As you may have noticed, I’m reading my way through a number books by neurosurgeons and brain scientists, as part of reviewing state of the art understanding of “perception”. Recently I read Edeleman, Zeman and Austin’s books, and more recently started Oliver Sacks “The Man Who Mistook His Wife For A Hat”, full of intriguing stories (in the first half) about case studies where his patients have misperceived the world.
As well as the eponymous man who really did try to put his wife on his head (!) as he stood up to leave Sacks’ office, the cases range from total amnesia, short and long term amnesia before, within and after time bounded periods, selective amnesia, and other modal mis-perceptions – phantom limbs (perceived limbs that have actually been lost) foreign parts (actual body parts perceived as alien, and practically useless, or worse), ability to perceive only part of a field of view, perceiving moving objects but not stationary, to name but a few.
Prognoses and outcomes vary, but one is constantly amazed at the dynamism and plasticity of the central nervous system to re-learn alternative means of perceiving and dealing with the world, once the individual brain is shown the reality of its situation. Very like Adam Zeman’s case of the patient who learned to “see” through a patch of skin on their abdomen – weirder things have happened. Read Sacks.
Most striking, given the previous post, are the various blindnesses to words or meaning – quite independently, often as part of other degenerative diseases of the elderly who, incidentally, provide Sacks with a wealth of case-studies. In “The President’s Speech”, referring to a thinly disguised Ronald Reagan (?), he refers to a group of individuals who gained every nuance of honesty, intent and spin from his voice-tones, facial expression and body language, much to their amusement, despite not perceiving a single word he actually said, contrasted with a very elderly Emily D (poetess – thinly disguised also ?) who could not understand the sense of sentences people spoke to her, unless they were grammatically correct, and pronounced very clearly. She had no means of detecting irony, truth, humour, tones or moods of any kind, beyond the semantics of the words used.
In all Sacks cases, the problems are with “processing” the data, not with primary sensory or motor defects. What these “freaks” tell us – and they are rare cases – is a great deal about how our mind really works to perceive the apparent world, and build a coherent model of it. Also, being at that fuzzy brain / mind boundary of “thinking meat”, the issues cannot fail to have an epistemological or other philosophical angle.