Holes in one’s memory

Not everything we learn sticks.  This can be discouraging.

Our consultant who tutors math and science is now facing a number of discouraged students.  From the beginning of the school year they have worked hard to master the basics of trigonometry, a quite arcane field to most of them, and they’ve been pretty successful at it.  But now, after their math course has concentrated on other things for a few weeks, they’ve gone back to study for a test and found that trig is somehow unfamiliar.  Most remember that they knew it once, but the hard-won skill seems to have evaporated.  “How can I really learn it, and keep from forgetting it again?” one asked in near-despair.  We’ve said before that the very process of learning, even if it’s not permanent, has some use; but these students are facing tests.

None of us is a specialist on memory, or the processes involved in learning.  But we have all learned things, so we have some observations.

The best way to remember something is to keep using it.  Trignometry is firmly embedded in our heads because we’ve continued to employ it in calculus and a multitude of scientific problems; instead of a subject in itself, it’s a tool to use in other work.  But it’s not really possible to stay active in everything you learn, and (as these students have found out) a new accomplishment can fade quickly when your attention is elsewhere.

So we have to relearn things.  The second time around is easier.  That’s not obvious to these students, facing a repeat of their earlier effort.  But our astronomer, in particular, has seen this several times.  Returning to his grad school notes on a subject after working on other things for a couple of years, he was struck by how someone was able to imitate his handwriting so well, so strange did the material seem.  But after a bit of study things started to come back, and he was forced to admit that it was his own writing.  Eventually he had assimilated it all again and was correcting mistakes he’d made in the notes.  Relearning, if pursued with diligence, goes faster and deeper and stays longer.

The next time around (if there is one) can be surprising, as something we thought was long-lost comes back quickly and more completely.  We’ve seen this ourselves, not long ago.

We’re not sure how many times it takes until a subject is firmly set in our memory.  No doubt it varies widely from person to person and subject to subject.  But we suggest an experiment: take something you learned long ago in school, but haven’t used since.  Find your class notes or textbook (though it’s unlikely you’ve kept either), or another book or online course or whatever.  How long does it take for the strangeness to wear off?  Do you understand more the second time around?  Do you remember it longer?