Grapheme-color synesthesia

Grapheme-color synesthesia is a neurological phenomenon where individuals automatically associate specific colors with certain written symbols, such as letters or numbers. For example, a person might see the letter "A" as red and "5" as blue, regardless of the actual color of the ink. These color associations are consistent over time and are involuntary—meaning they happen automatically and cannot be turned off. This condition occurs because the brain's sensory processing areas for visual symbols and colors are interconnected, causing these cross-sensory experiences without any external stimuli actually producing the colors.