Glossary

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Programming by Example(also: PBE, Programming by Demonstration)

A technique in end-user programming where a system infers a generalizable program from concrete examples provided by the user, rather than requiring the user to write code directly. In accessibility contexts, programming by example has been used to enable nonprogrammers to…

Proteus Effect

The Proteus Effect is a phenomenon, first described by Yee and Bailenson (2007), in which the appearance of a person's avatar influences how they think, behave and interact in virtual or augmented environments. For example, users assigned taller or more attractive avatars tend…

Proxemics(also: Interpersonal distance, Personal space)

The study of how people use and perceive physical space in social interactions, originally defined by anthropologist Edward T. Hall in 1966. Hall identified four distance zones: intimate (0–45 cm), personal (45 cm–1.2 m), social (1.2–3.6 m), and public (beyond 3.6 m). In…

RESOLV Icons(also: Representational Enumerated Semi-transparent Overlaid Labels for Voice)

A visual disambiguation technique for voice interfaces where semi-transparent numbered labels are overlaid on screen elements that match an ambiguous voice command. When a user speaks a command that could refer to multiple targets, RESOLV icons appear next to each matching…

Relaxed Scoping(also: Flexible Scoping)

A voice navigation strategy that allows users to name any target on the screen directly without first navigating through a hierarchy. Relaxed scoping prioritizes efficiency by enabling single-command access to interface elements, but it increases the potential for target…

Reminiscence therapy(also: Reminiscence, Life review therapy, Memory sharing)

A therapeutic intervention widely used with older adults and people with dementia that involves the structured recall and sharing of personal memories and life experiences, often supported by prompts such as photographs, music, objects, or — increasingly — digital technologies.…

Reverse Privacy Paradox

The reverse privacy paradox is a pattern, described by Zhang and colleagues in research on LLM-based conversational agents, in which users appear to disregard privacy concerns in the moment of use while still recognising those concerns exist and being willing to adopt…

Rigid Scoping

A voice navigation strategy that requires users to explicitly navigate through a hierarchical structure before issuing commands to specific targets. In rigid scoping, the user must first select a container or menu level, then name items within that scope, preventing ambiguity by…

Robotic Social Attributes Scale(also: RoSAS, RoSAS-SF, Robotic Social Attributes Scale Short Form)

A validated psychometric instrument developed by Carpinella et al. (2017) that measures how people perceive the social attributes of a robot along three subscales: Warmth (how likable, friendly, and companionable the robot feels), Competence (how capable, knowledgeable, and…

Scanpath(also: Gaze Path, Eye Movement Path)

The sequence of fixations and saccades (rapid eye movements) that represent how a person visually explores an interface or document. In accessibility and usability research, scanpath analysis reveals patterns in how users process visual information, which elements attract…

Scanpath Trend Analysis(also: STA)

A method for analysing multiple eye-tracking scanpaths to identify a single representative trending path that captures the most common viewing patterns across a group of users. STA determines which visual elements of a web page are most frequently visited and in what order,…

Segmentation Problem(also: Stroke Segmentation, Input Segmentation, Gesture Segmentation)

The segmentation problem in text entry and gesture recognition refers to the challenge of determining where one input unit (such as a letter, word, or gesture) ends and the next begins when there is no explicit delimiter between successive inputs. For stylus-based systems,…

Self-Adaptive System(also: Self-Adapting System, Adaptive Interface)

A software or hardware system that automatically monitors user behaviour and adjusts its configuration or interface to better suit the user's needs without requiring explicit manual intervention. In accessibility, self-adaptive systems can detect changes in a user's motor…

Semiotic Engineering(also: Semiotics of HCI)

A theoretical framework developed by Clarisse Siqueira de Souza that views human-computer interaction as a form of designer-to-user communication mediated by the interface. In this model, the interface is not merely a tool but a message from designers to users, carrying an…

Semiotic Inspection Method(also: SIM, MIS)

An evaluation method from Semiotic Engineering theory that systematically assesses the communicability of an interactive system by examining how well the designer's intended message is conveyed through the interface. The evaluator analyzes three types of interface signs…

Sense of Presence(also: Virtual Presence, Spatial Presence)

The subjective feeling of "being there" in a virtual environment, encompassing spatial presence (feeling physically located in the virtual space), involvement (attention directed at the virtual world), and experienced realism (how lifelike the environment feels). Sense of…

Shannon Entropy(also: Information Entropy, Source Entropy)

A measure of the average uncertainty or unpredictability associated with a set of possible outcomes, defined by Claude Shannon as H = -Σ p(x) log₂ p(x), where p(x) is the probability of each outcome. In the context of interface evaluation, entropy quantifies how much uncertainty…

Simultaneous Assistance

Simultaneous assistance, described by Cynthia Bennett and Daniela Rosner, is a form of support in which help flows in multiple directions at once rather than unidirectionally from a non-disabled helper to a disabled recipient. In a simultaneous-assistance encounter, the disabled…

Situated action(also: Situated cognition, Situated practice)

A theoretical framework from sociology and HCI holding that human actions and decisions are fundamentally shaped by the specific social, material, and temporal context in which they occur, rather than being pre-planned or rule-following. In explainable AI design, situated action…

Socially Recursive Inference(also: Social Recursion)

The cognitive process by which individuals' perceptions and behaviors are shaped by what they believe others think about them or their situation. In accessibility contexts, socially recursive inference manifests when AT users are influenced by what they think non-disabled people…

Spatial Computing(also: Spatial interaction)

A paradigm of computing in which digital content is rendered and interacted with in three-dimensional physical space, typically via head-worn augmented or mixed reality devices (e.g., HoloLens, Magic Leap, Apple Vision Pro, Snap Spectacles) that track head pose, hands, eyes, and…

Spatial cognition(also: Spatial awareness, Cognitive mapping)

The mental processes involved in perceiving, storing, recalling, and using information about spatial environments — including the locations of objects, distances between them, routes through spaces, and the overall geometry of an area. Spatial cognition enables people to build…

Spatial sensitivity(also: Personal space sensitivity, Proxemic sensitivity)

Heightened awareness of and discomfort with the physical proximity of others or objects, particularly common among autistic individuals and people with anxiety or PTSD. Spatial sensitivity involves strong reactions to violations of personal space boundaries, which can extend to…

Speech Acts Theory(also: Speech Act Theory, Illocutionary Acts)

A theory from the philosophy of language, originally developed by J.L. Austin and John Searle, which holds that utterances are not just statements of fact but also actions that accomplish things — such as requesting, promising, warning, or commanding. In assistive technology and…

Speech User Interface(also: SUI, Voice User Interface, VUI)

A user interface that enables interaction with a computer or device primarily through spoken language rather than through physical input devices like keyboards, mice, or touchscreens. Speech user interfaces use speech recognition to interpret user commands and may provide…

Steering Law(also: Accot-Zhai Steering Law)

A predictive model of human movement describing the time required to navigate a cursor through a constrained path, such as a tunnel or curved corridor on screen. Proposed by Accot and Zhai as an extension of Fitts's Law, the Steering Law accounts for tasks where the user must…

Submovement(also: Movement Component, Movement Segment)

A discrete component of a larger aimed movement, separated from other submovements by pauses or changes in velocity. According to the Optimized Submovement Model from motor performance theory, a rapid aimed movement such as moving a cursor to a target consists of an initial…

Surround sound(also: Multichannel audio, 5.1 audio, 7.1 audio)

An audio reproduction technique that uses multiple speaker channels arranged around the listener to create an enveloping sound field. Common configurations include 5.1 (five speakers plus a subwoofer) and 7.1 (seven speakers plus a subwoofer), where speakers are placed at…

Tablet Input(also: Graphics Tablet, Pen Tablet, Digitizer Tablet)

An input device consisting of a flat surface that detects the position and movement of a stylus or digital pen, translating physical writing and drawing motions into digital input. Graphics tablets (such as those made by Wacom) provide an alternative to mouse input that…

Tangible User Interface(also: TUI, Physical Interface)

An interface in which users interact with digital information through physical objects and surfaces in the real world. Tangible user interfaces bridge the gap between digital and physical by giving digital data a physical form that can be grasped, moved, and manipulated. For…

Target Ambiguity(also: Command Ambiguity)

A usability problem in voice and speech-based interfaces where a user's spoken command could refer to more than one element on the screen. For example, if multiple buttons share the same label in different parts of an application, saying that label creates ambiguity about which…

Target Highlight Time(also: THT)

A performance measure used in human-computer interaction research that captures the time elapsed between when a user positions a pointer over a target and when they initiate an action on that target, such as clicking or dragging. THT reflects how quickly a user can recognize and…

Target Selection(also: Target Acquisition, Pointing)

The fundamental interaction task of moving a cursor or pointer to a specific location on screen and confirming selection, such as clicking a button or link. Target selection difficulty is affected by target size, distance to target, and user motor abilities—relationships…

Target acquisition(also: Target selection, Pointing task)

The process of moving a pointer or input device to a specific on-screen element and selecting it, such as tapping an icon, clicking a button, or choosing a menu item. Target acquisition is a fundamental interaction in graphical user interfaces, and its difficulty is influenced…

Task Analysis(also: Hierarchical Task Analysis, HTA)

A systematic method for breaking down complex activities into their component tasks, subtasks, and actions to understand how users accomplish goals when interacting with a system. In accessibility and usability evaluation, task analysis is used to identify potential barriers by…

Technology Acceptance(also: Technology Adoption, TAM)

The process by which individuals evaluate, adopt, and integrate new technology into their routines, often modeled through frameworks like the Technology Acceptance Model (TAM) which emphasizes perceived usefulness and ease of use as key predictors. For accessibility, technology…

Technology Adoption Model(also: TAM)

A theoretical framework developed by Fred Davis that explains how users come to accept and use new technology. The model proposes that perceived usefulness and perceived ease of use are the primary factors influencing technology adoption decisions. In accessibility research, TAM…

Technology Probe

A research method that deploys a simple, functional technology prototype in real-world or realistic settings to observe user interactions and gather feedback about future design possibilities. Unlike polished prototypes, technology probes are intentionally open-ended, designed…

Technology Probe

A simple, flexible technology deployed in real-world settings to gather data about user needs, preferences, and interaction patterns. Unlike polished prototypes, technology probes are intentionally open-ended and incomplete, designed to inspire users and researchers to explore…

Technology acceptance(also: User acceptance, Technology adoption)

The degree to which individuals are willing to embrace, use, and integrate a new technology into their practices, influenced by perceived usefulness, ease of use, social norms, trust, and prior experience. In accessibility contexts, technology acceptance is shaped by additional…

Text Entry(also: Text Input, Text Generation)

The process of entering text into a computer or communication device, encompassing the full range of input methods from standard keyboards to alternative approaches used in assistive technology such as on-screen keyboards, word prediction, scanning, switch-based input, eye…

Third Wave Accessibility(also: Third Wave HCI Accessibility)

An approach to accessibility that considers the full context of people's lives rather than focusing narrowly on task completion or interface design. Third wave accessibility recognizes that technology use is embedded in social, cultural, and emotional contexts, and that people…

Time Diary(also: Time Use Diary, Activity Diary)

A research methodology in which participants record their activities, experiences, or events in real time or near-real time as they occur, rather than recalling them retrospectively. In accessibility and usability research, time diaries have been used to capture frustrating…

Touch Drift(also: Finger Drift)

The displacement of a finger's contact point on a touchscreen between the initial finger-down position and the final finger-up position during a single touch interaction. Touch drift measures how far a touch "slides" from where it started to where it ended, distinct from touch…

Transfer Function(also: Mapping Function, Control-Display Gain)

A mathematical function that defines the relationship between an input signal and an output response in a control system. In assistive technology and pointer control, a transfer function determines how physical movements (such as head movements, eye gaze, or joystick input) are…

Trimodal Feedback(also: Triple-Modality Feedback)

A form of interface feedback that delivers information through three simultaneous sensory channels — typically auditory, haptic, and visual. Trimodal feedback offers the highest level of redundancy in multimodal interface design, ensuring that users can perceive system responses…

UI Agent(also: User Interface Agent, Browser Agent, AI Agent)

An AI-powered software system that can autonomously interact with graphical user interfaces on behalf of a user, performing tasks by interpreting natural language commands and translating them into interface actions such as clicking buttons, entering text, and navigating between…

Usability Engineering

A systematic, structured approach to designing and evaluating user interfaces that applies engineering principles to usability. Usability engineering involves defining measurable usability goals, conducting user analysis, iterative prototyping, and empirical testing with…

User Enactment(also: UE, Experience Prototyping)

A research method in which participants explore emerging or future technologies through simulated scenarios using physical enactment stages (mockup environments). User enactment combines brainstorming, where participants speak aloud their thoughts and decisions, with…

User Frustration(also: Computer Frustration, Technology Frustration)

The emotional response experienced by users when technology fails to meet their expectations or prevents them from completing tasks. User frustration can be caused by errors, confusing interfaces, inaccessible content, slow response times, or situations where the computer is…