Sandman, read the "The Mind of A Mnemonist" by A. R. Luria. He explores the phenomena extensively.
"The Man who Mistook his Wife for a Hat" by Oliver Sacks shares many clinical tales, all fascinating, although he doesn't explore your interest extensively.
My favorite clinical tale (Oliver Sacks) was one from the aphasia ward. Global aphasics are incapable of understanding spoken languages. If you could somehow remove all body language (facial expressions & etc), then a global aphasic would be unable to understand you.
However, global aphasics are usually very intelligent and understand everything (and more) that is said to them. They read body language. You can have entire conversations with them and never know they suffer from aphasia.
Anyway, Dr. Sacks was walking past the aphasia ward and was stunned to hear roars of laughter. They were listening to a Ron Reagan speech and they were reacting to the false tones and cadences of his voice.
curly