Build me a memory

kw: book reviews, nonfiction, memory, memory studies, psychology

We describe memories by relating them to the familiar, and these days, that means a computer is involved. But the way a computer functions is about as different from brain work as it can be. The most enduring metaphor for memory is the storehouse. We imagine opening drawers and cupboards to find a memory, and pulling it out whole, to be viewed or even re-experienced. With more thought, we might consider that some part of our brain has many cubbyholes where memories go. People with "good memories" then have a better index than the rest of us, or are quicker sorting through all the cubbies.

Think instead of a warehouse full of spare parts: boxes of different kinds of sunsets, bins with collections of similar sounds or smells of people and places we've experienced, piles of "the feel of walking in narrow lanes" or holding hands in various ways, and albums of the look and feel of loved ones and friends and acquaintances. At one end of the warehouse, a catalog index directs us to the various bits, so we can relive or review that walk, hand in hand with a lover, speaking together, turning down an alley to stop at the verge of a hill and seeing just that sunset together. Many memories start with a smell, and you are suddenly in that bakery with, say, your long-deceased grandmother on shopping day. I imagine the warehouse might resemble the workshops in Mythbusters.

Charles Fernyhough set out to write a book about the science of memory, and has delivered a book of stories, with the science to explain them: Pieces of Light: How the New Science of Memory Illuminates the Stories We Tell About Our Pasts. I confess I didn't fathom the interplay of the Medial this and the Posterior that. I have a vague idea of the Amygdala and Hippocampus, but as a diagram in the book shows, some dozen named parts of the brain are involved in "Autobiographical Memory". I suppose I ought to have studied a bit as I read along, but I was so taken with the stories (Charles, that is a compliment) that I did not.

But I think the view from 10,000 feet is enough for now. The "Pieces of Light" of the title aptly summarize the way a memory surfaces: bits of various kinds are brought together at some switching center—which is probably the Hippocampus—and reviewed. Such a process affords us much more space for storing memories than if each memory were a five-sense videotape record. Thus, those parts of an experience that we pay attention to, or that thrust themselves into our attention, are picked apart and stored in some sorted manner, and indexed for retrieval. Repeated experiences of the same place or kind of event are in part blended together, and in part kept separate when there are singular experiences on certain occasions.

Quick: try to remember every one of your own birthday parties. If you have a family like mine, there were at least 15 or so that occurred while you were in your parents' home, and a few others since you began to live on your own. Though I have been the "target" of at least thirty birthday parties, the only one I remember is when my beard caught on fire as I was blowing out the candles (so I was 23 that year); my dad clapped both my cheeks with his hands to put it out, growled, "I have been waiting a long time to do something like that", and gave me a grin. Otherwise, the parties are a mishmash of the kids I knew and a vague feeling of too much cake and ice cream and soda. I don't recall any of the gifts!

Another notion: try to remember the second time you did something, such as driving by yourself or making love or hang-gliding. Aren't a lot of our memories all about the novelties? This makes sense from a biological and evolutionary perspective, as the author explains. When we are tiny, everything is new, and we struggle to make sense of it all. We are automated categorization machines, and work at increasing efficiency as we gather memories with which to compare new events.

While studies of people with various kinds of brain damage or under the spell of certain drugs may indicate the function of various parts of the brain, we find that the workings of the intact brains that most of us have are not really geared toward faithfully recording our life. We don't really have a camera crew tucked inside, laying down tracks of videotape (or SD card MPEG files). Later experiences influence the way we remember those "first times". And, because we store the imaginings we have about others' stories in the same way we store our own, the record may be quite faithful for certain details, but rather sloppy about others.

Fernyhough's focus is autobiographical memory, the memories that tell our own story. They are different, in quality if not in kind, from memories such as the times table or the way we make apple fritters. We could say that our memory is not so much a textbook of "My History" as it is a historical novel: many genuine events (or portions of them) strung together with fabrications and borrowings to make a coherent whole. Coherence matters to us more than exactitude. And we tend to remember what happened a lot better than when it happened. In my story of the beard fire, I had to think to recall my age, and had I worn a beard for more than just that year, it may not have been possible.

It makes sense that our memory serves us according to the needs our ancestors had. It is usually less important to recall the exact year of, say, each time the family camp was flooded, and more important to remember what was done to rescue this or that person or to restore the damage. I think of it as akin to managing by exception: we remember the first flood, and recall the others by how they differed from it.

Shocking events that lead to "flashbulb" memories illustrate the extreme edge of memory use. Something in our brain realizes, "This is so unusual it must be VERY IMPORTANT. Record it faithfully!" At least the first time. Thus, people my age have clear memories of the assassination of JFK—where we were and who we were with and how we heard it—but are less clear when recalling the assassination of Bobby Kennedy or Martin Luther King. The events were just as shocking but were no longer novel. Similarly, the Challenger explosion produced sharper memories for us than the incineration of Columbia.

The "first time effect" is critical, and goes a long way to explain the juvenile bump in our collection of important stories. The way our brains develop allows only a few very early memories, so the "formative years" are from about age 10 to 20 or so. In a late chapter we read of the author's grandmother, recalling many events in the 1920s and 1930s, when she was a girl, and the world was in crisis, particularly for a Lithuanian family in the midst of emigration and assimilation into a new culture. He tries bringing a Yiddish-speaking acquaintance to meet her, thinking she may remember some things better if asked in the language of her childhood. A few new memories do surface, but she'd been fluent in English from such an early age that she no longer understands Yiddish very well. A visit from a woman she'd been in school with is another story (or a lot of stories!). They hadn't met in 80 years (one was 93 the other 94), so once they got the small talk out of the way, they had a lot to talk about as they shared those childhood and pre-teen memories.

So here is a clue, if you have been gathering stories from an aged relative. At some point, round up a childhood friend or favorite cousin, and get them reminiscing. I had some hopes of doing this for my father a few years ago, when I visited his childhood home town. He had given me a list of people whom he thought might still live there, and I hoped to find one and call Dad for them to have a chat. At the end of the trip, I reported to him that I'd found them all…in the cemetery. By age 88 he had outlived his entire home town. Now he is 91½, and still pretty sharp, at least for old stuff. I'll be with him for the next few days (I have to cross a continent to see him), and I'll see what I can gather.

Meantime, we all need to realize that it is hard to keep most memories "pure". Later experiences of an event or place, or with similar import, can influence the way we recall just this experience in that place. This is important. State justice departments are only now changing how they make proper use of "eyewitness" testimony. The Biblical requirement that two witnesses had to agree was very wise.

We are like the 7 blind men encountering an elephant. To one it seems like a wall, to another it is like a snake. We each remember different stuff about a shared experience. Nobody gets it all right. We even edit our stories about ourselves, and when we forget the editing, whose story are we telling? Ah, that's the fun part, for we are who we remember we are.

The middle memory

kw: musings, memory, thinking

I love it when a book gets me thinking. I reviewed How to Think Like a Neandertal, by Thomas Wynn and Frederick L. Coolidge, yesterday. A portion of their discussion of Neandertal cognition was memory.

Usually, memory is considered to have two varieties, long term and short term. Short term memory can hold a phone number, or someone's name, or a short list of items, for a few seconds, up to a minute or so. Repetition of a short-term memory, or a sudden shock, can fix it in long term memory, which lasts decades. But another term came up in the discussion of tool making and expertise: working memory. It wasn't really quantified.

Is working memory some combination of short- and long term memory, or something distinct? It seems to work this way. When you are engaged in a task, particularly one which is not wholly familiar, you may have to hold several things in memory for periods of minutes to hours. Yet, once you are done, all the memories fade.

I took advantage of this whenever I wrote a computer program or subroutine. In the very early days, I did what beginning programmers usually do, and built stand-alone applications (today folks just call them apps). They consisted of a stack of FORTRAN code that just did what I wanted it to do, usually. Whether extract certain numbers from a list or calculate a Fourier series, I just set it all up to do what I wanted. While I was writing, particularly in the days of the card punch (no terminal screen to help), I kept the entire program in mind as I spun out the code, line by line.

As time went on, I learned to break up a process into chunks, and write the chunks one at a time. I began to rely on callable routines. Eventually, I could write a program with a general outline:

Program dostuff
Call Askfordata
Call Crankonthedata
Call Printresults
Stop
End

But this just deferred the situation. The core of the work was in routine Crankonthedata, and it could be quite involved, with hundreds of lines of code. Sometimes I could break it up further, but there is a limit to "chunking" a problem. Sooner or later, you have to make it all go.

There was another technique I learned to rely on. As problems I needed to program got harder, it would take several days to write a routine. By such a time, I was pre-writing not the program code, but a flow chart of its operation, and spinning out the code for each block of the flow chart as I came to it. Inevitably, something would not work right, or I'd come to a section and find out I hadn't thought it through sufficiently; there were some dangling threads in the logic that I had to tie up. So at the end of the day, I learned to "grok" the whole routine I was working on, sort of hang the whole thing on a mental blackboard, and go to sleep on it. In the morning, I'd have a batch of stuff ready to write, and it could take half the morning to catch up.

By the way, I always wrote lots of comments in my code, something not all programmers do. Do you know why? I found out that if I looked at the routine just a couple of weeks later, I had no idea what was going on, unless I had good comments to help me decipher what I had written! All trace of the memory was gone. Somehow, a detailed memory, with thousands of parts, that I could hold onto for a few days, would still not make it into long term memory.

Perhaps that's a blessing. I wonder whether my brain would be full now, if I could remember every line of code I wrote over a forty year career. As I've written elsewhere, I used to produce 500-1000 lines a week of FORTRAN. With an average usable "year" of forty weeks (nobody works a 52-week year), that comes to a million lines of code or more.

I once met a pianist who claimed to be nothing special in the memory department, but he typically prepares for a concert by learning 100-150 pages of music. He performs strictly from memory. When he is getting ready for the next concert, any pieces he is not repeating have to be learned. The rest he mostly forgets, though he has a core repertory of a few hundred pages of music that he performs more often.

So what is working memory? It seems to be a forgettable memory store with a medium period, up to a few days or a couple of weeks. If things like FORTRAN code were stored as compactly in the brain as they are on a hard disk, my million lines of FORTRAN might total no more than fifty megabytes. These days, that's about a third of a square millimeter on the surface of a hard disk (the disk in my current computer stores 100 Gby per square inch, or 155 Mby per square mm). Somehow, we may store much more than this about many things, but not everything. I am awed.