Glossary

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Phoneme-Grapheme Mapping(also: Phoneme-Grapheme Correspondence, Alphabetic Principle)

The relationship between speech sounds (phonemes) and their written representations (graphemes), which is foundational to reading in alphabetic writing systems. Mastering phoneme-grapheme mapping — the alphabetic principle — is essential for fluent word recognition and a key…

Phonemic Spelling(also: Phonetic Spelling)

The practice of spelling words based on their pronunciation rather than their conventional orthography, used as a workaround when text-to-speech systems do not support a desired language. In AAC contexts in Ghana, speech and language therapists experimented with typing English…

Phonocentrism

The ideological privileging of spoken language as the default and superior mode of communication, with corresponding devaluation of signed, typed, symbolic, or augmentative forms. In accessibility, phonocentrism surfaces when technologies (voice assistants, automatic speech…

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 Development(also: Speech Sound Development, Phonological Acquisition)

The process by which children learn to produce and organise the speech sounds of their language, progressing from early cooing and vowel-like sounds through canonical babbling (consonant-vowel syllables) to recognisable words and complex phonological patterns. Phonological…

Phonological Dyslexia

A subtype of dyslexia characterized by difficulty with sound-based word decoding, including problems with orthographically similar words (e.g., confusing "addition" and "audition"), number and letter recognition, and errors related to word substitutions, additions, or omissions.…

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…

Phonology(also: Sign Language Phonology)

The study of the smallest meaningful units that make up language and the rules governing their combination. In sign languages, phonology describes the building blocks of signs: handshape, location on the body, movement, palm orientation, and non-manual signals. William Stokes…

Phonophobia(also: Sound Phobia, Ligyrophobia)

Phonophobia is an intense fear or aversion to specific sounds or loud noises that goes beyond simple discomfort, often leading to avoidance behaviors such as fleeing from environments where triggering sounds may occur. Unlike hyperacusis (heightened sensitivity to sound volume)…

Photo Sharing(also: Photograph Sharing, Image Sharing)

The activity of showing, distributing, or discussing photographs with others — in person, via email, or through social-networking platforms. As a social practice it conveys memories, experiences, and identity; as an accessibility concern it presents barriers for blind and…

Photo-based Communication(also: Visual Communication Aid, Image-based Communication)

A communication strategy that uses photographs or images as the primary medium for conveying meaning, sharing experiences, and supporting conversation. For people with aphasia, intellectual disabilities, or other conditions that affect spoken and written language, photographs…

Photoparoxysmal Response(also: PPR, Photosensitive Response)

An abnormal brain response to flashing lights or patterns, detected through electroencephalogram (EEG) monitoring during intermittent photic stimulation. A photoparoxysmal response indicates photosensitivity and potential risk for photosensitive epilepsy, though not everyone who…

Photophobia(also: Light Sensitivity)

A genuine physiological sensitivity to bright light, flickering light, or intense visual patterns that causes symptoms such as headaches, migraines, nausea, dizziness, and disorientation. Despite its name suggesting a psychological fear, photophobia involves real neurological…

Photoplethysmography(also: PPG)

A non-invasive optical technique used to detect blood volume changes in peripheral circulation, commonly implemented in wearable devices like smartwatches and fitness trackers. PPG sensors use light (typically red and green LEDs) to measure how blood flow absorbs and reflects…

Photosensitive epilepsy(also: PSE, Photosensitivity, Visually-provoked epilepsy)

A form of epilepsy in which seizures are triggered by visual stimuli such as flashing lights, strobing effects, rapid colour transitions, or high-contrast repeating patterns. It affects approximately 3 to 5 percent of people with epilepsy and is more common in children and…

Photosensitivity(also: Photosensitive Epilepsy, PSE)

A neurological condition in which exposure to flickering light patterns, flashing graphics, or rapid luminance changes triggers physiological responses including seizures, migraines, nausea, dizziness, and disorientation. Photosensitive epilepsy, the most dangerous form, affects…

Photosensitivity(also: Light Sensitivity, Photophobia)

An abnormal sensitivity to light that can cause discomfort, pain, or visual disturbance. Photosensitivity affects many people with visual impairments and certain neurological conditions including migraine and epilepsy. In digital accessibility, photosensitivity considerations…

Phrase-Based Communication(also: Phrase-Based AAC, Pre-Stored Phrase Communication)

An augmentative and alternative communication approach where users select complete pre-composed phrases or sentences rather than constructing messages letter by letter or word by word. Phrase-based systems offer faster communication rates than spelling-based methods, which is…

Physical Accessibility(also: Physical Access, Architectural Accessibility)

Physical accessibility refers to the design of buildings, environments, and public spaces so they can be independently used by people with physical disabilities, including those who use mobility aids. It encompasses features such as ramps, elevators, accessible restrooms,…

Physical Agency(also: Bodily Agency, Sense of Agency)

The feeling of control and ownership over physical actions and their effects in the world. In assistive technology contexts, physical agency refers to a users sense of directly controlling objects and receiving sensory confirmation of their actions. Traditional AT designs often…

Physical Control(also: Direct Control, Direct Manipulation)

An interaction paradigm where the user directly manipulates on-screen objects or controls by pointing to them and acting on them, as with a mouse click or touch screen tap. In physical control, the focus or cursor moves among all visible interface elements, and the user must…

Physical Crowdsourcing(also: Spatial Crowdsourcing, Physical World Crowdsourcing)

A form of crowdsourcing in which tasks require participants to perform actions in the physical world rather than completing digital tasks online. In an accessibility context, physical crowdsourcing has been applied to installing and maintaining navigation infrastructure such as…

Physical Disability(also: Motor Disability, Physical Impairment)

A condition that affects a person's physical functioning, mobility, dexterity, or stamina. Physical disabilities include conditions such as paralysis, amputation, muscular dystrophy, cerebral palsy, spinal cord injury, multiple sclerosis, and arthritis. In technology and VR…

Physical Guidance(also: Hands-On Guidance, Physical Assistance)

A body movement teaching technique in which an instructor physically moves or positions a student's body to demonstrate correct form, rhythm, or placement. Physical guidance is widely used in teaching dance, sports, and martial arts to blind and low vision students, as it…

Physical Layer Accessibility

The dimension of VR accessibility concerned with whether users can physically access and operate VR hardware and interaction paradigms. This includes the setup process (putting on head-mounted displays, adjusting straps), manipulating controllers or using hand tracking, and…

Physical Rehabilitation(also: Physiotherapy, Physical Therapy)

A therapeutic process aimed at restoring, maintaining, or improving physical function, mobility, and strength through structured exercises and interventions. Physical rehabilitation is essential for people with motor disabilities, injuries, or neurological conditions to regain…

Physical Therapy(also: Physiotherapy, PT)

A healthcare profession focused on evaluating and treating physical impairments, functional limitations, and disabilities through movement, exercise, manual therapy, and assistive devices. Physical therapists work with people recovering from injuries, surgeries, strokes, and…

Physiological Computing(also: Biometric Computing, Biosignal-based Computing)

A computing paradigm that uses real-time physiological signals from the body to inform system responses and adaptations. Common signals include heart rate (via photoplethysmography), skin conductance (galvanic skin response), respiration, and brain activity (EEG). In…

Physiological Sensing(also: Biosensing)

Measuring bodily signals - such as heart rate, galvanic skin response, skin temperature, respiration, or muscle activity - to infer aspects of a user's physical or affective state. Physiological sensing is widely used in accessibility, affective computing, and digital health to…

Pico Projection(also: Pico Projector, Pocket Projector, Mini Projection)

A compact projection technology that enables small, portable devices to project images and information onto nearby surfaces. In accessibility contexts, pico projection offers an alternative to screen-based interfaces by allowing users to project communication props, maps,…

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 Communication Symbols(also: PCS, Boardmaker Symbols)

A widely used graphic symbol system for augmentative and alternative communication (AAC), consisting of simple, colorful line drawings representing words, phrases, and concepts. Developed by Mayer-Johnson (now part of Tobii Dynavox), PCS is one of the most common symbol sets…

Picture Exchange Communication System(also: PECS)

A structured augmentative and alternative communication (AAC) system that teaches individuals to use pictures to communicate with others. Developed by Andrew Bondy and Lori Frost in 1985, PECS uses a series of six phases to teach individuals — typically children with autism or…

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…

Picture Smart AI(also: JAWS Picture Smart AI)

Picture Smart AI is a feature of the JAWS screen reader (Freedom Scientific/Vispero) that uses multimodal AI models to describe images, charts, and on-screen content on demand. It can describe a photo, explain a chart, read text embedded in an image, or answer follow-up…

Picture-in-Picture(also: PiP, PIP)

A display technique that shows a smaller video or content window overlaid on the main content, allowing viewers to see two sources simultaneously. In accessibility contexts, picture-in-picture is the primary method for presenting sign language interpretation in video and…

Pidgin Signed English(also: PSE, Contact Signing, Sign Supported English)

A hybrid communication system that combines elements of American Sign Language (ASL) and English. In PSE, signers use ASL signs for the main content words of an English sentence, following English word order, but generally do not include extra signs for English word endings or…

Pie Menu(also: Radial Menu, Circular Menu)

A pie menu is a circular or ring-shaped menu interface in which command options are arranged radially around a central point, allowing selection by moving the cursor or making a directional gesture toward the desired item. Unlike linear drop-down menus, pie menus leverage…

Piezo Vibrator(also: Piezoelectric Vibrator, Piezoelectric Actuator)

A device that converts electrical signals into mechanical vibrations using the piezoelectric effect, commonly used in tactile displays and haptic feedback systems for assistive technology. Piezo vibrators can be arranged in arrays to create tactile patterns that convey spatial…

Piezoelectric Actuator(also: Piezo Actuator, Piezoelectric Bimorph)

A device that converts electrical energy into precise mechanical motion using the piezoelectric effect — the property of certain materials to change shape when an electric voltage is applied. In assistive technology, piezoelectric actuators are the dominant mechanism used in…

Piggyback Prototyping(also: piggyback prototype, parasitic prototyping)

Piggyback prototyping is a research methodology in which researchers add new features or interventions to already-deployed, live systems rather than building standalone prototypes, enabling study of user behaviour with novel features in authentic real-world contexts. The…

Pilot (Shared Control)

In shared-control video gaming, the pilot is the primary player — usually a person with a disability — who drives the gameplay and makes strategic decisions, while delegating specific inaccessible inputs to a copilot. The pilot retains leadership of the session and, in most…

Pilot-Passenger Model(also: Pilot/Passenger Framework)

A model describing household technology dynamics where "pilots" are the users who set up and configure devices, while "passengers" are those who simply use the systems configured for them. In disability contexts, disabled users may be forced into the passenger role due to…

Pin Array(also: Pin Matrix, Pin-Matrix Display)

A grid of individually controllable pins used in refreshable tactile displays to create tactile images and text. Each pin can be raised or lowered electronically, and in some displays raised to multiple heights, allowing the representation of graphical content through touch. Pin…

Pin Array Display(also: Pin Matrix Display, Tactile Pin Display)

A type of tactile display technology that uses an array of individually controllable pins that can be raised or lowered to create tactile patterns, textures, and graphics. Pin array displays are used in 2D tactile displays to present graphical information such as diagrams,…

Pin-Matrix Display(also: Tactile Pin Display, Pin Array Display, Two-Dimensional Braille Display)

A refreshable tactile display technology that uses a grid of individually controllable pins to create two-dimensional tactile images, as opposed to single-line refreshable Braille displays that show only one row of characters. Pin-matrix displays like the BrailleDis 7200 can…

Pitch

The perceived highness or lowness of a sound, determined primarily by its fundamental frequency (measured in Hertz). Pitch is one of the primary dimensions along which music and speech are organized, underpinning melody, harmony, and prosody. In accessibility work, pitch is…

Pitch Detection(also: Pitch Tracking, Fundamental Frequency Detection)

The computational process of determining the fundamental frequency (pitch) of an audio signal in real time. In accessibility, pitch detection is used in non-speech voice interfaces where changes in humming or vocal pitch are mapped to control commands — for example, a rising…

Pitch Mapping(also: Pitch-Y Mapping, Frequency Mapping)

A sonification technique that maps data values to auditory pitch, where higher values produce higher-pitched sounds and lower values produce lower-pitched sounds. In accessibility contexts, pitch mapping is commonly used to represent the vertical position (Y-axis) of data points…