Glossary

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Neurodevelopmental Disorders(also: NDD, Neurodevelopmental Disabilities)

A group of conditions that originate during the developmental period and are characterized by impairments in personal, social, academic, or occupational functioning. Neurodevelopmental disorders include intellectual disability, autism spectrum disorder, ADHD, specific learning…

Neurodivergence(also: Neurodiversity, Neurodivergent)

The natural variation in human neurological development and functioning that includes conditions such as autism, ADHD, dyslexia, anxiety disorders, intellectual disabilities, and other neurological differences. The neurodiversity paradigm frames these differences as natural…

Neurodivergent(also: Neurodiverse Individual, ND)

A term describing individuals whose neurological development and functioning differ from what is considered typical or "neurotypical." Neurodivergent conditions include ADHD, autism spectrum disorder, dyslexia, dyscalculia, Tourette syndrome, and other neurological differences.…

Neurofeedback(also: EEG Biofeedback, Neurotherapy)

Neurofeedback is a type of biofeedback that uses real-time monitoring of brain electrical activity (typically via EEG) to teach individuals to self-regulate their brain function. Users receive feedback — often through visual, audio, or game-based interfaces — about their current…

Neuroinclusive Design(also: Neurodiverse Design, Neurodiversity-Affirming Design)

A design approach that explicitly accounts for the varied cognitive, sensory, and communication needs of neurodivergent individuals alongside neurotypical users. Neuroinclusive design goes beyond general accessibility by addressing specific patterns such as different information…

Neuronormativity(also: Neurotypical bias, Neuronormative standards)

The set of assumptions, norms, and practices that privilege neurotypical cognition as the default and superior way of thinking, communicating, and functioning, while treating neurodivergent ways of processing as deficient or deviant. Neuronormativity manifests in technology…

Neurotype

A classification of minds based on patterns of neurological functioning. The term encompasses both neurotypical (conforming to dominant neurological norms) and neurodivergent (diverging from those norms, including autism, ADHD, dyslexia, and other neurological variations).…

Neurotypical(also: NT)

A term used to describe individuals whose neurological development and cognitive functioning fall within the range considered typical by prevailing societal standards — that is, people who do not have autism, intellectual disabilities, learning disabilities, or other…

Neurotypical Norms(also: Neurotypical Standards, Normative Expectations)

Social, behavioural, and professional expectations that are based on neurotypical patterns of cognition, communication, and functioning, often embedded unconsciously in technology, workplace culture, and institutional practices. Examples include job postings requiring candidates…

Non-Visual Mental Model(also: Non-Visual Representation, Tactile Mental Model)

A cognitive representation of concepts, objects, or systems built through non-visual sensory channels — primarily touch, hearing, and proprioception — rather than through sight. People who are blind develop non-visual mental models that may differ structurally from visual models…

Nonverbal Learning Disorder(also: NVLD, Nonverbal Learning Disability, NLD)

A neurodevelopmental condition characterized by difficulties with visual-spatial processing, motor coordination, and social skills, while verbal abilities are typically a relative strength. People with NVLD may struggle with interpreting visual information, understanding spatial…

Normative Language(also: Normativity in Assessment)

Language in assessment tools, questionnaires, or descriptions that implicitly establishes neurotypical or non-disabled experience as the standard against which all responses are measured. In emotional dysregulation measures, normative language includes loaded adjectives like…

Notification Fatigue(also: Alert Fatigue, Information Overload)

Notification fatigue is a state in which users become desensitized to or overwhelmed by frequent alerts, notifications, or information delivery from a device or system, causing them to ignore or tune out important messages. In accessibility contexts, notification fatigue is a…

Number Sense(also: Numeracy Intuition, Numerical Cognition)

The intuitive understanding of numbers, their magnitude, relationships, and how they are affected by operations. Number sense includes the ability to estimate quantities, understand relative size, recognize patterns, and make meaningful comparisons between numbers without…

Numeracy(also: Mathematical Literacy, Quantitative Literacy)

The ability to understand, use, and reason with numbers and mathematical concepts in everyday contexts. Numeracy skills include counting, arithmetic operations, understanding percentages and proportions, interpreting number lines, and making sense of numerical information in…

On Input(also: WCAG 3.2.2)

WCAG 2.1 success criterion 3.2.2 (Level A) requires that changing the setting of any user interface component does not automatically cause a change of context (e.g., submitting a form, navigating to a new page, or moving focus to another component) unless the user has been…

On-Demand Simplification(also: On-demand text simplification, User-initiated simplification)

An interaction pattern for Automatic Text Simplification reading-assistance tools in which the user explicitly requests a simpler version of a word, phrase, or sentence — typically via hover, click, or tap — rather than having the system pre-apply simplifications to the page…

OpenDyslexic(also: Open Dyslexic)

A free, open-source typeface specifically designed to improve readability for people with dyslexia. The font uses heavier bottom portions on letters to help prevent visual rotation and uses unique letter shapes to reduce confusion between similar characters. However,…

Order-Irrelevance Principle

The counting principle that the order in which objects are counted does not affect the total — counting the same set of objects in any sequence will yield the same number. This concept, while intuitive for most people, is often not understood by learners with dyscalculia, who…

Orthographic Depth(also: Orthographic Transparency, Spelling Transparency)

The degree of consistency in the relationship between letters (graphemes) and sounds (phonemes) in a writing system. Languages with shallow or transparent orthography — like Finnish, Spanish, and Italian — have highly consistent letter-to-sound mappings, meaning words are…

Overselectivity(also: Stimulus Overselectivity, Overselective Attention)

A learning challenge in which an individual attends to only one or a few features of a stimulus while ignoring other relevant features, resulting in an inability to discriminate between stimuli that share some characteristics. For example, a child who is overselective might…

Pacing Aid(also: Pacing System, Time Management Aid)

An assistive technology that helps individuals with cognitive impairments manage the timing and sequence of activities in daily routines. Pacing aids provide cues — visual, auditory, or tactile — to indicate whether the user is on schedule, ahead, or behind, without requiring…

Pain Invalidation(also: chronic pain disbelief, pain dismissal)

The experience of having one's pain dismissed, disbelieved, or minimised by others, including healthcare professionals, family members, and social contacts. Pain invalidation is a pervasive barrier for people with chronic pain conditions, particularly primary pain syndromes such…

Pain Self-Management(also: chronic pain self-management)

A person-centred approach to living with chronic pain in which the individual takes an active role in managing their own condition through daily coping strategies, behavioural adaptations, and use of support resources, rather than relying solely on clinical interventions. Pain…

Paradox of the Active User

The Paradox of the Active User, identified by Carroll and Rosson (1987), refers to the observation that computer users systematically avoid investing time in learning more efficient tools or methods, even when doing so would yield significant long-term productivity gains. Users…

Path Integration

A cognitive navigation process in which a person tracks their position relative to a starting point by continuously monitoring their movements — including direction changes, distance traveled, and turns taken. People who are blind rely heavily on path integration when navigating…

Pattern Glare

A visual perceptual phenomenon where repeated striped or lined patterns cause discomfort, headaches, eyestrain, or visual distortions such as flickering, shimmering, or apparent movement. Pattern glare particularly affects people with dyslexia, epilepsy, and migraine, and can be…

People with Dementia(also: PwD)

A person-first term used in accessibility and dementia research to refer to individuals living with dementia — an umbrella term covering progressive neurological conditions (such as Alzheimer's disease, vascular dementia, Lewy body dementia, and frontotemporal dementia) that…

Perception-Action Cycle(also: PAC)

In human-computer interaction research, the perception-action cycle (PAC) describes the continuous loop in which a user perceives information from the environment — such as the position of an on-screen element — and uses that perception to guide a motor action. The term…

Perceptual Bandwidth(also: Sensory Bandwidth, Information Bandwidth)

Perceptual bandwidth refers to the rate at which a sensory channel can transmit information to the brain. In accessibility contexts, the concept highlights the fundamental asymmetry between vision and hearing: vision has extremely high bandwidth, allowing a sighted person to…

Perceptual Guidance

An instructional technique that directs a user’s attention to specific perceptual features of a target — most commonly color and on-screen location — to help them detect or disambiguate it. In accessibility contexts, perceptual guidance is used in screen-reader cues, tutorial…

Perceptual speed(also: Processing speed, Cognitive processing speed)

The speed at which an individual can accurately perceive, compare, and respond to visual or auditory stimuli, typically measured through timed tasks requiring rapid symbol comparison or pattern matching. Perceptual speed declines with age and is a significant predictor of…

Peripheral Awareness(also: Peripheral Perception, Ambient Awareness)

The innate ability to unconsciously maintain and constantly update a sense of one's social and physical surroundings without actively directing attention to them. In accessibility contexts, peripheral awareness is critical for social interaction, as sighted people effortlessly…

Perseveration(also: Perseverative Behavior)

The uncontrolled repetition of a response, word, phrase, or action that persists beyond the appropriate context. In people with cognitive impairments such as dementia, brain injury, or certain developmental disabilities, perseveration can manifest as repeatedly pressing the same…

Personal Data Externalization(also: Data Externalization)

The process of representing internal experiences — thoughts, emotions, behaviours, bodily states — in some external medium such as a drawing, written word list, spreadsheet, physical artefact, or tracking log. Drawing on Larkin and Simon's distinction between internal and…

Personalization Semantics(also: WAI-Adapt)

A W3C specification that defines standardized semantics enabling content to be adapted to individual user needs and preferences. Personalization Semantics allows web authors to add metadata attributes to HTML elements that describe their purpose, importance, or function in a way…

Personalized Learning(also: Adaptive Learning, Individualized Instruction, Differentiated Instruction)

Personalized learning is an educational approach that tailors content, pace, and delivery method to each learner's individual needs, preferences, and abilities. In accessibility contexts, personalization goes beyond selecting appropriate difficulty levels — it requires creating…

Phonological Awareness(also: Phonemic Awareness, Sound Awareness)

The ability to recognize and manipulate the sound structures of spoken language, including syllables, rhymes, and individual phonemes. Phonological awareness is a foundational skill for reading and writing, and deficits in phonological processing are considered a core…

Phonological Processing(also: Phonological Awareness, Phonemic Awareness)

The ability to recognize and manipulate the sound structures of language, including identifying individual phonemes, blending sounds together, and segmenting words into their component sounds. Phonological processing is a core skill for reading acquisition and is one of the…

Pictograms(also: Pictogram, Picture Symbols, PCS)

Simplified pictorial symbols that represent concepts, objects, activities, emotions, or places, widely used as a form of augmentative and alternative communication (AAC) and as a visual support for autistic individuals, minimally verbal users, and people with cognitive…

Pictograph(also: Pictogram, Picture Symbol, Graphic Symbol)

A simplified visual symbol or image that represents a word, concept, or action, used as an alternative or supplement to written text. Pictograph systems such as Sclera, Beta, and Widgit are widely used in augmentative and alternative communication (AAC) to support people with…

Picture Prompting(also: Visual prompting, Pictorial instruction)

An instructional strategy that uses photographs or illustrations to depict how to complete each step of a task, providing visual guidance for people with developmental or intellectual disabilities. Picture prompts can be delivered through physical cards, printed instructions, or…

Plain Language(also: Plain English, Clear Language, Simple Language)

Plain language is communication that is clear, concise, and well-organized so that the intended audience can easily find, understand, and use the information. In accessibility, plain language is essential for making content accessible to people with cognitive disabilities, low…

PrEmo(also: Product Emotion Measurement Instrument)

A non-verbal self-report tool for measuring emotional responses, developed by Pieter Desmet. PrEmo presents users with 14 cartoon-like icons representing seven positive emotions (joy, admiration, pride, hope, satisfaction, fascination, desire) and seven negative emotions…

Practice Effects(also: Test-Retest Practice Effects, Familiarity Effects)

Practice effects in cognitive assessment refer to the improvement in test scores that occurs not from genuine cognitive change but from increased familiarity with test content and format across repeated administrations. They are a significant limitation of fixed-content…

Prior Authorization(also: Pre-Authorization, Pre-Auth, PA)

A requirement by health insurance companies that a healthcare provider obtain approval before a prescribed medication or treatment is covered. Prior authorization processes often involve multi-step bureaucratic procedures — submitting documentation, waiting for review, handling…

Proactive Prompt(also: Proactive Cue)

In voice-interface and conversational-agent design, a system-initiated utterance or visual cue that surfaces a suggestion, reminder, or next step without the user first asking. Examples include suggesting the weather at a user's usual wake-up time, reminding someone to take…

Procedural task analysis(also: Task decomposition, Step-by-step analysis)

A method of breaking down complex tasks into sequential, discrete steps to understand user workflows and identify points of difficulty. In accessibility contexts, procedural task analysis reveals where users with cognitive, sensory, or motor impairments encounter barriers — such…

Process Model of Emotion Regulation(also: Gross Process Model)

A theoretical framework developed by James Gross that conceptualizes emotion regulation as a dynamic, continuous process with four main stages: identification (recognizing an emotion that needs regulation), selection (choosing a regulation strategy such as situation selection,…

Processing Speed(also: Information Processing Speed, Cognitive Processing Speed)

A cognitive ability referring to how quickly a person can perceive, process, and respond to information. Processing speed affects how rapidly someone can read, understand instructions, react to stimuli, and complete timed tasks. It naturally declines with age, beginning in…