Glossary

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PICTIVE(also: Plastic Interface for Collaborative Technology Initiatives through Video Exploration)

PICTIVE is a participatory paper-prototyping technique introduced by Michael Muller at CHI 1991, in which end users and designers jointly build low-fidelity interface prototypes using pre-cut paper UI elements (buttons, menus, text fields, icons), sticky notes, pens, and tape,…

POMDP(also: Partially Observable Markov Decision Process)

A Partially Observable Markov Decision Process (POMDP) is a mathematical framework for modelling decision-making in situations where an agent cannot fully observe the state of its environment. In accessibility research, POMDPs are used to model how people with visual impairments…

PRISMA(also: Preferred Reporting Items for Systematic Reviews and Meta-Analyses)

A standardized methodology and reporting guideline for conducting systematic literature reviews and meta-analyses. PRISMA provides a structured framework including a checklist and flow diagram that documents how studies are identified, screened, assessed for eligibility, and…

PRISMA-ScR(also: PRISMA Extension for Scoping Reviews)

PRISMA-ScR is the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews - a 20-item checklist and flow diagram that standardises how scoping reviews are reported. It adapts the PRISMA framework (designed for systematic reviews) to the…

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;…

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 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 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…

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 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…

Persona Design(also: Design Personas, User Personas)

A user-centered design technique in which designers create fictional but grounded profiles of representative users — demographics, goals, context, pain points — to guide design decisions when direct user involvement is limited. In accessibility and HCI co-design workshops,…

Personal Data Externalization(also: Data Externalization)

The process of representing internal experiences — thoughts, emotions, behaviours, bodily states — in some external medium such as a drawing, written word list, spreadsheet, physical artefact, or tracking log. Drawing on Larkin and Simon's distinction between internal and…

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…

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…

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…

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…

Postcolonial Computing

A critical framework that examines how technology design and adoption can perpetuate subtle dimensions of coloniality, under-represent certain regions such as the Global South and Indigenous societies, and marginalize their cultures and practices. In accessibility, postcolonial…

Power Spectral Density(also: PSD, Power Spectrum)

Power spectral density describes how the power of a time-varying signal is distributed across frequency components. It is a foundational tool in signal processing and shows up repeatedly in accessibility technology: in EMG-based input devices, PSD analysis of electrode signals…

PrEmo(also: Product Emotion Measurement Instrument)

A non-verbal self-report tool for measuring emotional responses, developed by Pieter Desmet. PrEmo presents users with 14 cartoon-like icons representing seven positive emotions (joy, admiration, pride, hope, satisfaction, fascination, desire) and seven negative emotions…

Practice-based Research(also: PbR)

A research approach, associated with Candy and Edmonds, in which creative practice itself is the vehicle for original inquiry and knowledge generation. Research questions arise from and are resolved through the making and performance of works, with tacit and embodied knowledge…

Probabilistic Sampling(also: Random Sampling, Statistical Sampling)

A sampling method in which every member of a population has a known, non-zero probability of being selected for the sample. In accessibility evaluation, probabilistic sampling of web pages allows auditors to make statistically valid generalisations about the overall…

Procedural task analysis(also: Task decomposition, Step-by-step analysis)

A method of breaking down complex tasks into sequential, discrete steps to understand user workflows and identify points of difficulty. In accessibility contexts, procedural task analysis reveals where users with cognitive, sensory, or motor impairments encounter barriers — such…

Prolific

An online participant recruitment platform used in academic research that allows researchers to screen and recruit participants based on demographic criteria including disability status. Prolific and similar platforms (such as Amazon Mechanical Turk) have been increasingly used…

Prototyping(also: Prototype)

The iterative creation of tangible, interactive representations of a design - ranging from paper sketches and cardboard mock-ups to functional software builds - used to explore ideas, elicit feedback, and test assumptions before committing to a final product. In accessibility…

Provocation (HCI)(also: Design provocation, Provotype)

In human-computer interaction, a designed artifact whose purpose is to unsettle assumptions, provoke debate, or surface hidden values rather than to solve a defined problem. Provocations draw on traditions of critical design (Dunne and Raby), adversarial design (DiSalvo),…

Proxy Feedback(also: Proxy User Testing, Surrogate Feedback)

A user research method in which feedback on designs or prototypes is gathered from people who are close to the target users — such as carers, therapists, family members, or support workers — rather than from the users themselves. This approach is used when direct communication…

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…

Psycholinguistics

The scientific study of the cognitive and neural processes that underlie the production, comprehension, and acquisition of language. Psycholinguistic research measures phenomena such as reading and signing rate, comprehension under time pressure, lexical access, and the role of…

Psychometric Evaluation(also: Psychometric Validation, Psychometric Analysis)

The process of assessing whether a measurement instrument (such as a questionnaire or survey) possesses desirable statistical properties including validity, reliability, and consistency. In accessibility and usability research, psychometric evaluation is used to determine…

Psychometric Test(also: Psychometric Assessment, Psychometric Evaluation)

A standardised measurement instrument designed to assess an individual's cognitive abilities, motor skills, perceptual speed, or other psychological attributes. In accessibility research and usability evaluation, psychometric tests such as the Mini-Mental State Examination…

Psychomotor testing(also: Psychomotor assessment, Motor performance testing)

The measurement of cognitive-motor integration — how quickly and accurately a person can translate mental intentions into physical actions such as reaching, pointing, grasping, or tapping. Psychomotor tests assess reaction time, movement speed, accuracy, coordination, and…

Psychophysics

Psychophysics is the scientific study of the quantitative relationship between physical stimuli and the sensations and perceptions they produce. Founded in the 19th century, it uses rigorous experimental methods to measure how humans detect, discriminate, and scale sensory…

Pupillometry(also: Pupil Dilation Measurement)

A psychophysiological measurement technique that tracks changes in pupil diameter as an objective indicator of cognitive workload, mental effort, and emotional arousal. In accessibility research, pupillometry provides a non-invasive way to assess how demanding an interface or…

Purposive Sampling(also: Purposeful Sampling, Judgment Sampling)

A non-probability sampling method in which researchers deliberately select participants based on specific characteristics relevant to the research questions. In accessibility research, purposive sampling is commonly used to recruit participants with particular disabilities,…

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