Mulling over the signs of sensory dysfunction(?) in Charlie this year, the hands over the ears (more of htis a few months ago) and all the recent squinting (right eye especially), I’ve been thinking about synesthesia, which is (according to this MIT site):
involuntary joining in which the real information of one sense is accompanied by a perception in another sense.
Someone with synesthesia might see certain letters or numbers as having certain colors or textures, as Daniel Tammet writes in his book Born on a Blue Day: A Memoir of an Extraordinary Mind. Researchers at CalTech have recently discovered auditory synesthesia as the Quantum Pontiff notes. Per Nature News, for someone with auditory synesthesia, “flashes and moving images trigger the perception of sounds.” Charlie has long, long been drawn to colors, shapes, and textures over much else and I’ve wondered if he is getting extra sensory input, and even too much input, from the things in the world around us?