Glossary

Search results

Peak Velocity

The maximum speed reached by a cursor or limb during a directed movement toward a target. In human-computer interaction research, peak velocity is a key metric for understanding pointing performance, typically occurring in the first quarter of a movement. Peak velocity decreases…

Pebbling

A neurodivergent-coined term for the practice of expressing and receiving affection by sharing small tokens — often memes, short videos, articles, or other links — with loved ones. The term references the courtship behavior of penguins, who offer pebbles to their partners.…

Pedagogic Culture(also: Pedagogical Culture)

The ecosystem of shared debate, investigation, evaluation, and knowledge exchange that supports excellence in teaching and learning within a discipline. A healthy pedagogic culture involves systematic research into how subjects are taught, cross-citation and dialogue among…

Pedagogical Content Knowledge(also: PCK)

A concept from educational research referring to the intersection between a teacher's general pedagogical expertise (how to teach) and the specific content knowledge of their discipline (what to teach). In accessibility education, PCK encompasses understanding not only the…

Pedestrian Accessibility(also: Sidewalk Accessibility, Walkability)

The degree to which outdoor pedestrian infrastructure — sidewalks, crosswalks, curb cuts, ramps, stairs, and pathways — enables people with diverse mobility needs to travel safely and independently on foot or using mobility devices. Pedestrian accessibility is affected by…

Pedestrian Crossing(also: Crosswalk, Zebra crossing, Pedestrian crosswalk)

A designated location on a road where pedestrians have legal priority, guidance, or protection to cross, typically marked by paint (zebra or ladder stripes), signs, or signal-controlled infrastructure. Pedestrian crossings range from unmarked mid-block crossings through…

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(also: Pedestrian Wayfinding, On-Foot Navigation)

Pedestrian navigation refers to wayfinding and route-following on foot in outdoor environments, including sidewalks, crosswalks, public transit access points, and shared streets. For blind and low vision users, people with cognitive disabilities, and wheelchair users, the…

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…

Pedestrian Safety(also: Walking safety, Vulnerable road user safety)

The field and practice of protecting people who walk — including those with disabilities, older adults, and children — from injury and death in road traffic environments. Pedestrian safety encompasses road design (crossings, curb ramps, accessible pedestrian signals, raised…

Pedestrian dead reckoning(also: PDR, Inertial navigation, Step-and-heading)

A localization technique that estimates a person's position by counting their steps (to determine distance) and detecting turns (to determine heading changes) from a known starting point, using inertial sensors in a smartphone or wearable device. For blind indoor navigation,…

Pediatric Rehabilitation(also: Children's Rehabilitation, Paediatric Rehabilitation)

A specialized area of rehabilitation medicine focused on children and adolescents with disabilities, developmental delays, or injuries. Unlike adult rehabilitation which typically aims to restore lost function, pediatric rehabilitation focuses on developing new skills, fostering…

Peer Culture

Peer culture is the body of shared understandings, values, social norms, communication practices, and play conventions that children co-construct among themselves through daily interaction - distinct from the adult culture that surrounds them. It defines who can join play, how…

Peer Feedback(also: Peer Review, Peer Assessment)

The process of learners observing and providing constructive feedback to each other during learning activities. In collaborative sign language learning, peer feedback enables real-time correction and coaching — players can observe each other's signing and identify mistakes…

Peer Mentoring(also: Peer Support, Peer Tutoring)

A support relationship where individuals with shared experiences provide guidance, emotional support, and practical assistance to one another, typically in informal or semi-structured settings. For ADHD students in higher education, peer mentoring from other ADHD students is…

Peer Note-Taking Program(also: PNTP, Peer Note-Taker Program, Note-Taking Assistance Program)

A disability support service offered by higher education institutions in which peer students (peer note-takers or PNTs) assist students with disabilities (SWDs) by transcribing lecture notes during class or sharing their own notes afterward. PNTPs are widely adopted as academic…

Peer Support(also: Peer-to-Peer Support, Peer Mentoring)

A form of mutual assistance where people with shared experiences or conditions help each other by sharing knowledge, practical advice, and emotional support. In accessibility contexts, peer support communities are particularly valuable for disabled users learning complex…

Pelli-Robson Chart(also: Pelli-Robson Contrast Sensitivity Chart)

The Pelli-Robson chart is a clinical tool used to measure contrast sensitivity — the ability to detect objects at low-to-moderate contrast levels. The chart consists of a series of letter-charts composed of different contrasts, mapping a contrast-sensitivity function for the…

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 Input(also: Stylus Input, Pen-Based Input)

An input method using a pen or stylus to interact with a computing device, typically through direct manipulation on a touchscreen or digitizer. Pen input offers advantages for users with certain motor impairments: compared to mice, pens allow users to leverage hand-eye…

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 Who Stutter(also: PWS, Person Who Stutters, Adults Who Stutter)

An identity-first and community-preferred term for people who experience stuttering, a neurodevelopmental condition involving involuntary speech disfluencies such as blocks, prolongations, and repetitions. PWS affects roughly 1% of the global population. Community usage (PWS,…

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…

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…

Pepper(also: Pepper Robot)

A 120 cm semi-humanoid social robot developed by SoftBank Robotics (originally with Aldebaran Robotics), featuring articulated arms with 20 degrees of freedom, LED eyes capable of gaze behaviours, an animated face, and a chest-mounted tablet for touch interaction. Pepper is…

Perceivability(also: Perceivable)

The quality of information or interface elements being detectable through one or more senses — sight, hearing, or touch. Perceivability is the first principle of WCAG 2.0 and requires that information and user interface components be presentable to users in ways they can…

Perceived Accessibility(also: Subjective Accessibility, Accessibility-in-Use)

Perceived accessibility refers to the subjective quality by which users experience the accessibility of a website or application, as opposed to its objective compliance with accessibility standards. Research has shown that guideline-conformant websites can still be perceived as…

Perceived Urgency(also: Alert urgency, Urgency perception)

The subjective sense of immediacy or threat conveyed by an alert, shaped by parameters such as pulse rate, inter-pulse interval, pitch, loudness, and — for tactile signals — vibration intensity and pattern duration. Research on aircraft alarms, hospital alarms, and driver…

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 Analysis(also: Perceptual Judgment, Auditory-Perceptual Analysis)

A method of evaluating speech, voice, or other sounds based on a human listener's subjective auditory impressions rather than instrumental measurement. In clinical speech-language pathology, perceptual analysis is used to categorize vocalizations, rate voice quality, or assess…

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 Congruence(also: Perceptually Congruent Structure)

A design principle for accessible representations that requires the structure of a non-visual interface (such as a screen reader navigation tree) to mirror the visual structure of the original graphical representation. A perceptually congruent screen reader structure preserves…

Perceptual Cycle(also: Perceptual Response Time, Perceptual Processing)

In the Model Human Processor framework, the perceptual cycle is the time required for a person to perceive and register a stimulus from their environment, such as seeing a visual change on screen. The perceptual cycle time for both able-bodied and motor-impaired users is…

Perceptual Gap

A design failure identified by Choudhury (2026) in which an AI system's explanation is delivered through exactly the sensory channel that its user cannot access. For example, a Grad-CAM heat map overlaid on an image tells a blind user where the model looked but cannot be seen by…

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 Hashing(also: Image Hashing, pHash)

A technique that generates a compact fingerprint (hash) of an image based on its visual content rather than its raw data. Unlike cryptographic hashes that change completely with any modification, perceptual hashes produce similar values for visually similar images, allowing…

Perceptual Integration(also: Perceptual Binding)

The process by which the brain combines information arriving through different sensory channels — vision, hearing, touch, proprioception — into a single coherent percept of an object or event. Perceptual integration depends on temporal synchrony (cues arriving within roughly 100…

Perceptual Learning(also: Visual Perceptual Learning, PL)

A long-studied phenomenon in vision science in which repeated exposure to, or training on, specific perceptual features — color, orientation, spatial location, shape — produces durable improvements in a person’s ability to detect and discriminate those features. Perceptual…

Perceptual Linear Prediction(also: PLP, PLP Coefficients)

Perceptual Linear Prediction (PLP) is an acoustic feature extraction technique used in speech processing that models human auditory perception. PLP analysis applies psychoacoustic principles including critical band frequency resolution, equal-loudness pre-emphasis, and…

Perceptual Span(also: Reading Span, Visual Span)

The area of text around a fixation point from which useful information can be extracted during reading. Research using eye-tracking has shown that skilled deaf readers have a larger perceptual span than hearing readers — up to 18 letter spaces compared to 14 for hearing readers…

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…

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…

Perceptualisation(also: Perceptualization)

A multi-sensory display of abstract information, inferred by Nesbitt to be a fundamentally human quality. Where visualisation presents abstract data through the visual design space (charts, graphs, maps), perceptualisation extends this to all sensory channels — sonic, haptic,…

Perfect Pitch(also: Absolute Pitch, AP)

The innate ability to identify or reproduce musical pitches without the aid of a reference note. People with perfect pitch can recognize and name any musical note by its pitch alone. For blind and low vision musicians, perfect pitch can be a significant advantage, serving as a…

Perinatal depression(also: PND, Perinatal mood disorder)

Perinatal depression (PND) refers to major depressive episodes that occur during pregnancy (antenatal depression) or in the weeks following childbirth (postpartum depression). It affects up to 10% of individuals during the perinatal period and carries significant societal costs,…

Peripersonal Space(also: Near space, Reaching space)

The area immediately surrounding the body that is within arm's reach, typically extending about 60-70 cm from the body. Peripersonal space is significant in accessibility because blind and visually impaired children often have delayed development of spatial awareness within this…

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…

Peripheral Neuropathy(also: Neuropathy)

Peripheral neuropathy is a condition resulting from damage to the peripheral nerves, which carry signals between the brain, spinal cord, and the rest of the body. Symptoms typically include numbness, tingling, weakness, and pain, most commonly in the hands and feet. For…