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Bobby brought up the point last night that, because Wiltshire's is autistic, the amount we can learn about normal visual memory through his ability is limited.  This seems true; it may be misleading to draw conclusions about normal memory by observing the functions of a brain that is fundamentally different. However, I can think of two possible reasons to believe that we could still learn about normal brain function through case studies such as Wiltshire's. For one, while I don't pretend to know much about autism, I have heard several theories suggesting that those with autism share similar neural circuitry with "normal" people, but represent the extremes of certain spectrums. For example, I remember learning about a particularly contentious theory that the autistic brain is only a more extremely masculinized brain (less emotional, more rational [you can see why this was contentious], etc.). If this is true -- if autism does in fact only signify an extreme form of normal circuitry -- then perhaps we can learn about normal brain functioning through Wilkshire. His spectacular ability could be understood as only a more extreme version of what all people have, given that his functions inhere in similar but extreme circuitry.

A second reason that we may be able to generalize instances of photographic/eidetic memory to normal functioning relates to another point brought up last night. We each have some degree of eidetic memory; as pointed out, we know where a quotation we're looking for resides on the page. Moreover, as far as I understand, the current model of normal memory processes involves a short period of sensory memory, prior even to short term memory. If accessed quickly enough, we can scan this transient sensory image in a similar way to those with eidetic memory. This suggests that instances of photographic memory (or at least eidetic memory) may only serve as extreme forms of mechanisms we all have access to. Should eidetic memory only be an extreme case of normal memory, we may expect to learn about normal memory through instances of this phenomenon.