Given-When-Then format that…

Behavioural and Psychological Symptoms of Dementia(also: BPSD, Behavioural Disturbance, Neuropsychiatric Symptoms)

A range of non-cognitive symptoms and behaviours associated with dementia, including agitation, aggression, wandering, repetitive behaviours, sleep disturbances, anxiety, depression, delusions, and hallucinations. BPSD affects up to 90% of people with dementia at some point…