Glossary

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Active Perception(also: Active Sensing, Sensorimotor Exploration)

A view of perception in which the perceiver is not a passive receiver of stimuli but an active agent who moves, orients, and manipulates the environment to gather the sensory information needed for a task. In accessibility and sensory substitution research, active perception is…

Aphantasia(also: Mind Blindness)

Aphantasia is a neurological condition in which a person is unable to voluntarily create mental images or visualize objects, people, or scenes in their mind. It affects an estimated 2-5% of the population and exists on a spectrum from reduced imagery to complete absence. In…

Attention Tunneling(also: Visual Tunneling, Attentional Tunneling, Cognitive Tunneling)

A phenomenon in which a user concentrates so narrowly on a primary information source - typically a visual overlay, head-up display, or instrument - that they fail to notice relevant events, objects, or hazards in their surrounding environment. In augmented and mixed reality,…

Awe(also: Awe Experience)

Awe is an emotional response to perceived vastness — physical, conceptual, social, or spiritual — that requires a person to update their mental models to accommodate it. It blends wonder, reverence, and sometimes fear, and is associated with reduced self-focus, increased…

Body Awareness(also: Body Schema, Body Image)

The understanding of one's own body including its structure, posture, position in space, and relationship to the environment. Body awareness encompasses both the physical sense of where body parts are (proprioception) and the cognitive understanding of body shape, proportions,…

Body Ownership Illusion(also: BOI)

A perceptual phenomenon in virtual reality where users perceive a virtual body or avatar as their own, experiencing it as an extension of their physical self. This illusion is fostered when the virtual representation performs the same actions as the user's actual body, such as…

Causal Listening

A mode of listening, identified by composer and theorist Pierre Schaeffer, in which the listener focuses on identifying the source or cause of a sound — for example, hearing crumpling paper and recognising it as something being discarded, or hearing a camera shutter and…

Central Vision(also: Foveal Vision)

Central vision is the area of sharpest sight in the visual field, corresponding to the fovea at the centre of the retina. It is responsible for detailed tasks such as reading, recognizing faces, and distinguishing fine detail and colour. Loss of central vision, commonly caused…

Change Blindness(also: Changeblindness, Inattentional Blindness)

Change blindness is a perceptual phenomenon in which observers fail to notice changes to a visual scene when the change coincides with a visual disruption such as an eye movement, blink, or brief occlusion. In accessibility contexts, change blindness is particularly relevant for…

Color Perception(also: Color Vision, Chromatic Vision)

Color perception is the ability to detect, distinguish, and identify colors. Impairments in color perception range from complete color blindness (achromatopsia) to partial deficiencies in distinguishing specific color ranges, such as red-green or blue-yellow color vision…

Cross-Modal Perception(also: Multisensory perception, Cross-modal integration)

The neural and perceptual integration of information arriving through two or more sensory channels — such as vision, hearing, touch, and proprioception — into a coherent experience of the world. Cross-modal perception explains phenomena such as the McGurk effect,…

Cross-Sensory Translation(also: Sensory Substitution, Sensory Translation, Cross-Modal Translation)

The process of converting information from one sensory modality to another — for example, representing visual information through touch, sound, smell, or taste. In exhibition accessibility, cross-sensory translation is used to make visual artworks accessible to blind and low…

Cross-modal(also: Cross-modal Correspondence, Cross-modal Perception)

The phenomenon whereby information or stimulation in one sensory modality (such as vision) systematically influences or corresponds with perception in another modality (such as hearing or touch). In accessibility contexts, cross-modal correspondences are exploited in sensory…

Cross-modal Congruency

The temporal, spatial, and semantic alignment of sensory cues during an interaction — for example, a visual event and its accompanying sound occurring at the same moment and in the same location, with matching emotional tone. Congruency differs from correspondence:…

Cross-modal Plasticity(also: Cross-modal Reorganisation, Cross-modal Cortical Recruitment, Sensory Substitution)

A neurological phenomenon in which brain regions typically dedicated to processing one sensory modality are repurposed to process information from another sense, often as a result of sensory deprivation. In deaf individuals, auditory cortical areas can reorganise to support…

Cutaneous Perception(also: Cutaneous Sense, Cutaneous Feedback, Tactile Perception)

The sensory experience derived from receptors beneath the surface of the skin that respond to temperature, pain, and pressure. In the context of assistive technology, cutaneous perception enables users to detect surface textures, raised patterns, and embossed details through…

Cybersickness(also: VR Sickness, Simulator Sickness, Virtual Reality Motion Sickness)

A form of motion sickness experienced during virtual reality use, characterized by symptoms including nausea, disorientation, dizziness, eye strain, and general discomfort. Cybersickness occurs due to sensory conflicts between what the visual system perceives (movement in the…

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…

Discrimination Ellipse(also: Discrimination Ellipsoid, MacAdam Ellipse)

A region in a color space surrounding a given color within which other colors cannot be distinguished from it by an observer. In two dimensions this region forms an ellipse; in three-dimensional color spaces it becomes an ellipsoid. The size and shape of discrimination ellipses…

Embodiment(also: Virtual Embodiment)

The sense of inhabiting and controlling a virtual body in VR, feeling that the avatar is an extension of oneself rather than a separate entity. Embodiment is fostered through synchronized tracking of physical movements to avatar movements, visual congruence between the user's…

Emotional Mediation Hypothesis

A theoretical account, originating in work by Palmer and colleagues, that explains cross-modal associations between sensory attributes (such as colors and musical timbres) as being mediated by shared emotional meaning rather than by direct perceptual mapping. For example, people…

Environmental Awareness(also: Situational Awareness, Environmental Sound Awareness)

The perception and understanding of what is happening in one's physical surroundings, particularly through auditory cues. For Deaf and hard of hearing individuals, environmental awareness is often reduced because many everyday signals — appliance timers, doorbells, approaching…

Environmental Flow(also: Optic Flow, Sensory Flow)

The ordered changes in a pedestrian's distances and directions to surrounding objects that occur while walking, providing continuous feedback about spatial position and movement through the environment. For sighted people, environmental flow is primarily visual (optic flow), but…

Exploratory Procedures(also: EPs)

Exploratory procedures are stereotyped movement patterns that people use when examining objects through touch to identify specific properties. Defined by Lederman and Klatzky in tactile perception research, these are hand and finger configurations that do not correspond to…

Fixation(also: Visual Fixation, Gaze Fixation)

A period during which the eyes remain relatively stationary on a specific point or area, typically lasting 100 to 600 milliseconds. During fixations, the brain processes the visual information at the point of gaze. In eye-tracking research, fixations are a primary unit of…

Frequency Selectivity(also: Auditory Frequency Resolution, Critical Band Selectivity)

Frequency selectivity is the auditory system's ability to separate closely-spaced frequencies into distinct perceptual streams — the reason a typical listener can follow one voice in a crowd, hear the bass line under a melody, or distinguish similar speech sounds like 's' and…

Gestalt Grouping Principles(also: Gestalt Principles, Gestalt Laws of Perceptual Organization)

A set of principles from perceptual psychology that describe how the human visual system organizes individual elements into coherent groups and patterns. Key principles include spatial proximity (elements near each other are perceived as related), connectedness (elements joined…

Graphical perception(also: Chart perception, Visual data perception)

The cognitive process by which people extract quantitative information from visual data representations such as charts, graphs, and maps. Graphical perception involves comparing positions, lengths, areas, angles, and colours to make judgements about data values and…

Haptic Exploration(also: Tactile Exploration, Touch Exploration)

The process of acquiring spatial and object information through systematic touch and hand movements. Haptic exploration involves active manipulation and movement across surfaces to perceive shape, size, texture, temperature, and spatial relationships. For people who are blind or…

Haptic Field of View(also: Tactile Field of View, Haptic Aperture)

The limited area that can be perceived through touch at any given moment, analogous to the visual field of view but much more restricted. While vision allows perception of an entire scene simultaneously, touch typically provides information only from the area directly under the…

Haptic Perception(also: Tactile Perception, Touch Perception)

The ability to perceive and interpret information through the sense of touch, including the detection of texture, shape, temperature, pressure, and vibration. Haptic perception is a primary information channel for blind and low vision people and is central to the use of…

Head-related transfer function(also: HRTF)

A response function that describes how sound from a specific point in space is filtered by the shape of the outer ear, head, and torso before reaching the eardrum. HRTFs are unique to each individual and are used in spatial audio rendering to create realistic 3D sound over…

Immersion

The objective level of sensory fidelity that a VR system provides, including visual quality, spatial audio, and haptic feedback that work together to create a convincing virtual environment. Unlike presence (which is subjective), immersion refers to the technical capability of…

Inattentional Blindness(also: Perceptual Blindness)

Inattentional blindness is the failure to notice a fully visible but unexpected object or feature when attention is directed elsewhere. It is distinct from change blindness (failure to notice a change between two views): inattentional blindness is about missing something that…

Just-Noticeable Difference(also: JND, Difference Threshold, Differential Threshold)

The smallest detectable difference between two stimuli that a person can perceive. In accessibility contexts, JND is commonly applied to color, contrast, and audio levels—determining the minimum change needed for users to distinguish between two values. For color vision, JND…

Kinaesthetic Perception(also: Kinesthetic Perception, Kinaesthesia, Kinesthesia)

The sensory awareness of the position, movement, and force of body parts, derived from receptors in muscles, tendons, and joints. In the context of haptic technology and accessibility, kinaesthetic perception provides information about the shape, weight, and spatial extent of…

Kinesthetic(also: Kinaesthetic)

Kinesthetic refers to the sense of body movement, limb position and muscular effort, arising from receptors in muscles, tendons and joints and closely related to proprioception. In accessibility and interaction-design contexts, kinesthetic cues - such as the pull a partner…

Kinesthetic Awareness(also: Kinesthesia, Movement Awareness)

The conscious perception of body position, movement, and muscle tension derived from internal sensory receptors in muscles, tendons, and joints. For sighted people, kinesthetic awareness is reinforced by visual feedback — watching their own movements and observing others. People…

Kinesthetic Perception(also: Kinesthesia, Proprioceptive Perception)

The sensory ability to perceive the position, movement, and forces acting on one's body and limbs through receptors in muscles, tendons, and joints. Kinesthetic perception encompasses awareness of limb position (proprioception), detection of movement and velocity, and sensing of…

Kinesthetic Perception(also: Kinesthesia, Kinesthetic Sense, Kinesthetic Feedback)

The sensory awareness of body position, movement, and force through receptors located in muscles, tendons, and joints. In assistive technology, kinesthetic feedback is a component of haptic interaction where users perceive the position of their limbs and the forces applied to…

Material Perception(also: Material recognition)

The perceptual processes by which people identify and characterize the materials that objects are made of — such as wood, metal, glass, leather, fabric, or stone — using visual, tactile, auditory, and sometimes thermal cues. Material perception goes beyond recognizing object…

Mirror Neuron System(also: Mirror Neurons)

The mirror neuron system is a network of brain regions that activate both when a person performs an action and when they observe another person performing the same action. It is implicated in motor simulation, action understanding, and learning by imitation. Neuroscientific…

Monotropism

A cognitive theory of autism, developed by Dinah Murray, Mike Lesser, and Wenn Lawson, that describes autistic attention as tending to be pulled strongly into a narrow focus (one "attention tunnel") rather than distributed broadly across many concurrent inputs. Monotropism…

Multisensory(also: Multisensory Design, Multisensory Interaction)

An approach to design and interaction that engages multiple human senses — such as sight, hearing, touch, smell, and taste — to convey information and create richer experiences. In accessibility, multisensory design is valuable because it provides alternative channels for…

Multisensory Integration

The neural and perceptual process by which the brain combines information from different sensory modalities — sight, hearing, touch, proprioception — into a unified percept. Integration relies on temporal and spatial binding windows that widen with age: older adults tolerate…

Optic Flow(also: Visual Flow, Optical Flow)

The pattern of apparent motion of objects, surfaces, and edges in a visual scene caused by relative movement between the observer and the scene. Optic flow provides critical information about self-motion, speed, direction, and the structure of the environment. It plays a key…

Parallax(also: Visual Parallax, Binocular Parallax)

Parallax is the apparent displacement or difference in position of an object when viewed from two different vantage points. In human vision, binocular parallax — the slight difference between the images seen by each eye due to their spatial separation — is a primary cue for…

Perceptual Bandwidth(also: Sensory Bandwidth, Information Bandwidth)

Perceptual bandwidth refers to the rate at which a sensory channel can transmit information to the brain. In accessibility contexts, the concept highlights the fundamental asymmetry between vision and hearing: vision has extremely high bandwidth, allowing a sighted person to…

Perceptual Cycle(also: Perceptual Response Time, Perceptual Processing)

In the Model Human Processor framework, the perceptual cycle is the time required for a person to perceive and register a stimulus from their environment, such as seeing a visual change on screen. The perceptual cycle time for both able-bodied and motor-impaired users is…

Perceptual Integration(also: Perceptual Binding)

The process by which the brain combines information arriving through different sensory channels — vision, hearing, touch, proprioception — into a single coherent percept of an object or event. Perceptual integration depends on temporal synchrony (cues arriving within roughly 100…