Glossary

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Parameter-Efficient Fine-Tuning(also: PEFT, Lightweight Fine-Tuning)

Parameter-efficient fine-tuning is a family of techniques (LoRA, adapters, prefix tuning, prompt tuning) that adapt a large pretrained model to a new task or domain by updating only a small fraction of its parameters - typically under 1% - while freezing the rest. This…

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…

Paraplegia

A condition resulting from injury to the thoracic, lumbar, or sacral segments of the spinal cord, causing partial or complete loss of motor function and sensation in the legs, pelvis, and trunk while arm and hand function is preserved. People with paraplegia can typically use…

Parasocial Relationship(also: Parasocial Tie, Parasocial Interaction)

A parasocial relationship is a one-sided emotional bond that a media audience forms with a performer, creator, or online personality — the viewer feels a sense of friendship, loyalty, and familiarity despite no reciprocal awareness. In accessibility contexts, parasocial ties are…

Paratransit(also: Demand-responsive transit, Dial-a-ride)

A flexible, on-demand public transportation service that provides rides to people with disabilities who are unable to use fixed-route bus or rail systems. In the United States, the Americans with Disabilities Act requires transit agencies to offer complementary paratransit…

Parcel Locker(also: Package Locker, Smart Locker, Delivery Locker)

A self-service pickup cabinet where e-commerce parcels are deposited by couriers and retrieved by recipients using a code, QR scan, or mobile-app unlock. Parcel lockers are increasingly mandatory in apartment buildings and urban fulfilment networks. Accessibility barriers are…

Parents with Visual Impairments(also: PVI, Blind Parents, Visually Impaired Parents)

Parents with visual impairments (PVI) are blind or low-vision adults raising children, who are often sighted. PVI face distinctive parenting challenges that go beyond individual functional compensation: supporting children's visually-driven exploration (pointing, gaze, shared…

Paresis(also: Partial Paralysis)

A partial loss of voluntary muscle movement, distinguished from full paralysis (plegia). Paresis can affect a single limb (monoparesis), one side of the body (hemiparesis), or all four limbs (tetraparesis), and may result from stroke, cerebral palsy, spinal cord injury, or…

Pareto Principle(also: 80/20 Rule, Law of the Vital Few)

The empirical observation, named after economist Vilfredo Pareto, that in many systems roughly 80% of effects come from 20% of causes. In crowdsourcing and volunteer communities, the principle predicts that a small number of top contributors produce the majority of output, while…

Parkinson's Disease(also: PD)

A progressive neurodegenerative disorder affecting movement, including tremor, rigidity, slowness of movement, and balance problems. Parkinson's disease can also significantly affect speech (causing quiet, monotone, or slurred speech), facial expression, and fine motor control.…

Parkinsonian Tremor(also: Rest Tremor, Parkinson Tremor)

Parkinsonian tremor is an involuntary, rhythmic shaking that occurs primarily at rest and is associated with Parkinson's disease. It is caused by the reciprocal activation of antagonistic muscle groups and typically has a frequency of 4-6 Hz with a harmonic frequency…

Paro(also: Paro Robot, Paro Seal)

A socially assistive robot shaped like a baby harp seal, developed by Japan's National Institute of Advanced Industrial Science and Technology, designed to provide companionship and therapeutic engagement for older adults, particularly those with dementia. Paro responds to…

Part of Speech(also: POS, Word Class, POS Tag)

A grammatical category assigned to each word (or, in signed languages, each sign) in a sentence — such as noun, verb, adjective, adverb, pronoun, preposition, or conjunction. Automatic part-of-speech tagging is a foundational step in natural language processing pipelines. In…

Part-of-Speech(also: POS, Word Class, Lexical Category)

The grammatical category of a word — noun, verb, adjective, adverb, preposition, pronoun, conjunction, determiner, and so on. Part-of-speech labels are the basic output of part-of-speech tagging and a foundational input to many accessibility NLP pipelines: readability…

Part-of-Speech Tagging(also: POS Tagging, Grammatical Tagging)

Part-of-speech tagging is the natural-language-processing task of labelling each word in a text with its grammatical category — noun, verb, adjective, and so on — using context from surrounding words. Classical approaches use hidden Markov models with the Viterbi algorithm;…

Partial Automation(also: Adaptive Automation)

An accessibility technique in digital games and interactive systems where the system automatically performs actions or controls mechanics that a user cannot execute due to a disability, while leaving the user in control of all mechanics they can perform. For example, in a…

Partial Trisomy 9p(also: 9p Duplication Syndrome, Rethore Syndrome)

A rare chromosomal condition in which a portion of the short arm of chromosome 9 is present in triplicate rather than in duplicate. The condition is associated with intellectual disability, distinctive craniofacial features, developmental delay, and in many cases co-occurring…

Partial disclosure(also: Curated disclosure, Selective information sharing)

A disclosure strategy in which individuals share some information about their disability or neurodivergence while withholding specific details, often framing their needs in more socially accepted terms. For example, a neurodivergent worker might describe needing a quiet…

Participant Recruitment(also: Research Recruitment, Subject Recruitment)

The process of identifying, inviting, and enrolling individuals to participate in research studies. In accessibility research, participant recruitment presents unique challenges including ensuring intersectional representation of disability communities, avoiding overburdening…

Participant Verification(also: Eligibility Verification, Screening Verification)

The process of confirming that research participants genuinely meet a study's eligibility criteria, particularly regarding disability status. Verification is complicated by multiple factors: different models of disability define disability differently; online and remote…

Participant pool(also: User pool, Research panel, Participant registry)

A pre-established database of individuals who have expressed willingness to participate in research studies, maintained with demographic information, contact details, and often cognitive or ability assessments. In accessibility research, dedicated participant pools address the…

Participant pool bias(also: Sampling bias, Recruitment bias)

Systematic distortion in research findings caused by the demographic characteristics and backgrounds of study participants, rather than by the technology or intervention being evaluated. In accessibility research, participant pool bias is especially consequential because…

Participant-led research(also: User-led research)

A research methodology in which participants — particularly those from marginalized or underrepresented groups — take an active role in directing the research process, shaping study protocols, and determining what aspects of a system or experience are most important to…

Participatory AI(also: Community-Centered AI, Participatory Machine Learning)

An approach to artificial intelligence development that actively involves the communities affected by AI systems in defining problems, setting priorities, designing solutions, collecting data, evaluating outcomes, and governing deployment. Participatory AI goes beyond…

Participatory Action Research(also: PAR, Action Research)

A collaborative research methodology that involves participants as co-researchers in identifying problems, designing solutions, and implementing changes. In accessibility research, PAR ensures people with disabilities actively shape study design, data collection, and analysis…

Participatory Captioning

A framework proposed by Nguyen et al. (2026) that characterises social media video captioning as a collaborative, community-sustained infrastructure co-produced by viewers, creators, and platforms — rather than a top-down accessibility feature delivered unilaterally.…

Participatory Design(also: PD, Co-Design Process)

A design approach originating in Scandinavian workplace democracy that involves end users as active, equal partners in the design process, not merely as research subjects or consultants. In accessibility, participatory design ensures that people with disabilities contribute…

Participatory Design(also: Co-Design, Cooperative Design, PD)

A design methodology that actively involves end users as partners in the design process rather than passive subjects of user testing. In accessibility contexts, participatory design is particularly important because failing to consider user opinions early in design is a major…

Participatory Design(also: PD, Cooperative Design, Scandinavian Design)

A design approach originating in Scandinavian workplace democracy movements that emphasizes the direct involvement of people in the design of technologies and systems that affect them. Participatory design treats users as experts in their own experiences and gives them genuine…

Participatory Design with Proxies(also: PDwP, Proxy Design)

A variation of participatory design in which people who are familiar with target users or who closely resemble them are included in the design process as proxy participants. Proxies — such as parents, teachers, caregivers, or Speech-Language Pathologists — provide domain…

Participatory Evaluation(also: PE)

A research approach in which the people affected by a program, technology, or intervention are actively involved in evaluating it, rather than being passive subjects of assessment. In accessibility research, participatory evaluation means disabled people help define evaluation…

Participatory Research(also: Participatory Design Research, Participatory Action Research)

Research methodologies that actively involve the communities being studied as partners in the research process, from defining research questions to collecting data to interpreting findings. In accessibility research, participatory approaches are essential for ensuring that…

Participatory Speculative Design(also: PSD, Social Dreaming)

A design research approach that combines speculative design — imagining alternative futures and artifacts that do not yet exist — with participatory methods that position community members, particularly those historically excluded from technology design, as co-authors of those…

Participatory design(also: Co-design, PD, Cooperative design)

A design methodology originating from Scandinavian workplace practices in the 1970s in which end users, stakeholders, and designers collaborate as equal partners throughout the design process. In accessibility, participatory design is essential for ensuring that products and…

Particle Filtering(also: Sequential Monte Carlo, Particle Filter)

Particle filtering is a probabilistic localization technique that estimates a user's position by maintaining a cloud of weighted "particles," each representing a possible location. As new sensor data arrives—from GPS, inertial sensors, or other sources—particles are updated,…

Particle filter(also: Sequential Monte Carlo, Monte Carlo localization)

A probabilistic algorithm that estimates a user's position by maintaining a set of weighted hypothetical locations (particles) and updating them based on sensor observations such as Bluetooth beacon signal strengths. In indoor navigation for people with visual impairments,…

Partner Training(also: Communication Partner Training, Interlocutor Training)

Education and coaching provided to the communication partners of AAC users to help them interact more effectively and supportively. Partner training covers strategies like allowing adequate time for responses, recognizing non-verbal and device-mediated communication cues,…

Passing(also: Passing as non-disabled, Neurotypical passing)

The act of concealing one's disability or neurodivergence to be perceived as non-disabled or neurotypical by others. Passing can be a deliberate strategy to avoid stigma, discrimination, or unwanted attention, or it may occur by default when a disability is not visible. While…

Passive Accessibility Sensing(also: Automatic Barrier Detection, Breadcrumb Sensing)

A data collection approach that uses smartphone sensors (GPS, accelerometers, gyroscopes) to automatically detect potential accessibility barriers in the physical environment without requiring active user input. By analysing patterns in pedestrian movement data — such as…

Passive Exploration(also: System-Directed Presentation)

An interaction paradigm in non-visual interfaces where a complete representation of information is presented to the user all at once, rather than being discovered through user-directed navigation. In the context of accessible graphics and data visualisation, passive exploration…

Passive Haptic Feedback(also: Passive tactile feedback)

Tactile information provided to a user by the inherent physical properties of a device or interface, without any active actuation. Examples include the raised bezel around a touch screen, the tactile bump on the F and J keys of a keyboard, a notched dial, or the edge of a…

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…

Paternalism(also: Paternalistic Approach)

The practice of making decisions for others based on the assumption that one knows what is best for them, without adequately consulting or empowering them to make their own choices. In disability contexts, paternalism manifests when parents, professionals, researchers, or…

Path Integration

A cognitive navigation process in which a person tracks their position relative to a starting point by continuously monitoring their movements — including direction changes, distance traveled, and turns taken. People who are blind rely heavily on path integration when navigating…

Patient Portal(also: Electronic Health Portal, Health Portal)

A secure online platform that gives patients access to their personal health information, such as medical records, lab results, medication lists, and appointment summaries. Patient portals are intended to improve patient engagement and health management, but they often present…

Pattern Glare

A visual perceptual phenomenon where repeated striped or lined patterns cause discomfort, headaches, eyestrain, or visual distortions such as flickering, shimmering, or apparent movement. Pattern glare particularly affects people with dyslexia, epilepsy, and migraine, and can be…

Pattern Recognition

A branch of machine learning and artificial intelligence focused on identifying regularities, patterns, and structures in data such as images, sounds, or sensor readings. In accessibility, pattern recognition is fundamental to technologies like sign language recognition systems…