Glossary
Terms used in accessibility research and practice. Each entry has a definition, common aliases, and category tags.
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- Perkins Brailler(also: Brailler, Braille Writer)
- A mechanical device for writing braille, manufactured by the Perkins School for the Blind since 1951. The Perkins Brailler has six keys corresponding to the six dots of a braille cell, a space bar, a backspace key, and a line advance key, allowing users to emboss braille…
- Photosensitivity(also: Light Sensitivity, Photophobia)
- An abnormal sensitivity to light that can cause discomfort, pain, or visual disturbance. Photosensitivity affects many people with visual impairments and certain neurological conditions including migraine and epilepsy. In digital accessibility, photosensitivity considerations…
- Pitch Mapping(also: Pitch-Y Mapping, Frequency Mapping)
- A sonification technique that maps data values to auditory pitch, where higher values produce higher-pitched sounds and lower values produce lower-pitched sounds. In accessibility contexts, pitch mapping is commonly used to represent the vertical position (Y-axis) of data points…
- Presbyopia(also: Age-Related Farsightedness)
- An age-related vision condition where the eye gradually loses its ability to focus on nearby objects, typically becoming noticeable in the early to mid-40s. Presbyopia affects virtually everyone as they age and significantly impacts web accessibility, making small text difficult…
- Presentation video(also: Lecture recording, Recorded lecture)
- A video recording of an instructor delivering content alongside visual materials such as slides, whiteboards, or demonstrations. Presentation videos present unique accessibility challenges because they combine spoken content with visual actions like pointing, annotating, and…
- Proactive description(also: Proactive notification, Unsolicited description)
- The ability of an assistive system to automatically provide relevant visual or environmental information without requiring the user to explicitly request it. For blind and visually impaired users navigating real-world environments, proactive description is critical — a human…
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