Glossary

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Automatic speech recognition(also: ASR, Speech-to-text, Voice recognition)

Technology that converts spoken language into text using machine learning and signal processing. ASR powers live captioning, voice assistants, and dictation software, making it a key accessibility technology for deaf and hard of hearing users who benefit from real-time captions.…

Blendshape(also: Morph Target, Shape Key)

A 3D animation technique that defines specific facial configurations (such as a smile, raised eyebrow, or open mouth) as target shapes, which can be blended together at varying intensities to create complex facial expressions. In sign language avatar systems, blendshape…

Block-Based Programming(also: Visual Block Programming, Block Coding, Blocks-Based Programming)

A programming paradigm where users create code by selecting and connecting visual blocks that snap together like puzzle pieces, rather than typing text-based syntax. Each block represents a programming construct such as a loop, conditional, variable assignment, or function call.…

Bridge

In the Shlaer-Mellor software analysis method, a bridge describes the relationships between two independently modelled problem domains. For example, the abstract concept of a menu of selectable options in a user interface has counterparts in concrete graphical user interface…

Collision Detection(also: Contact Detection, Intersection Testing)

In virtual reality and haptic systems, collision detection is the computational process of determining when virtual objects come into contact with each other or with a user's virtual representation (such as a virtual hand or cane). When a collision is detected, the system can…

Context-Free Grammar(also: CFG, Formal Grammar)

A formal system for defining the syntactic rules of a language, consisting of a set of production rules that describe how symbols can be combined to form valid expressions. In accessibility and assistive technology, context-free grammars are significant because they can be used…

Directed graph(also: Digraph)

A mathematical structure consisting of nodes connected by edges that have a defined direction — the connection from A to B is distinct from the connection from B to A. Web navigation is modelled as a directed graph: a hyperlink from page A to page B does not imply a link back…

Finite State Machine(also: FSM, State Machine)

A computational model that can exist in exactly one of a finite number of states at any given time, transitioning between states in response to specific inputs or events. In assistive technology, finite state machines are used to translate simple binary inputs (such as muscle…

Game theory

A branch of applied mathematics that models strategic decision making in competitive or cooperative environments. In accessibility research, game theory has been applied to model the allocation of scarce resources in adaptive user interfaces — for example, when multiple content…

Graph theory

A branch of mathematics that studies the relationships and connections between objects in an abstract sense. Graphs consist of nodes connected by edges, and can model a wide range of structures: roads connecting at intersections, books arranged by subject in a library, or web…

Hybrid automaton(also: Hybrid state machine)

A computational model that combines discrete state transitions with continuous dynamics, used in interactive systems to govern object behaviours based on multiple users's simultaneous inputs. In collaborative virtual environments for autism intervention, hybrid automata control…

Intelligent agent(also: Software agent, Autonomous agent)

An autonomous computer program or algorithm that acts on behalf of another entity, typically a user. Intelligent agents work to a set of rules that may evolve over time based on experience. In accessibility, intelligent agents can observe user behaviour and adapt interfaces…

Inverse Kinematics(also: IK)

A mathematical technique used in computer animation and robotics to calculate the joint positions needed to place an end effector (such as a hand or foot) at a desired position in space. In signing avatar applications, inverse kinematics allows natural arm and body posture to be…

Late binding

A software engineering concept where decisions about how components connect are deferred until runtime rather than being fixed at design time or compile time. In user interface design, late binding refers to the practice of keeping the abstract description of an interface…

Mark

An elementary entity capable of perception within a spatial substrate. In the visual design space, marks include points, lines, circles, and areas — the basic building blocks from which all visual representations are composed. A bar chart is constructed from rectangular marks…

Model-View-Controller(also: MVC)

A software architectural pattern that separates an application into three interconnected components: the Model (data and business logic), the View (presentation and user interface), and the Controller (input handling and mediation between Model and View). MVC is significant in…

Object-oriented analysis and design(also: OOA, OOD, OOAD)

A software engineering methodology that describes complex systems in terms of related, cooperating entities (objects) rather than as sequences of procedures. For example, a user interface can be modelled as relationships between content objects, presentation objects, and…

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,…

Reification

The process of making concrete that which is abstract. A photograph is a reification of a moment in time and place, with all the selectivity and distortion that the lens and framing impose. A web page is a reification of underlying data and semantic relationships, rendered…

Semantic decomposition

An analysis method that models a system as a hierarchy of ontological dependencies based on meaning and conceptual relationships, rather than breaking it down by functional tasks. In user interface design, semantic decomposition contrasts with traditional task-based…

Simultaneous Localization and Mapping(also: SLAM)

A foundational robotics technique in which a robot constructs a map of an unknown environment while simultaneously estimating its own pose within that map. SLAM combines sensor input (typically LiDAR, depth cameras, or monocular vision) with probabilistic state estimation…

Spatial substrate

A framework describing the orientation and positioning of information within a design space, using axes and a coordinate system appropriate to how a user perceives content in that space. In the visual design space, a spatial substrate is typically a two-dimensional plane (a…

Temporal encoding

The representation of information through change over time within a spatial substrate. In the visual design space, temporal encoding corresponds to animation — a point or shape moving, appearing, or changing on screen. In the sonic design space, temporal encoding is the primary…

Turing Test(also: Imitation Game)

The Turing Test, proposed by Alan Turing in 1950, is a thought experiment for assessing whether a machine's conversational behaviour is indistinguishable from that of a human. A human evaluator engages in a text-based exchange with both a human and a machine and must decide…

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