Synesthesia

Synesthesia is a perceptual trait in which a stimulus or thought in one domain automatically and consistently evokes an additional experience, such as seeing colors when hearing sounds or reading letters.

Grapheme–color synesthesia: A form of synesthesia in which letters or numerals evoke particular colors. It is a well-studied example of a symbol reliably triggering a color experience.
Perception: The processes by which sensory information is organized and interpreted. Synesthesia involves additional experiences within perception.
Ordinal linguistic personification: A form of synesthesia in which ordered sequences, such as numbers or days, evoke personalities or social relationships. It shows that synesthetic concurrents can be person-like rather than sensory qualities.
Francis Galton: An English polymath whose nineteenth-century research described number forms and other unusual mental experiences. His early reports brought synesthetic experiences into scientific discussion.
Synaesthesia in literature: A literary device that describes one kind of sensory experience in terms of another. Literary sensory blending uses language that can resemble, but does not prove, a perceptual trait.
Chromesthesia: A form of synesthesia in which sounds evoke colors or visual shapes. It exemplifies the blending of auditory and visual experience.
Mental imagery: The experience of representing sensory information in the mind without its immediate presence. Synesthetic concurrents are typically described as automatic, unlike intentionally formed imagery.
Mirror-touch synesthesia: A form of synesthesia in which observing another person being touched evokes a tactile sensation on one's own body. It links observed touch to a felt bodily experience.
Cytowic: An American neurologist known for clinical research and writing on synesthesia. His work helped renew scientific and public interest in the phenomenon.
Synesthesia in art: Artistic practices that connect sensory domains, including sound with color or visual form. Artists have used cross-sensory correspondences to represent or evoke synesthetic experience.

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