08 December 2013

Memory schedules and the danger of the hard line

Spaced recognition systems (SRS) have become very popular in the computer language learning community as a means to learn and revise vocabulary and phrases.

Spaced recognition is essentially just flashcard software, but flashcard software backed with an intelligent algorithm that attempts to find the optimally efficient timing to aid your memory.

This timing all arises from the idea of "memory schedules" put forth by people such as Paul Pimsleur, who gave his name to a popular series of cassette-based language courses in the 1960s (a series which continues to be published to this day with virtually no differences to the basic structure).

The first principle behind these memory schedules is that new information is gradually forgotten, and needs to be reminded. (So far, so obvious.)

The second principle is that the better learned something is, the longer it takes before being fully forgotten -- the memory pattern is stronger. (Also obvious.)

Taken together, these principles give the basic form of memory schedules: revise the item to be remembered just late enough so that it's not forgotten, at progressively longer intervals.

Now this of course is obvious, and all teachers schedule their revision along similar principles. The real promise of memory schedules is the ability to get a measurable and verified number on it.

So the hard liners within memory schedules did put figures in place, completely ignoring the fact that some things are more difficult to remember than others -- for example, memorising the full 10 or 11 digit phone number for someone in a foreign country is going to be harder than memorising the number of your neighbour, whose number will probably only differ from yours by 3 or 4 digits.

The numbers, therefore can't be right, which is why more recent memory researchers have been looking for formulas that can take into account complexity. And as it's hard to objectively measure that complexity beforehand, very sensibly, SRS tries to work it out for each item to be learned as they go, based on the learner's performance. That's a good compromise.

But there's another claim from the hardliners that's really very hard to stomach: the claim that nearly forgetting and then reminding makes for a stronger memory trace. Than what? Than revising it more frequently.

Less revision = better learning...?

That is a weird claim, and the guys that claim it must presumably have data to back it up, but I just can't see how it can be a generally applicable truth.

What is definitely true is that excessively frequent repetition can keep something in short-term memory without ever forcing it to be stored in, or recalled from, long-term memory; and something that isn't in long-term memory isn't learned. Worse: if you are really frequent in your repetition, you can hold the information in working memory, and never have to recall it at all.

This is, of course, a problem that should be familiar to most language teachers and learners. The first hour of language instruction is often very light. In a one-hour introduction to Finnish, I was taught to say "good morning", "how are you?", "I'm fine,", "what is your name?", "My name is...", "what is it?" (or maybe "what is this?" or "that?"), "it's a..." and 6 or 8 proper nouns (including "car", "key" and "aeroplane"). I forgot everything except "good morning" and "key" within about 24 hours. I now only remember "good morning". Everything was repeated too quickly, so nothing went into long-term memory.

But that is not to say that repeating at the very last minute is the correct answer, and this flies in the face of a lot of material on memory anyway, and particularly in terms of language.

There is a simple rule in memory: the more often you are called on to recall something, the quicker and easier it becomes to recall. To use a trivial example, "is" is far quicker to recall than "carbunkle", because we use "is" every single day of our lives. (Or the equivalent in our language, if not English speakers.)

If not reaching that threshold of "nearly forgetting" inhibited better memorisation, then we would be in the paradoxical situation of knowing words we almost never say better than the words we say every day, but I have never said "what's the word... it's on the tip of my tongue... oh yes... is." It just doesn't work that way.

So no, SRS isn't the optimal way to remember individual items, but it's certainly a pretty efficient way to learn a bulk load of items.

It's good, but it doesn't deserve the hard line.


Anonymous said...

Re complexity, there are other principles, articulated on the following page for formulating knowledge:


What one finds there is an admonition to break up complex knowledge into smaller chunks, the smaller the better, and learn them individually rather than as a whole. The problem though with things like long excerpts of literature, poems, etc., is that for you to be able to piece them back together, you need a "pointer" (which folks with experience in programming will understand).

That is, a connection to the previous or next element or both. So one would learn a little bit of the previous chunk along with the new one (kind of similar to a journey type of mnemonic device). As for something really abstract like a 1000 digits of pi or the like, I am not sure how this could be formulated for SRS.

Another important aspect of SRS is that typically one learns a body of knowledge like the vocabulary of a language for a purpose, such as to use that language, and by extensive exposure reinforces the individual elements, although obviously it takes massive exposure to to reinforce the less frequent items. I am not sure how any postulated ideal SRS schedule can take such outside exposure into account.

BTW, have you ever tried to beg your way back into HTLAL? Supposedly one can contact a moderator and request to be allowed back, though possibly only with a new account.

Best wishes.

Nìall Beag said...

You're at risk of pulling me off at a bit of a tangent -- I wasn't criticising SRS per se, simply using it to start discussing the danger of taking a hard line on anything. SRS is clearly pretty effective, and I use it myself intermittently.

But just because something works relatively well doesn't mean that the principles behind it are correct. Take as another example Tai Chi. A lot of people derive a lot of health benefit from performing the physical exercises, and therefore Tai Chi is a good thing. Unfortunately, a lot of those people who do benefit from Tai Chi are likely to believe the principles underlying chi -- mystical energy flows and the like -- despite the fact that science has moved on in the centuries following the origin of the art.

If you can accept any technique without buying into the hard line, you're far more open to refine and improve the technique based on experience and observation.

If you buy into the principles, however, you can head down a dead-end by focusing on the principles as the only directing force for improvement.

Nìall Beag said...

Anyway, going down that tangent...

There are problems with SRS, and Dr Wozniak skirts around them. Essentially, what knowledge is atomic? Very little -- most true learning is structured and related, and SRS does not and cannot capture that.

Take for example under 17 "Redundancy does not contradict minimum information principle" where he discusses passive/active. Are these not linked? How can we learn the knowledge as a single memory trace if we learn parts of it as a single atomic unit?

Does it not show a weakness in technique if learning knife->sgian doesn't also allow us to recognise sgian->knife...?

And as to HTLAL, I'd love to be back on it, but it's not too important to me at the moment, and might still end up as a time sink when I've got more important things to do... some of which involve precisely those problems I see in SRS...

Anonymous said...

Thanks for the replies. I realize that you were not criticizing SRS, and neither was I criticizing your discussion of it, rather I merely brought up a couple more points as to the complexity of SRS, which if anything to me indicates you are likely correct in not buying into the whole "hard line" as you call it.

Indeed with Anki specifically, while I am grateful that such a wonderful program is available for free (and hopefully a small donation), I am not really interested in the "hard line" that the developer seems to take in trying not just to urge, but sometimes to force, users to use it in the way he thinks is best. His non-expert opinion/interpretation of SRS theory, is just that of "some dude on the internet", the same as with my own interpretation.

Because of additional exposure that I mentioned outside the use of any particular SRS system, it seems difficult to impossible to have rigourous enough controls to test adequately.

Re HTLAL, I was curious if you had actually asked to be taken back and been rejected, or just had not bothered to do so.

Best wishes again, and now I will read your latest postings.