Glossary

Search results

Deconvolution

A computational process that reverses the blurring effects of convolution in an optical or imaging system. In the context of visual accessibility, deconvolution is used to pre-process images displayed on a computer screen so that when viewed through an eye with known…

Decorative Image(also: Decorative Graphic, Presentational Image)

An image that serves a purely aesthetic or visual design purpose and does not convey meaningful information to the user. According to WCAG guidelines, decorative images should receive empty alt text (alt="") so that screen readers skip over them rather than announcing…

Decreased Sound Tolerance(also: DST, Sound Intolerance)

Decreased sound tolerance (DST) is an umbrella term for conditions in which everyday sounds are perceived as uncomfortably loud, threatening, or emotionally distressing. It encompasses hyperacusis (abnormal sensitivity to sound volume), misophonia (strong emotional reactions to…

Deep Learning(also: DL)

Deep learning is a subset of machine learning that uses artificial neural networks with multiple layers to learn complex patterns from large amounts of data. In accessibility contexts, deep learning powers many assistive technologies including automatic image description for…

Deep Pressure Therapy(also: DPT, Deep Pressure Stimulation, Deep Touch Pressure)

A therapeutic approach that uses firm, distributed tactile pressure — such as from weighted blankets, compression garments, or inflatable vests — to reduce anxiety, stress, and physiological arousal. Deep pressure stimulation activates the parasympathetic nervous system,…

Deepfake(also: Synthetic Media, AI-Generated Media)

AI-generated or AI-manipulated media (images, video, audio, or text) designed to convincingly depict events, people, or statements that never occurred. Deepfakes pose specific risks for people with disabilities: AI-generated fake images of disabled people have been used for…

Default Delivery Context(also: DDC)

A baseline set of device capabilities defined by the W3C Mobile Web Best Practices specification, used as a reference point for evaluating mobile web content. The Default Delivery Context specifies minimum characteristics such as a 120-pixel screen width, XHTML Basic 1.1…

Deficit Narrative(also: Deficit-Based Framing, Deficit Model)

A framing approach that characterizes disability or neurodivergence primarily in terms of what individuals lack, cannot do, or do poorly compared to a non-disabled norm. Deficit narratives are embedded in many clinical assessment tools through language that pathologizes natural…

Deficit-Based Approach(also: Deficit Model, Deficit Framing, Deficit Perspective)

An approach that focuses primarily on what individuals cannot do, what skills they lack, or what is "wrong" with them, rather than their strengths, abilities, and potential. In disability and accessibility contexts, deficit-based approaches frame disabled people through their…

Deficit-Oriented Research(also: Deficit Model, Deficit-Based Approach)

A research approach that frames its subjects primarily in terms of what they lack, cannot do, or need to have fixed, rather than recognizing their strengths, agency, and lived expertise. In disability and accessibility research, deficit-oriented approaches treat disabled bodies…

Defluffing(also: Content Defluffing, Clutter Removal)

The process of removing non-essential visual elements from a web page — such as banners, advertisements, decorative images, and sidebar content — to expose the core information content more directly to assistive technology users. In the context of web accessibility transcoding,…

Deformable Input(also: Flexible Input Surface)

An input method that uses physically flexible or pressure-sensitive surfaces that can be bent, squeezed, twisted, or otherwise deformed to generate control signals. Deformable input devices can provide accessible interaction for users with motor impairments, as they may require…

Degrees of Freedom(also: DoF, 3DoF, 6DoF)

In virtual and extended reality, degrees of freedom refers to the number of independent movement axes available to a user within a virtual environment. Three degrees of freedom (3DoF) allows rotational head tracking only — looking up/down, left/right, and tilting — which is…

Deictic Gesture(also: Pointing Gesture)

A deictic gesture is a pointing or indicating motion (typically with a finger, but also with gaze, head, or tool) that directs another person's attention to a specific referent in the shared environment. In face-to-face tutoring, deictic gestures are central to effective…

Deictic Reference(also: Deixis, Pointing Reference)

Communication that refers to something by pointing or indicating rather than describing it explicitly—words like "this," "that," "here," and "there." In face-to-face communication, deictic references typically rely on visual cues (pointing gestures, gaze direction). For people…

Deinstitutionalisation(also: Deinstitutionalization)

The process of transitioning people with disabilities — particularly intellectual disabilities and mental health conditions — from large, segregated residential institutions into community-based living arrangements with appropriate support services. Beginning in Scandinavian…

Deinstitutionalization

The process of transitioning disabled people from large, segregated residential institutions to community-based living settings, along with the development of community support services. In the United States, deinstitutionalization gained momentum in the 1950s and 1960s driven…

Delegated Agency(also: Delegated Technical Agency)

Delegated agency occurs in augmentative and alternative communication (AAC) when a close conversation partner (such as a parent or aide) acts on behalf of an augmented communicator to advance the communicator's conversational goals. This may include expanding on the…

Delegation (Human-Robot Interaction)(also: Delegation, Task delegation to robot)

In human-robot interaction, the explicit transfer of a task or decision from a human to a robot. Delegation is a form of shared control in which authority for a specific subtask — for example, asking bystanders to step aside, announcing an obstacle, or choosing a path around a…

Delivery Context

Delivery context is a term defined by the W3C Device Independence Working Group to describe the set of attributes that characterize the environment in which web content is delivered and consumed. This includes device capabilities (screen size, supported markup languages, color…

Delphi Method(also: Delphi Technique, Delphi Interview)

A structured research technique originally developed by the RAND Corporation for forecasting, in which a panel of experts participates in multiple rounds of questioning to reach consensus on a topic. In accessibility and HCI research, the Delphi method is used to gather expert…

Demand Avoidance(also: Pathological Demand Avoidance, PDA, Persistent Drive for Autonomy)

An inner resistance to perceived demands — even self-imposed ones — that can lead to inability to start, change, or complete tasks. Demand avoidance is associated with an autism profile sometimes called Pathological Demand Avoidance (PDA) in the UK, and more recently reframed by…

Demand Characteristics

Cues within a research study that signal to participants what the researcher expects or hopes to find, leading participants to adjust their behavior or responses to meet those perceived expectations. In accessibility research, demand characteristics can be especially pronounced…

Dementia(also: Major neurocognitive disorder)

An umbrella term for a group of symptoms related to progressive decline in memory, thinking, behaviour, and the ability to perform everyday activities, caused by diseases or injuries affecting the brain. Alzheimer's disease is the most common cause, accounting for 60-70% of…

Dementia

A group of progressive neurological conditions that affect memory, thinking, orientation, comprehension, language, and judgment. Alzheimer's disease is the most common form. Dementia significantly impacts how people interact with digital technology, often requiring simplified…

Dementia Advocacy(also: Dementia self-advocacy)

Dementia advocacy encompasses efforts by people living with dementia, caregivers, and allies to promote more inclusive, dignified, and rights-based understandings of dementia in public discourse, policy, and service design. Self-advocacy—where individuals with dementia share…

Dementia-Friendly(also: Dementia Friendly Community, Dementia Inclusive)

An approach to designing environments, services, programs, and communities that are accessible, supportive, and inclusive of people living with dementia. A dementia-friendly community enables people with dementia to participate in social life, access services, and maintain…

Dementia-Friendly Community(also: Dementia Friendly Community)

An approach to inclusion in which public spaces, services, programs, and technologies are designed so that people living with dementia can continue to participate as active community members - shopping, using transport, attending cultural venues, socialising - alongside their…

DementiaBank

A shared database of multimedia interactions for the study of communication in dementia, maintained as part of the TalkBank system. DementiaBank contains longitudinal recordings of people with Alzheimer's disease and matched controls performing tasks like the "cookie theft"…

Deployment Study(also: Field Deployment, In-the-Wild Study)

A research method where technology is placed in users' real-world environments for an extended period to observe natural usage patterns, adoption behaviors, and long-term experiences. Unlike controlled lab studies, deployment studies capture ecological validity by revealing how…

Depression(also: Major Depressive Disorder, Clinical Depression)

A mental health condition characterized by persistent feelings of sadness, hopelessness, and loss of interest in activities. Depression can significantly impact cognitive function, including concentration, memory, and decision-making, which affects how individuals interact with…

Depth Camera(also: Depth Sensor, RGB-D Camera, 3D Camera)

A depth camera is a device that captures both standard visual imagery and per-pixel distance information, producing a 3D representation of the scene. Technologies include structured light (projecting patterns and measuring distortion), time-of-flight (measuring how long light…

Depth Estimation(also: Monocular Depth Estimation, Depth Prediction)

The computer vision task of predicting the distance from the camera to each point in a scene, producing a depth map in which each pixel carries a distance value. Monocular depth estimation uses a single RGB image (no stereo cameras or LiDAR) and typically relies on deep learning…

Depth Perception(also: Stereopsis)

The visual ability to perceive the relative distance of objects in three-dimensional space. Depth perception relies on binocular vision and other visual cues. Reduced depth perception can affect a persons ability to navigate physical environments safely, judge distances, and…

Depth Sensing(also: Depth Perception (computer vision), 3D Sensing)

The ability of a sensor or system to measure the distance from itself to objects in the scene, producing a depth map or point cloud rather than a flat image. Common approaches include stereo vision (triangulating between two cameras), structured light (projecting a known…

Depth Sensor(also: Depth Camera, RGB-D Sensor, 3D Sensor)

A device that captures three-dimensional depth information about a scene in addition to standard two-dimensional imagery. Depth sensors measure the distance from the camera to objects in the environment, enabling more accurate detection and tracking of faces, hands, and body…

Description Logic(also: DL, Description Logics)

A family of formal knowledge representation languages used as the mathematical foundation for ontology languages like OWL. Description logics describe a domain in terms of individuals (specific entities), concepts or classes (sets of individuals with shared characteristics), and…

Description Variation(also: AD Variation, Alternative Description)

Multiple versions of audio descriptions for the same video content, each reflecting different stylistic choices, levels of detail, or narrative focuses. Description variations recognize that BLV users have diverse preferences and that a single description cannot serve all needs…

Descriptive Labels(also: Descriptive Naming, Semantic Labels)

Text labels for visual options (such as fonts, colors, and filters) that describe their perceptual or aesthetic qualities rather than simply providing a technical name. For example, labeling a font as "Comic Sans: casual and playful" or a color as "orange: warm and energetic"…

Descriptive Video Service(also: DVS, Described Video)

A service that provides audio descriptions of visual content in television programs, films, and other video media for blind and low-vision viewers. Originally developed by WGBH in Boston in the 1980s, DVS was one of the earliest systematic efforts to make visual media accessible…

Desensitization(also: Haptic Adaptation, Vibrotactile Adaptation)

Desensitization in the context of haptic feedback refers to the gradual reduction in a person's sensitivity to continuous or repeated vibrotactile stimulation on the skin. When haptic actuators vibrate continuously at the same location, users progressively become less able to…

Desexualization(also: Asexualization)

The social phenomenon in which disabled people are assumed to be uninterested in, incapable of, or undeserving of sexual relationships and intimacy. This manifests as invasive questioning about sexual function, disbelief when disabled people form romantic relationships, and the…

Design Constraints(also: Creative Constraints)

Limitations or boundaries placed on the design process, whether intentional (such as toolkit components in a prototyping workshop) or inherent (such as budget, technology, or time constraints). In design research, constraints can paradoxically foster creativity by focusing…

Design Exclusion(also: Exclusion Audit, Technology Exclusion)

The process by which certain users are prevented from effectively using a product or service due to mismatches between the design of the technology and their abilities, circumstances, or available resources. Design exclusion can result from physical, sensory, or cognitive…

Design Fiction(also: Speculative Fiction, Diegetic Prototype)

A design research practice that creates fictional but plausible artifacts, scenarios, or narratives set in imagined futures to provoke discussion, surface assumptions, and explore the social and ethical implications of emerging technologies. Unlike traditional prototyping,…

Design Fixation(also: Fixation Effect)

A cognitive phenomenon in the design process where exposure to existing examples or initial solutions constrains creative thinking, causing designers to replicate or only minimally modify those examples rather than exploring original alternatives. In AI-assisted design, fixation…

Design Informant(also: Informant Design)

A participatory design role in which users contribute to the design process by providing input, preferences, and feedback, but the researcher retains responsibility for interpreting this data and making design decisions. This approach contrasts with the Design Partner model…

Design Justice

A framework that centers the perspectives of people who are most impacted by design decisions, ensuring that design processes, practices, and outcomes distribute benefits and burdens equitably. Coined by Sasha Costanza-Chock, design justice challenges traditional design power…

Design Pattern(also: Interaction Pattern, Pattern of Assistive Interaction)

A reusable, generalised description of a solution to a commonly recurring design problem, expressed in a way that can be applied across different contexts without prescribing a specific implementation. In assistive technology design, interaction patterns describe the functional…

Design Probe(also: Technology Probe, Design Provocation)

A research method in which a functional or semi-functional prototype is deployed with participants not primarily to test usability, but to provoke discussion, elicit design insights, and explore future possibilities. Design probes are deliberately open-ended, encouraging…