Rough Simulation of SRS vs. Traditional Review

So, what the hell is exactly going on in this video? (I'll start by saying that this video is about a certain flash-card/review methodology for remembering information, so if that bores you, stop reading here.)

Lets first go over a little bit of information on memory. Imagine your mind consists of a whole bunch of rechargeable batteries, which can each be fitted with some factoid. However, after storing the factoid, the "battery" slowly discharges, until eventually it runs out. At that point, you've forgotten the factoid.

However, luckily, you can recharge that "battery". You can do this by reviewing/relearning the factoid again at another point in time. This is part of a methodology known as "Spaced Repetition" studying.

Another useful feature of these "batteries" is that every time you recharge them, the amount of time it takes for them to discharge increases. After recharging (relearning the information) many times, you'll remember that information for a very very long time.

An SRS (Spaced Repetition System) is a specific type of flashcard method that tries to improve your memory of facts, by making sure that all of your "batteries" stay charged. It can be estimated as to how long it'll take for you to forget a fact, based on how many times you've successfully reviewed that fact. The SRS will make sure that you review facts right before you forget them, but no sooner.

In this video, I threw together a rough simulation of what a map of someone's memory might look like... the memory of someone using traditional random studying, and one of someone using SRS.

The simulation presented is by no means scientific or accurate. A large majority of it runs on approximations and educated guesses... but it should give you an idea of how SRS works on your memory. It's meant more as an illustrative model, rather than a concrete simulation.

The video shows a grid of factoids, where new factoids are being presented at a constant rate. Over time, the factoids begin to fade to black... the closer they get to black, the closer they are to being forgotten. However, if they're "recharged" by being relearned, they advance up a tier (represented by the color and number of the cell). The higher the tier, the longer it takes for the factoid to be forgotten. If at any point, a factoid gets completely forgotten, it is sent back down to the lowest level.

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Technical Details:

In our traditional model, the algorithm works as followed:

-Our human will review factoids at a 100% chance when they're first presented. However, the longer the human has known the fact, the less likely they are to be motivated to relearn it. Eventually they stop reviewing it completely, hoping that it has been permanently committed to memory by that point.
-The human can choose to restudy the factoid whenever they desire. However, if they review it again only 10% of it's lifetime after it was last reviewed, that will be counted as part of the same review. (As if they took a short break, and went back to studying; rather than having two separate study sessions separated by a reasonable gap of time) In any other case, it'll be promoted to the next tier.
-The order that the human studies the factoids is random, and is based purely on the probability of that factoid being studied (ie: how recently it was initially taught to the human)

In our SRS model, the algorithm works as followed:

-Our SRS will present a factoid to our human if it is 75% of the way towards being forgotten, or if it is a brand new factoid.
-SRS are known to have an approximate 90% retention rate... so 10% of the time, our human will forget the fact, when its presented.
-Our SRS will not present a fact at any time sooner than the 75% forgotten mark. So much so that the human in this rule set is not allowed to review a factoid before it is presented.
-And of course, it's assuming that the human is reviewing his SRS every single day, making sure to go over everything that's due! (Heh, that's the catch with SRS systems... gotta keep up with your studies :D)


Obviously there are many ways this simulation can be improved, and made more accurate.

Category:

Education

Tags:

• Studying
• Review
• SRS
• Flash
• Card
• Lietner
• Forgetting
• Curve
• Anki
• Memory
• Spaced
• Repetition

[emxhc]

i'd love to see this kind of visualisation with anki or other SRS software. shouldn't too be too hard to implement either. maybe if you could click on individual facts as displayed so you could see which were the ones you were forgetting so much...

shame this video was not scientific, it seems somewhat biased towards SRS cause I am certain that I forget much more often with SRS than this video suggests.

[AndrewFMs]

@emxhc Yeah, it definitely is a loose representation. For example, one thing it doesn't take into account is that brand new facts entered into the SRS not only tend to be forgotten more quickly, but also more frequently. It might take like 3-5 reviews to actually get a new fact from 1 - 2.

[HackingChinese]

This is the coolest thing I've seen for quite a while! I usually try to introduce SRS to students and it works most of the time, but having a visual representation like this to complement the words is really awesome. Thanks!

[aTOH]

This is incredibly neat!