Glossary

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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…

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