Glossary

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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…

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…

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 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…

Plan Recognition(also: Intent Prediction, Action Prediction)

A technique in human-computer interaction where a system predicts the user's intended action based on patterns in their input behaviour and the current interaction context. By anticipating what the user is likely to do next, the system can weight recognition processes…

Pluggable User Interface(also: Pluggable UI, Alternative User Interface)

A pluggable user interface is an interchangeable interface component that can be swapped in or out of an application without changing the application's core functionality. In the Universal Remote Console (URC) framework, pluggable user interfaces connect to an abstract "user…

Pointing Device(also: Pointer Device, Input Device)

Any hardware device used to control the movement of a cursor or pointer on a computer screen, enabling users to select, click, drag, and interact with interface elements. Common pointing devices include the mouse, trackball, trackpad, touchscreen, stylus, joystick, head-tracking…

Pointing Device Gain(also: Control-Display Gain, Mouse Sensitivity, Pointer Speed)

The ratio between the movement of a physical input device (such as a mouse or trackball) and the resulting movement of the cursor on screen, typically measured in pixels per inch of device movement. Higher gain means the cursor moves further for a given physical movement. In…

Portable Reader(also: Portable Reading Device, Portable Reading Machine)

An assistive technology device that combines a camera or scanner with optical character recognition and text-to-speech output to enable blind or visually impaired users to read printed text independently in any location. Unlike traditional flatbed scanner-based reading systems…

Pose estimation(also: Body pose estimation, Human pose estimation)

The computational process of determining the position and orientation of a person's body joints and limbs from sensor data such as cameras, depth sensors, or inertial measurement units. In accessibility contexts, pose estimation enables applications like gesture-based…

Postural Support(also: Seating Support, Positioning Support)

Equipment and strategies that help maintain a person's body in a stable, functional position for activities including communication, eating, and using assistive technology. Adequate postural support is a prerequisite for many assistive technologies, particularly gaze-based…

Posture Detection(also: Posture Monitoring, Posture Recognition)

The use of sensors or computer vision to identify and monitor a person's body posture in real time. In assistive technology, posture detection systems can use accelerometers, gyroscopes, or cameras to determine whether a user is sitting, standing, slouching, or hunching, and…

Power Assist Device(also: Power assist wheel, Pushrim-activated power-assisted wheelchair, PAPAW)

A motorized attachment that adds electric propulsion assistance to a manual wheelchair without converting it into a full power wheelchair. Power assist devices typically attach to the wheelchair frame, wheels, or axle and amplify the user's pushing force, reducing physical…

Power Cards

Power Cards are a visual teaching strategy developed by Elisa Gagnon for autistic learners and others with social-communication differences. A Power Card is a small, portable card that pairs a brief scenario about a child's special interest (such as a favourite character) with a…

Power Wheelchair(also: Electric Wheelchair, Motorized Wheelchair, Power Chair)

A wheelchair propelled by an electric motor rather than manual pushing, essential for people with severe motor disabilities who lack the upper body strength or dexterity to operate a manual wheelchair. Power wheelchairs are typically controlled through joysticks, but alternative…

Power-Assist Add-On(also: Power Assist, Power-Assist Device, Wheelchair Power Assist)

A power-assist add-on is a retrofit device attached to a manual wheelchair that provides motorized propulsion while preserving the chair's manual structure, offering a middle ground between manual and full power wheelchairs. Commercial examples include the SmartDrive, Firefly,…

Powered Wheelchair(also: Electric Wheelchair, Motorized Wheelchair, Power Chair)

A wheelchair propelled by an electric motor and battery system rather than manual effort, typically controlled via a joystick or alternative input device. Powered wheelchairs are essential mobility aids for individuals who lack the upper body strength or coordination to operate…

Pre-Programmed Message(also: Stored Message, Canned Response, Pre-Set Phrase)

A message or phrase stored in an AAC device that can be quickly retrieved and spoken without requiring real-time composition. Pre-programmed messages trade expressiveness for speed—they enable faster communication but are limited to anticipated phrases. For backchanneling,…

Pre-compensation(also: Display Pre-compensation, Image Pre-compensation)

A technique in which images displayed on a computer screen are mathematically modified in advance to counteract the visual aberrations of the viewer's eye. Rather than relying on corrective lenses or magnification, pre-compensation transforms the source image so that when it…

Precompensation(also: Display Precompensation, Image Precompensation)

A technique in visual accessibility that pre-modifies displayed images in a way that is opposite to the optical distortion introduced by a user's eye, so that the image arriving at the retina more closely resembles the intended original. Precompensation works analogously to an…

Prediction Utilization(also: PU)

The percentage of opportunities where a user accepts a word prediction rather than continuing to type the word manually. Prediction utilization reflects user trust in a prediction system—higher quality predictions lead to higher utilization rates. Research shows that users…

Predictive Cursor(also: Anticipatory Cursor, Offset Cursor)

A cursor display technique designed to compensate for the delays inherent in speech-based or other high-latency input methods. A predictive cursor shows an indicator ahead of the actual cursor position, offset by the estimated distance the cursor will travel during the input…

Predictive Disambiguation(also: Dictionary-based Predictive Disambiguation, DBPD, Word Disambiguation)

Predictive disambiguation is the class of text-entry techniques in which each user input event is intentionally ambiguous (one keystroke covers several possible letters, one swipe covers many possible paths) and software resolves the ambiguity into a most-likely word using a…

Predictive Text(also: Text Prediction, Word Prediction, Autocomplete)

A software feature that suggests words or phrases as the user types, based on context, language models, and the user's typing history. Predictive text is a significant accessibility feature for people with motor impairments because it reduces the number of keystrokes needed,…

Preference Customization(also: User Preference Configuration, Personalization Settings)

The ability for users, particularly those using assistive technologies, to configure how they receive and interact with digital content based on their individual needs, preferences, and context. In accessibility, preference customization goes beyond basic assistive technology…

Press-and-Listen Paradigm(also: Sequential Navigation, Linear Content Consumption)

The fundamental interaction model of screen reader assistive technology, where users press keyboard shortcuts to move through web content elements one at a time and listen to each element being announced sequentially. This paradigm transforms the two-dimensional graphical…

Privacy Leak(also: Accidental Disclosure, Privacy Disclosure)

The unintentional capture and sharing of sensitive personal information through visual assistance technologies. Research has found that approximately 10% of images submitted to VAT services contain private content such as pregnancy tests, prescription medication, and people,…

Privacy Threat Model(also: Privacy Threat Analysis, Privacy Risk Assessment)

A systematic process for identifying, classifying, and evaluating potential privacy risks that a technology system may pose to its users. Privacy threat modeling extends security-focused frameworks (like Microsoft's STRIDE) to address privacy-specific concerns. The LINDDUN…

Proactive description(also: Proactive notification, Unsolicited description)

The ability of an assistive system to automatically provide relevant visual or environmental information without requiring the user to explicitly request it. For blind and visually impaired users navigating real-world environments, proactive description is critical — a human…

Procedural Feedback System(also: Process-Oriented Guidance System)

An assistive technology paradigm that provides dynamic, step-by-step support throughout complex multi-step tasks rather than addressing isolated moments of need. Unlike traditional assistive tools that help with discrete actions (e.g., identifying a color or reading a label),…

Procedural Task Tracking(also: Task Progress Tracking, Step Tracking)

The automated monitoring of a user's progress through a multi-step task, identifying which steps have been completed, which are in progress, and which remain. In accessibility contexts, procedural task tracking enables assistive systems to provide context-sensitive guidance…

Product Identification(also: Product Recognition)

The task of determining what a packaged or unpackaged product is from visual (or other sensory) input, at a level of detail useful to an end user: generic type (soup, cereal, shampoo), brand (Campbell's, Kellogg's, Dove), and variety or flavour (tomato vs. chicken noodle; 90%…

Programming by Demonstration(also: PBD, Record and Replay, Macro Recording)

A technique for creating automated sequences of actions by recording a user performing the task manually, rather than requiring the user to write code or scripts. The system observes the user's interactions (clicks, keystrokes, form inputs) and generates replayable instructions.…

Prompting System(also: Prompting Device, Task Prompting Technology)

An assistive technology that provides stepwise guidance through text, images, audio, or video instructions to help individuals complete multi-step tasks such as cooking, personal hygiene, or workplace activities. Prompting systems are widely used to support people with cognitive…

Prosthesis(also: Prosthetic, Prosthetic Device, Artificial Limb)

A prosthesis is an artificial device that replaces a missing body part, which may be lost through congenital conditions, injury, or disease. Prostheses range from purely cosmetic devices designed to replicate natural appearance, to functional devices that restore some degree of…

Prosthesis(also: Prosthetic, Prosthetic device, Artificial limb)

A prosthesis is an artificial device that replaces a missing body part, most commonly a limb. Prosthetics range from cosmetic devices that restore appearance to functional devices that enable specific activities. Modern prosthetics may include mechanical components, myoelectric…

Prosthetics(also: Prostheses, Prosthetic Devices, Artificial Limbs)

Artificial devices designed to replace missing body parts, most commonly limbs lost through amputation, congenital absence, or trauma. Modern prosthetics range from basic cosmetic devices to highly functional myoelectric arms controlled by muscle signals and…

Proxemic Interaction(also: Proximity-Based Interaction, Proxemics)

An interaction design approach that uses the spatial relationship between users, devices, and objects in the environment — including distance, orientation, and movement — to trigger contextual actions and content delivery. Derived from Edward T. Hall's theory of proxemics (the…

Proximity Detection(also: Proximity Sensing, Proximity-Based Localization)

A method of determining a user's approximate location by measuring their closeness to known reference points, such as BLE beacons or Wi-Fi access points, based on signal strength. In accessible indoor navigation systems, proximity detection is used to localize users at specific…

Proxy(also: Support Person, Intermediary User)

In accessibility contexts, a person who assists someone with a disability in using technology or accessing services. Proxies may include family members, caregivers, support workers, or friends who help with tasks ranging from physical operation of devices to interpretation of…

Proxy Interface(also: Accessibility Proxy, Alternative Interface)

An intermediary user interface that sits between the user and the original content, re-presenting information in a more accessible format without modifying the underlying source. In accessibility contexts, proxy interfaces are used to transform visually-encoded content (like…

Proxy User(also: Proxy Participant, Surrogate User)

A person without a disability who participates in research or usability testing as a stand-in for the intended end user with a disability. Proxies are commonly used in AAC and assistive technology research to circumvent challenges in recruiting and communicating with…

Psychosocial Impact of Assistive Devices Scale(also: PIADS)

A 26-item self-report questionnaire designed to measure the psychosocial impact of an assistive technology device on a person's functional independence, well-being, and quality of life. PIADS assesses three subscales: competence (subjective feelings of competence, productivity,…

Public Digital Terminal(also: PDT, Self-Service Terminal, Self-Service Kiosk)

A publicly available interactive electronic device that provides services or information to users, such as ATMs, ticket vending machines, check-in kiosks, and information points. Public digital terminals present significant accessibility challenges because users cannot install…

Pull Notification(also: On-Demand Notification, User-Initiated Notification)

A notification or information delivery model where content is provided only when explicitly requested by the user, in contrast to push notifications which are delivered automatically. In assistive navigation contexts, pull notifications allow blind users to request specific…