Glossary

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P300(also: P3, P300 Component, P3b)

The P300 is an event-related potential (ERP) component — a positive voltage deflection in EEG brain signals that peaks approximately 300 milliseconds after a person perceives a rare or task-relevant stimulus among frequent non-target stimuli. It is named for its polarity…

PC-Talker(also: PCTalker)

A Windows screen reader developed by the Japanese company KGS Corporation, widely used by blind and low-vision users in Japan. PC-Talker provides speech output for Windows applications and the web and integrates with the companion Net Reader Neo browser tailored to…

PDF Remediation(also: PDF Tagging, PDF Accessibility Remediation, Document Remediation)

The process of adding structural tags to an existing PDF document to make it accessible to assistive technologies such as screen readers. Remediation involves identifying logical content elements (headings, paragraphs, lists, tables, images), assigning appropriate tags,…

PHANTOM(also: PHANTOM Omni, PHANTOM Desktop, SensAble PHANTOM)

A family of force-feedback haptic devices originally developed by SensAble Technologies (now part of 3D Systems). PHANTOM devices use a pen-like stylus that users grasp while motors apply forces to create the sensation of touching virtual objects or being guided along…

PS5 Access Controller(also: PlayStation Access Controller, Access Controller)

Sony's highly customisable controller for PlayStation 5, released in 2023 and designed for players with limited motor control. It has a flat disc layout with interchangeable button caps and analog stick attachments, 3.5 mm expansion ports for external switches, and…

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…

Page Magnification(also: Page Zoom, Web Page Magnification)

An accessibility feature that enlarges the entire visual presentation of a web page, including text, images, and layout elements, to make content easier to see for people with low vision or visual fatigue. Unlike text-only size increases, page magnification scales all page…

Page Turner(also: Page Turning Aid)

Any device, tool, or person that assists a musician in turning the pages of a music score during performance. Traditional page turners are human assistants who sit beside a musician and turn pages on cue. Technological alternatives include Bluetooth foot pedals for digital…

Panning(also: Screen Panning, Viewport Panning)

The act of moving the visible area of a screen magnifier or viewport across a webpage or application to view content that extends beyond the currently displayed portion. For screen-magnifier users, panning is a fundamental but often arduous interaction technique, requiring…

Pantograph(also: Haptic Pantograph)

A haptic input device that allows users to explore a two-dimensional surface by physically moving a stylus or finger pad across an exploration area, while receiving tactile feedback from an attached tactile display. In accessibility applications, the pantograph enables people…

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…

Parallax(also: Visual Parallax, Binocular Parallax)

Parallax is the apparent displacement or difference in position of an object when viewed from two different vantage points. In human vision, binocular parallax — the slight difference between the images seen by each eye due to their spatial separation — is a primary cue for…

Parametric design(also: Parametric modeling)

A design approach in which objects are defined by adjustable parameters (dimensions, angles, ratios) rather than direct geometric manipulation, allowing users to customize designs by changing numerical values without needing 3D modeling expertise. Parametric design is…

Passive Infrared Sensor(also: PIR Sensor, PIR, Motion Sensor)

A passive infrared sensor detects movement by measuring changes in ambient infrared radiation in its field of view — typically body heat from a person moving across the detection zone. PIR sensors are inexpensive, low-power, and require no active emission, which makes them a…

Passive Pin Retention

A mechanical technique used in refreshable Braille display design where pins are held in their raised or lowered positions by a passive mechanical structure rather than by continuously powered actuators. In traditional Braille displays, each pin requires its own actuator to…

Passive Sensing(also: Passive Monitoring, Ambient Sensing)

The collection of behavioral and physiological data through sensors without requiring active user input. In mental health contexts, passive sensing uses smartphone sensors (GPS, accelerometer, microphone), wearable devices (heart rate monitors, electrodermal activity sensors),…

Passive notification(also: Automatic notification, Push notification)

Information delivered to a user automatically without requiring active input, triggered by context such as location, time, or system state. In assistive navigation for people with visual impairments, passive notifications are preferred because users' hands and attention are…

Pedestrian Dead Reckoning(also: PDR, Inertial Navigation)

A localization technique that estimates a pedestrian's position by tracking their movement from a known starting point using inertial sensors (accelerometers and gyroscopes) found in smartphones. The accelerometer detects individual steps through peak detection, while the…

Pedestrian Detection(also: Person Detection, Human Detection)

A computer vision task that identifies and locates people in images or video frames, typically using deep learning models such as convolutional neural networks. In accessibility applications, pedestrian detection is used in wearable assistive technologies for blind and low…

Pedestrian Navigation System(also: Pedestrian GPS, Walking Navigation)

A navigation system designed specifically for people travelling on foot, as opposed to systems designed for car drivers. Pedestrian navigation systems must account for footpaths, crosswalks, stairs, pedestrian bridges, and indoor routes that vehicle-focused systems typically…

Peltier Module(also: Peltier Device, Thermoelectric Module, TEC Module)

A Peltier module is a thermoelectric device that creates a temperature difference when electrical current is applied, with one side heating up and the other cooling down. In assistive technology, flexible Peltier modules are used to provide thermotactile feedback — controlled…

Pen-based Interface(also: Stylus Interface, Pen Computing, Digital Pen Interface)

A computer interaction method that uses a stylus or digital pen as the primary input device, typically in combination with a graphics tablet or touchscreen. Pen-based interfaces can support handwriting recognition, gesture commands, and direct manipulation of on-screen objects.…

People with Severe Motor Disabilities(also: PSMD)

A term used in assistive technology and human-robot interaction research to describe individuals whose motor impairments are severe enough that they cannot reliably use their hands or arms for everyday tasks, and who therefore depend on hands-free control modalities such as eye…

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 Computing(also: Perceptual Intelligence)

A computing paradigm in which systems use sensors such as cameras, microphones, and motion detectors to perceive and interpret human behaviour, including gestures, facial expressions, speech, and body movement. In accessibility contexts, perceptual computing enables interfaces…

Perceptual User Interface(also: PUI, Natural User Interface)

A human-computer interaction paradigm that uses natural human capabilities such as vision, speech, gestures, and body movement as input modalities rather than relying on traditional devices like keyboards and mice. Perceptual user interfaces leverage sensors and computer vision…

Perkins Brailler(also: Brailler, Braille Writer)

A mechanical device for writing braille, manufactured by the Perkins School for the Blind since 1951. The Perkins Brailler has six keys corresponding to the six dots of a braille cell, a space bar, a backspace key, and a line advance key, allowing users to emboss braille…

Person-Technology Match(also: PTM, Matching Person and Technology)

A systematic approach to selecting assistive technology by evaluating the fit between a person's specific abilities, needs, preferences, and environment and the features and demands of available technologies. The person-technology match process recognizes that the most…

Personal Assistant(also: Virtual Assistant, Digital Assistant, Voice Assistant)

A software agent that can perform tasks or provide services based on user commands or queries, typically through voice interaction. Popular examples include Amazon Alexa, Google Assistant, Apple Siri, and Microsoft Cortana, often embedded in smart speakers, smartphones, and…

Personal Digital Assistant(also: PDA, Handheld Computer, Pocket PC)

A portable handheld computing device popular in the late 1990s and early 2000s that combined features like a calendar, contacts, note-taking, and basic application support in a pocket-sized form factor with a touchscreen interface. In accessibility research, PDAs like the iPAQ…

Personal Object Recognizer(also: Teachable Object Recognizer, Custom Object Classifier)

A computer vision system that allows individual users to train their own object recognition models by providing a small number of example photos and custom labels. Unlike generic object recognizers that use pre-defined categories, personal object recognizers let users define…

Personal Safety Management(also: PSM)

Personal Safety Management refers to the informed, agential, and proactive participation of an individual in maintaining their own physical safety. Coined in accessibility research by Branham et al. (2017), the concept highlights how people with disabilities — particularly those…

Personal Voice(also: Voice Banking, AI Voice Clone)

A technology that creates a synthetic replica of a person's voice from recorded speech samples, enabling text-to-speech output that sounds like the individual rather than a generic electronic voice. Apple's Personal Voice feature (iOS 17+) allows users to train an AI model of…

Personal emergency response system(also: PERS, PER system, Medical alert system)

A device, typically a wearable pendant or wristband with a button, that allows a person to summon help in an emergency. Despite being the mainstream solution for older adults living alone, PERS devices suffer from poor adoption: users forget to wear them, find them stigmatizing,…

Personal-Scale Manufacturing(also: Desktop Manufacturing, Personal Fabrication)

The use of affordable, accessible manufacturing tools such as 3D printers, laser cutters, and CNC machines by individuals or small groups to produce custom physical objects, as opposed to relying on industrial-scale production. In the context of assistive technology,…

Personalized Object Recognition(also: Teachable Object Recognition)

A class of computer vision systems that allow an individual user — typically someone who is blind or has low vision — to train their device to recognize a small set of personally relevant objects (a specific coffee mug, a particular set of keys, a favourite notebook) by…

Personalized accessibility(also: Customizable accessibility, Adaptive accessibility)

An approach to accessibility that allows users to configure assistive features according to their individual needs, preferences, and abilities rather than providing a single fixed accommodation. Personalized accessibility recognizes that disabilities — particularly conditions…

Personally Identifiable Information(also: PII)

Any data that can be used to identify a specific individual, such as name, email address, location, biometric data, or device identifiers. For assistive technology users, PII concerns are heightened because the data collected often reveals sensitive information about a person's…

Pet Robot(also: Robotic Pet, Zoomorphic Robot, Companion Pet Robot)

A socially interactive robot designed to resemble and behave like an animal companion — most famously PARO (a baby harp seal) and AIBO (a robotic dog) — used to provide emotional comfort, reduce loneliness, stimulate engagement, and support therapy for older adults, particularly…

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…

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…

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 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 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…

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…

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…

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…