Glossary

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Pitch Polarity(also: Pitch Mapping Direction)

The direction in which pitch changes correspond to navigation direction in an auditory interface — specifically, whether pitch increases (ascending polarity) or decreases (descending polarity) as a user scrolls downward through a list or menu. Pitch polarity is a design variable…

Pivotal Response Training(also: PRT, Pivotal Response Treatment)

A naturalistic, child-initiated behavioural intervention developed for children with autism that targets "pivotal" skills — foundational abilities whose improvement produces widespread positive changes across social, communication, and academic domains. Unlike highly structured…

Place Attachment(also: Sense of Place)

Place attachment is the emotional and cognitive bond a person forms with a particular location — a home, neighbourhood, city, or landscape — built up through memory, repeated experience, social ties, and meaning-making. It is studied in environmental psychology, urban planning,…

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…

Plain language(also: Plain English, Easy read, Simple language)

A communication approach that uses clear, concise, and well-organised writing designed to be understood the first time it is read. Plain language avoids jargon, complex sentence structures, and ambiguous wording. It is a key accessibility practice for making information…

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…

Planning Fallacy

A well-documented cognitive bias, identified by Kahneman and Tversky and elaborated by Buehler and colleagues, in which people systematically underestimate how long their own tasks will take and overestimate how much they can finish, even when they have direct evidence that…

Platform Accessibility

The degree to which online platforms (websites, apps, social media, marketplace platforms) are usable by and inclusive of disabled people. Platform accessibility encompasses not only technical compliance with standards like WCAG but also policies, algorithms, and moderation…

Platform Governance(also: Social Media Governance)

Platform governance refers to the policies, rules, procedures, and technical mechanisms through which digital platforms regulate user behaviour, content, and participation. It encompasses both formal rule-making structures — such as community guidelines, terms of service,…

Play-by-Play(also: Play-by-play announcing, Play-by-play commentary)

In sports broadcasting, the moment-to-moment verbal description of on-screen action provided by the main commentator (e.g., who has the puck, who is passing to whom). Because play-by-play describes what sighted viewers can see, it largely duplicates visual information for Deaf…

Playback Speed(also: Video Speed, Playback Rate)

The rate at which video or audio content plays relative to its original recording speed. Most video platforms allow users to adjust playback speed, typically from 0.25x to 2x or higher. For viewers with ADHD, playback speed is an important accessibility feature—faster playback…

Player balancing(also: Dynamic difficulty adjustment, Skill balancing)

A game design technique that provides in-game advantages to lower-performing players, reducing performance disparities between competitors of different ability levels. In the context of accessibility, player balancing through skill assistance — such as aim correction in shooting…

Playful Interaction(also: Playful design)

A design stance that treats play — voluntary, intrinsically motivated, rule-structured activity — as a core property of interactive systems rather than a surface layer of rewards or points. Playful interaction emphasizes the felt experience of users (curiosity, challenge, flow,…

Playhead(also: Play Head, Cursor Position)

The visual indicator on a video or audio timeline that shows the current playback position, typically a vertical line or triangle marker that moves in time with the media. Playheads are a core primitive of timeline-based media tools (video editors, DAWs, subtitle authoring…

Playification

A design strategy that transforms routine or clinical tasks into playful, engaging experiences without relying solely on competitive game mechanics like points and leaderboards. Unlike gamification, which adds game elements to non-game contexts, playification emphasizes…

Playtesting(also: Play testing)

A user-research method in game and interactive-system design in which representative users play an in-development game while researchers observe, collect think-aloud commentary, and conduct follow-up interviews to probe mechanics, engagement, difficulty, and fit with intended…

Pleasure Activism

A framework articulated by adrienne maree brown that centers pleasure, joy, and satisfaction as essential components of social justice and liberation movements. In disability contexts, pleasure activism challenges the assumption that disabled people's lives are defined by…

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…

Pluralistic Walkthrough(also: Pluralistic Usability Walkthrough)

A group usability inspection method, introduced by Randolph Bias in 1994, in which users, developers, and usability specialists step through a task scenario together, each writing down the actions they would take at every screen before discussing as a group. It extends the…

Podcast(also: Podcasting)

An episodic, on-demand audio programme distributed over the internet, typically via RSS or proprietary platforms such as Spotify, Apple Podcasts, and BBC Sounds. Podcasts are a dominant form of long-form audio media — 92% of UK adults listen to some audio content weekly — but…

Podcast analysis(also: Podcast content analysis)

A qualitative research method that uses publicly available podcast episodes as data sources, applying thematic or content analysis to extract insights from naturalistic discussions. In accessibility research, analyzing podcasts produced by and for disabled communities offers…

Point Cloud

A set of data points in three-dimensional space, where each point represents a position on the surface of an object or environment, typically captured by depth cameras, LiDAR scanners, or photogrammetry. In accessibility applications, point clouds are used to create virtual…

Point Spread Function(also: PSF)

A mathematical description of how a single point of light is spread or blurred by an optical system such as the human eye. The point spread function characterizes the degree and pattern of distortion introduced by optical aberrations. In accessibility research, PSFs are used to…

Point of Infrastructuring(also: PoI)

A concept from Pipek and Wulf's infrastructuring theory naming the moment at which users become aware of the technology they depend on - typically when it breaks, behaves unexpectedly, or no longer supports their task - and begin to adapt, configure, or work around it. Points of…

Point of Interest(also: POI)

A point of interest (POI) is a specific location or feature in a physical environment that is relevant to a user's navigation or understanding of their surroundings. In accessible wayfinding systems for blind and low-vision users, POIs include landmarks, obstacles, entrances,…

Point-and-Click(also: Point and Click, Click Target)

A fundamental interaction paradigm in graphical user interfaces where the user moves a cursor to a target on screen and activates it by pressing a button on a pointing device such as a mouse or trackpad. Point-and-click tasks are central to GUI-based computing but present…

Point-of-Gaze(also: POG, Gaze Point, Point of Regard)

Point-of-gaze is the location on a display, scene, or object at which a user's eye is currently fixating, typically reported by an eye tracker as a stream of (x, y) screen coordinates sampled at rates between 30 and several hundred hertz. Raw point-of-gaze data is noisy and…

Point-of-Interest Techniques(also: POI Techniques)

Interaction methods in VR that allow users to select and navigate to specific points of interest in the virtual environment, designed to be accessible for people with limited mobility. These techniques typically allow users to highlight, select, and move to predetermined…

Pointer Speed(also: Mouse Gain, Cursor Speed, Mouse Speed)

An operating system setting that controls how far the cursor moves on screen relative to physical movement of the mouse or pointing device. Higher pointer speed (gain) means less physical movement is required to traverse the screen, while lower speed provides finer control but…

Pointing(also: Pointing Performance, Mouse Pointing, Cursor Pointing)

The act of moving a cursor or pointer to indicate a specific location on screen, typically to select, activate, or interact with an interface element. Pointing is a fundamental computer interaction that can be challenging for individuals with motor impairments, tremors, limited…

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…

Pointing Task(also: Target Acquisition Task, Fitts' Task)

A fundamental human-computer interaction task in which users move a cursor (via mouse, touchpad, finger, or other input device) to click or tap on a target. Pointing tasks are governed by Fitts' Law, which predicts that movement time increases with distance to the target and…

Points of interest(also: POI, Landmarks)

Specific locations in the environment that are useful or relevant to a user, such as shops, restaurants, transit stops, public buildings, and other named places. In accessible navigation for people with visual impairments, points of interest serve dual roles: they provide…

Pointwise Mutual Information(also: PMI)

A statistical measure used in natural language processing to quantify the strength of association between two words based on how much more frequently they co-occur in a corpus than would be expected by chance. PMI is calculated as the logarithm of the ratio of the observed…

Polar Motion Profile(also: PMP)

A Polar Motion Profile (PMP) is a computational technique used in sign language detection that models the quantity and distribution of motion relative to a detected face using polar coordinates. The method captures the characteristic hand and arm movements associated with…

Political/Relational Model of Disability(also: Relational Model of Disability)

A model of disability described by Alison Kafer that situates disability within sociopolitical systems, emphasizing how structures of power and interactions between people construct the experience of disability. Unlike the social model's focus on environmental barriers or the…

Polyphonic(also: Polyphony)

In music, the simultaneous combination of two or more independent melodic lines or voices. Polyphonic music is notated on multiple staves that must be read together, presenting a particular challenge for visually impaired musicians who must track multiple lines of notation…

Polysemy(also: Polysemous Words)

The property of a word having multiple related meanings or senses. For example, the word "bank" can refer to a financial institution or the edge of a river. Polysemy creates particular challenges for text simplification and accessibility tools because choosing an appropriate…

Pomodoro Technique(also: Pomodoro Method, Pomodoro Timer)

A time management method developed by Francesco Cirillo in the late 1980s that uses a timer to break work into focused intervals (typically 25 minutes) separated by short breaks (typically 5 minutes), with longer breaks after every four intervals. The technique is widely adopted…

Pop-on Captions(also: Pop-on style, Block captions)

A captioning display style in which a complete caption appears on screen as a single block, remains visible for a readable duration, and is then replaced in one transition by the next block. Pop-on captions let viewers "glance and grab" an entire sentence at once, which viewer…

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, Skeleton Tracking)

A computer vision technique that detects and tracks the positions of human body joints, hands, and facial landmarks from images or video. In accessibility contexts, pose estimation is a foundational technology for sign language recognition systems, gesture-based interfaces, and…

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…

Positionality(also: Researcher Positionality)

The practice of researchers explicitly acknowledging how their own identities, experiences, backgrounds, and power positions shape their research process, analysis, and interpretations. In disability and accessibility research, positionality statements typically disclose whether…

Positionality Statement(also: Reflexivity Statement)

A short written statement, most commonly found in qualitative research papers and accessibility HCI publications, in which authors articulate the personal, cultural, professional, and disability-related standpoints that shape their interpretation of the work. Positionality…

Positive Computing(also: Positive Technology)

A design approach articulated by Rafael Calvo and Dorian Peters (2014) and extended by Riva, Gaggioli and colleagues that intentionally orients information and communication technology toward supporting psychological wellbeing, human flourishing, and positive emotion — rather…

Positive Design(also: Design for Subjective Well-Being)

A design framework, articulated by Desmet and Pohlmeyer, that explicitly targets human flourishing by attending to three components of subjective well-being: pleasure (positive affect in the moment), personal significance (pursuit of meaningful goals), and virtue (acting in line…

Post-Exertion Malaise(also: PEM, Post-Exertional Malaise, Crash)

A disproportionate worsening of symptoms following physical, cognitive, or emotional exertion that would not cause comparable effects in a healthy person. Post-exertion malaise is a hallmark symptom of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and occurs in…

Post-Modern Model of Disability(also: Postmodern Model, Critical Disability Model)

A framework for understanding disability that integrates aspects of both the medical and social models, recognizing that both physiological factors and social barriers contribute to the experience of disability. Unlike the medical model (which locates disability in the…