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Thanks everyone for your thoughts on Monday night!  I find that I am intrigued by the underlying mechanism explaining how savants such as Steven Wiltshire and Daniel Tammet could possibly store such vast amounts of information in their brains.  Stories of these peoples’ extraordinary memory are almost unfathomable to us.  However, scientific research has not yet found a limit to the amount of information that the brain can store, so why should we be so amazed?  We have talked several times about the possibility that gaining an ability due to a disability may be because an inhibition mechanism in the brain is turned off by the disability.  Our brains purposefully do not remember 99.9% of sensory input because it is unnecessary.  We only remember something if we commit to processing and encoding the information to move it from short-term memory to long-term memory.  Perhaps our brains could remember all of the input, but there is an inhibitory mechanism that prevents memory formation without an extra encoding process.  It could be this inhibitory mechanism that is disabled in people like Steven Wiltshire. 

            I am also interested in the question of why eidetic images are evolutionarily advantageous.  If Paul is right and the brain cannot store eidetic images for long periods of time, then they seem pretty useless.  How would it help our ancestors to be able to visualize exact details of a scene two minutes afterwards?  On the other hand, if they could recall an eidetic image months later I could see how this might be helpful.  For example, it could possibly help our nomadic ancestors in identifying specific locations.  Still, I’m finding it difficult to rationalize the evolutionary significance of eidetic memory.