Experience: I feel other people's pain. When I watch a film, I feel as if I'm in starring in it.
The Girl With The Dragon Tattoo was horrific. My friend invited me to see it, and I had no idea what it was about – I normally try to avoid dramas and thrillers. When the character Salander was tortured, I felt as if my body was being beaten; I could physically feel the sensation of being attacked. Colour my world. Colour does not exist.
Not out in the world at any rate. All that exists in the world is a smooth continuum of light of different wavelengths. Colour is a construction of our brains. A lot is known about how the brain does this, beginning with complicated circuits in the retina itself. Synesthesia overview. Synesthesia. How someone with synesthesia might perceive (not "see") certain letters and numbers.
Synesthetes see characters just as others do (in whichever color actually displayed), yet simultaneously perceive colors as associated to each one. Synesthesia (also spelled synæsthesia or synaesthesia, from the ancient Greek σύν [syn], "together", and αἴσθησις [aisthēsis], "sensation") is a neurological phenomenon in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway. People who report such experiences are known as synesthetes.