Feb 25 2008

Would You Want A Perfect Memory?

Brad Williams has a phenomenal memory. Give him a date, even decades ago, and he will give you numerous accurate details about the events of that day. He is not the first person to crop up with such verifiable preternatural memory. The existence of such persons generates many questions. What is it, exactly, that is different about their brains that gives them such astounding memory? Is this enhanced memory due to superior memory function itself, or some other aspect of information processing? Do most people have the capacity for such memory that is being inhibited somehow, or do their brains contain new anatomical or neurophysiological features that most people lack? Why doesn’t everyone have similar memory? Is having such a memory a boon, a bane, or a little of both?

I wish I had the answers to these questions. Dr. James McGaugh, who is studying Brad Williams, is quoted as saying:

You want the Nobel Prize right now? Tell me that answer and I’ll publish it. We don’t know. We do know that he carries this information with him, that it’s detailed, that it’s just there. That’s what we want to know — why is it there?

I am sure we will learn some very interesting things about Mr. Williams and those like him, but right now we do not have the technology to image brain function with sufficient resolution to probe where the answer likely lies. Brain function is dependent upon the pattern of neuronal connection and the details of their synapses, receptors, and neurotransmitters. But what can we infer from what is currently known?

Brad Williams reports that his memory is especially good for dates, he seems to remember easily when things happened. This implies that perhaps his mnemonic skill is not something generic with memory but perhaps has to do with the processing of information related to events and dates. Perhaps this is similar to those chess masters who can remember every move of a complex game – stemming more from their talent and knowledge of chess than raw memory power. There is also the Japanese man who recited pi from memory to 83,431 digits – clearly a superior memory but with a special affinity for numbers.

At first blush is makes more sense (or at least it is more aesthetic) to hypothesize that this super memory is a new ability in these individuals, rather than a talent most humans possess but is inhibited. Why would our brains contain such a ability only to inhibit it in all but a few? But there is some reason to give this notion some attention. In 2004 Young et. al. published their study which showed that by interrupting the function of the frontotemporal lobes with magnetic stimulation they were able to reproduce savant-like memory ability in some ordinary subjects.

The implications of this are extremely interesting. If this finding holds up to future research it means that our brain to contain hidden ability. There is also evidence that animals, particularly our closest cousins, may have superior skills at certain memory or processing tasks. Why would this be? There are several possibilities.

First, we should not assume that the only measure of memory is its fidelity. We must consider what the purpose of memory is from an evolutionary point of view. Our memory provides for us useful information to help us survive – to avoid mistakes we or others have made in the past, remember our friends and enemies, etc. The evolutionary purpose of memory is to guide our future behavior. For this purpose perhaps it is best that the emotion, theme, and implications of a past event is well remembered, but the details are often not important. In fact, human memory significantly favors emotional stories over details.

If many of the details that get crammed into our brains are not useful that would still not necessarily favor their forgetting, unless they were a detriment. Another subject being studied by McGaugh, a woman known only by her initials AJ, recounts:

Most have called it a gift, but I call it a burden. I run my entire life through my head every day and it drives me crazy!!!

So perhaps loads of useless details are more of a distraction than a help. This accords well with our general model of how the human brain processes information. We miss most of what happens, focusing our attention only on certain bits we deem relevant or important. We filter the rest out as a distraction. The inability to filter sensory input is a terrible dysfunction – so perhaps it is the same with memory.

Another possibility (not mutually exclusive) is that as our brains evolved in the last few million years we added higher level processing of information in our greatly expanded frontal lobes. This increased complexity of processing slowed down the whole process and made some of the components of information processing (like numbers or dates) less efficient and the memory of such things less accurate. The advantages of being deeper thinkers may have come at the expense of the quickness and fidelity of certain types of memory.

The existence of these rare individuals with incredible memory for certain details will likely be useful to teach us about human memory and brain function in general. But they also remind us of the strength and weakness of ordinary human memory. Our memories are not primarily for remembering details. In fact almost everything we remember about our past is likely to be highly inaccurate in detail. Our memories are primarily for telling ourselves stories about our past. Human memory is a flawed and subjective narrative filled with moral and practical lessons – it is not a recording of what actually happened.

This knowledge of human memory is something no skeptic should forget.

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