Glossary

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N-back Task(also: N-back, 2-back Task)

A working-memory paradigm in which participants view or hear a sequence of stimuli (letters, digits, positions) and, on each trial, respond when the current stimulus matches the one presented N steps earlier. Higher N levels place greater load on working memory and executive…

N-gram(also: Bigram, Trigram, Unigram)

A contiguous sequence of n items (typically words) from a text, used in language modeling to predict the probability of a word based on its predecessors. A unigram considers single words in isolation, a bigram considers pairs of consecutive words, and a trigram considers…

NASA Task Load Index(also: NASA-TLX, Task Load Index)

A widely used subjective workload assessment tool developed by NASA that measures perceived workload across six dimensions: mental demand, physical demand, temporal demand, performance, effort, and frustration. Participants rate each dimension on a scale, providing a…

NASA Task Load Index(also: NASA-TLX, TLX)

A widely used subjective workload assessment tool developed by NASA that measures perceived workload across six dimensions: mental demand, physical demand, temporal demand, performance, effort, and frustration. In accessibility research, NASA-TLX is frequently employed to…

NASA-TLX(also: NASA Task Load Index, Task Load Index, NASA TLX)

A widely used subjective workload assessment tool developed by NASA that measures perceived workload across six dimensions: mental demand, physical demand, temporal demand, performance, effort, and frustration. In accessibility research, NASA-TLX is frequently used to evaluate…

NCAM(also: National Center for Accessible Media)

A research and development facility at WGBH (Boston public media) that develops accessible media technologies and guidelines. NCAM created widely-adopted guidelines for describing STEM images (charts, graphs, diagrams) for people with visual impairments, developed through expert…

NDIS(also: National Disability Insurance Scheme)

Australia's national scheme for funding disability support services, established in 2013. The NDIS provides individualized funding packages to eligible Australians with permanent and significant disabilities, allowing them to choose and pay for support services that help them…

NER Model(also: Number, Edition, Recognition Model, NER Accuracy Model)

A caption-quality evaluation model developed by Pablo Romero-Fresco and Juan Martínez Pérez for measuring the accuracy of live subtitling and respeaking. Unlike Word Error Rate, which penalises all errors equally, the NER model weights each error by how much it affects the…

NFC(also: Near Field Communication)

A short-range wireless communication technology that enables data exchange between devices held within a few centimetres of each other. NFC is built into most modern smartphones and can read passive NFC tags embedded in objects. In accessibility applications, NFC tags can be…

NFC Tag(also: Near Field Communication Tag, NFC)

An NFC (Near Field Communication) tag is a small, unpowered chip that can transmit data to a compatible smartphone or device when held within a few centimeters. In accessibility contexts, NFC tags are used in museums, galleries, and public spaces to provide on-demand information…

NFC accessibility(also: NFC tags for accessibility)

The use of Near Field Communication (NFC) technology to make physical objects, materials, and environments accessible to people with disabilities. NFC tags can be embedded in physical cards, objects, or locations and triggered by tapping a smartphone or dedicated reader to…

NGO Intervention(also: Non-Governmental Organization Intervention, Civil Society Intervention)

Programs and initiatives led by non-governmental organizations to address gaps in public services, including education, healthcare, and assistive technology provision for people with disabilities. In India, NGOs like Vision Empower and Winvinaya Foundation have become critical…

NGOMSL(also: Natural GOMS Language)

A structured notation for writing GOMS (Goals, Operators, Methods, Selection rules) models in a program-like form that is readable by humans. NGOMSL was developed by David Kieras as a more formal variant of GOMS that includes selection rules and allows operators at the keystroke…

NIDILRR(also: NIDRR, National Institute on Disability, Independent Living, and Rehabilitation Research)

A U.S. federal agency within the Administration for Community Living that funds disability and rehabilitation research, including accessible technology development. Originally named NIDRR (National Institute on Disability and Rehabilitation Research), it was renamed NIDILRR in…

NIMAS(also: National Instructional Materials Accessibility Standard)

A technical standard in the United States that defines a consistent file format for producing accessible versions of print instructional materials. NIMAS is based on the DAISY/NISO standard and specifies how publishers must provide source files so they can be converted into…

NVDA(also: NonVisual Desktop Access)

A free, open-source screen reader for Windows developed by NV Access. NVDA provides speech and braille output, enabling blind and low-vision users to interact with the operating system, web browsers, and applications. Since its release in 2006, NVDA has become one of the most…

NVDA(also: NonVisual Desktop Access)

A free, open-source screen reader for Microsoft Windows developed by NV Access. NVDA enables people who are blind or have low vision to use computers by reading on-screen text aloud through a speech synthesizer or outputting to a refreshable Braille display. As open-source…

Named Entity Recognition(also: NER)

A natural language processing technique that identifies and classifies named entities in text into predefined categories such as person names, locations, organizations, quantities, and domain-specific terms. In accessibility applications, NER can be used to extract meaningful…

Naming Practice(also: Confrontation Naming, Naming Therapy, Picture Naming)

A speech-language therapy technique in which individuals with aphasia are shown pictures of familiar objects and asked to produce the corresponding word. Naming practice is one of the most common and well-evidenced interventions for word finding difficulties (anomia) in people…

Narrative Engagement(also: Story Engagement)

A multidimensional construct used in media studies and HCI research to capture how deeply a viewer is drawn into a story, including narrative understanding, attentional focus, narrative presence (the feeling of being inside the story world), and emotional engagement with…

Narrative Immersion(also: Story Immersion, Narrative Presence)

A psychological state in which the audience becomes deeply absorbed in a story world, perceiving the mediated content as if it were an unmediated reality. In accessible media, narrative immersion encompasses spatial presence (feeling present in the story environment), content…

Narrative Prosthesis

A concept from disability studies describing how disability is used as a literary and rhetorical device—a plot driver, metaphor, or character-enriching detail—within narratives that ultimately serve the interests and perspectives of non-disabled people rather than accurately…

Narrative Route Description(also: Verbal Route Guidance, Turn-by-Turn Narrative)

A structured verbal representation of a travel route that guides users through sequential steps using spoken or text-based instructions. Effective narrative descriptions for blind travelers typically follow a consistent format: action to take, distance information, then landmark…

Narrative Skills(also: Narrative Competence, Storytelling Skills)

The ability to recount events — real or imagined — as a coherent, temporally ordered, causally linked story that another person can follow. Narrative skills rest on autobiographical memory retrieval, event sequencing, referential clarity (introducing and tracking characters),…

Narrative Style(also: Descriptive Style, AD Voice)

The distinctive approach a describer takes when writing audio descriptions, encompassing choices about language formality, emotional tone, level of interpretation, detail density, and pacing. Narrative style in audio description ranges from strictly objective and impersonal to…

Narrative-Flip Method(also: Narrative flip)

A qualitative HCI research method in which participants first encounter a technology or artifact without knowing its origins or intent, reflect on it, and only afterwards are told its disability-led, activist, or political context. The deliberate before/after framing surfaces…

Narrator(also: Windows Narrator)

The built-in screen reader included with Microsoft Windows operating systems. Narrator reads aloud text on screen, describes notifications and interface elements, and allows users to navigate Windows and applications using keyboard commands. First introduced in Windows 2000 as a…

Narrow-Deep Interface(also: Narrow-Deep UI, Wizard Interface, Step-by-Step Interface)

A user interface design pattern that presents information across many screens, with only a small amount of content per screen. Users navigate through multiple sequential screens rather than scrolling through dense content. This approach reduces cognitive load by focusing…

Narrowband Audio(also: NB Audio, Standard Definition Voice)

Audio transmission limited to the frequency range of approximately 300-3,400 Hz, which has historically been the standard for telephone networks (PSTN). While sufficient for basic speech intelligibility, narrowband audio excludes higher frequency consonant sounds that aid speech…

National Accessibility Portal(also: NAP, South African National Accessibility Portal)

A South African government-supported web portal developed by the Meraka Institute (CSIR) to provide accessible information sharing for the disability sector. The NAP was designed from inception as an accessible platform, featuring alternative CSS stylesheets for different font…

National Diet Library(also: NDL, NDL Japan)

The national library of Japan, founded in 1948, and a major stakeholder in the production of accessible Japanese digital content. NDL operates large-scale digitisation projects for historical and contemporary Japanese materials, partners with blind-readers' organisations and…

National Federation of the Blind(also: NFB)

The largest membership organization of blind people in the United States, founded in 1940. The NFB advocates for the rights and equality of blind and low vision people through policy work, technology advocacy, education, and community building. The organization frequently…

National Library Service(also: NLS, National Library Service for the Blind and Print Disabled)

A program of the Library of Congress in the United States that provides Braille and audio materials to eligible borrowers who are blind, have low vision, or have physical disabilities that prevent them from reading standard print. The NLS operates through a network of regional…

National Technical Institute for the Deaf(also: NTID)

The National Technical Institute for the Deaf (NTID), one of the nine colleges of Rochester Institute of Technology (RIT), is the first and largest technical college in the world for students who are deaf or hard of hearing. Established by U.S. federal legislation in 1965, NTID…

National Transition Strategy (NTS)(also: NTS, Web Accessibility National Transition Strategy)

The Australian Government's National Transition Strategy was a formal policy established in June 2010 requiring all federal, state, and territory government websites to conform to WCAG 2.0. It set staged milestones — Level A conformance by December 2012 and Level AA by December…

Native Signer(also: Native Sign Language User, L1 Signer)

A person who acquired a sign language as their first language (L1) during the critical period of language development, typically before age 5. Native signers usually learned sign language from deaf parents or through early immersion in deaf education environments. In…

Natural Language Command(also: Natural Language Input, Conversational Command)

A user input expressed in everyday spoken or written language rather than structured syntax or specific command formats. In accessibility contexts, natural language commands enable BLV users to interact with systems without memorizing precise command structures or navigating…

Natural Language Generation(also: NLG, Text Generation)

A subfield of artificial intelligence and computational linguistics focused on automatically producing human-readable text from structured data or other non-linguistic representations. In accessibility, natural language generation is used to create textual descriptions of visual…

Natural Language Interface(also: NLI, Natural Language User Interface)

A user interface that allows people to interact with technology using everyday language rather than specialized commands, menus, or graphical controls. Natural language interfaces can improve accessibility by reducing the learning curve for technology use, supporting users with…

Natural Language Processing(also: NLP, Computational Linguistics)

A branch of artificial intelligence that enables computers to understand, interpret, and generate human language. In accessibility, NLP powers voice-based assistive technologies, automatic captioning, text simplification for cognitive accessibility, and natural language query…

Natural Language Query(also: NLQ, Conversational Query, Natural Language Search)

An interaction paradigm where users pose questions or issue commands in everyday language rather than using structured search syntax, predefined filters, or navigation controls. In accessibility contexts, natural language querying is particularly valuable for screen reader users…

Natural Language Understanding(also: NLU, Intent Recognition, Language Understanding)

A branch of artificial intelligence that enables computers to interpret the meaning and intent behind human language input, rather than requiring exact predetermined phrases or commands. In accessibility contexts, NLU is valuable for voice-controlled interfaces because it allows…

Natural Speech Output(also: Recorded Speech, Digitized Speech)

Speech output produced from digital recordings of actual human speakers, as opposed to artificially generated synthetic speech. Natural speech output preserves the prosody, intonation, emotion, and vocal quality of the original speaker, making it generally more pleasant and…

Natural User Interface(also: NUI)

A user interface designed to feel intuitive and invisible, allowing users to interact with technology through natural behaviors such as gestures, voice, touch, or body movement rather than learned conventions like mouse clicks or keyboard commands. NUIs are particularly valuable…

Nature Engagement(also: Engagement with Nature)

The active, lived practice of spending time in and interacting with natural environments - walking in parks, gardening, listening to birdsong, touching plants, sitting by water, and similar embodied encounters. Nature engagement extends beyond physical presence to multisensory,…

Nature Relatedness(also: Nature Relatedness Scale, NRS, Nature Connectedness)

A psychological construct describing the strength of a person's affective, cognitive, and experiential connection to the natural world. It is most often measured with the 21-item Nature Relatedness Scale (NRS) developed by Nisbet, Zelenski, and Murphy, which yields three…

NavCog(also: Navigational Cognitive Assistant)

A Bluetooth beacon-based navigation system developed at Carnegie Mellon University that provides indoor turn-by-turn navigation assistance and environmental information to blind and visually impaired users via smartphone. NavCog works by detecting BLE (Bluetooth Low Energy)…

NavTap

A navigational text-entry method designed for blind mobile phone users that reduces the cognitive load associated with inputting text without visual feedback. NavTap organizes the alphabet into five rows beginning with vowels and allows users to navigate between letters using…

Navigability(also: Ease of Navigation, Web Navigability)

The ease and efficiency with which a user can move through a web page, application, or document to reach their intended content. For accessibility practice, navigability is a primary determinant of whether a screen-reader, voice-browser, or keyboard-only user can actually…

Navigation

The task of moving through an environment to reach a destination, encompassing route planning, mode selection, real-time decision-making, and responding to obstacles. In accessibility research, navigation is often paired with wayfinding (the embodied, situated practice of…