How many events, stories and facts do people really remember? I decided to do a very crude experiment. From a complete list of vocabulary words, I generated sets of word triples (Noun, Verb, Noun) such as:

1 clarity consider sonnet
2 letterman propose tapdance
3 assignment deduce senate
4 virtuoso weaken ferment
5 controversy jeopardize globe
6 dialysis recur rooftop
7 dislocation admit portal
8 swirl decrease bough
9 dolphin install compatriot
10 gust beware extrapolation

There are about 200 billion possible triples. I seem to be able to assign an obvious word triple to almost anything I remember. But in a random set of 1000 triples, I didn’t see any that obviously described a memory. I decided to cut back the experiment and just generate pairs of nouns:

1 lunch clarity
2 fist sonnet
3 letterman gamble
4 tapdance assignment
5 ounce senate
6 extrapolation mast
7 ferment controversy
8 yip globe
9 dialysis artisan
10 rooftop dislocation

There are 100 million possible pairs from my vocabulary set, and I’m looking for clear associations with memories, like “kennedy assassination” or “birthday party”. Out of a random sample, about 2 percent could be associated in such an obvious way with a memory. If every memory could be assigned a fairly obvious word pair, then this implies that I only have about 2 million memories.

That’s a surprisingly small number. I’m pretty skeptical about this experiment, and I’m sure we can find countless flaws in the whole concept of it. But it is amusing and suggests a contrary notion that the human mind might be far more limited that we like to believe (and we all know how much I enjoy contrary notions).

One obvious flaw is that meaningful word pairs might only number in the millions, but could refer to hundreds of different memories. So I tend to conclude that people have somewhere from 1 to 100 million memories.

Another approach to estimation of long-term memory capacity is to note that people only live for about 30,000 days. How many events per day really stand out enough for people to remember them permanently? That makes it easier for me to believe that people only have on the order of a million memories.

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PS. I haven’t been posting a lot to my blog, because I’ve been putting my thoughts on Facebook notes. (http://www.facebook.com/profile.php?id=506882584). Folks are welcome to send an add request, but I can’t guarantee I will accept requests from strangers, unless they have a real Facebook page that let’s me know who they are.

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