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How Eigma decides you know something

Why a page you have only read stops at silver, what makes it fade once it is gold, and how Eigma chooses what to put in front of you next. The reasoning behind the colour on every page, worked out on your device.

Every page carries a colour, and the colour is the whole point of the product: it is Eigma’s estimate of how much of that page is actually yours. This page explains how the estimate is made, because a number you do not understand is a number you will not trust.

All of it is computed on your device by rules. No model is asked to work it out, so it costs nothing and needs no connection. (If you are signed in, the resulting numbers are part of what syncs between your devices, like the pages themselves.)

Two ways to raise a page, and only one of them reaches gold

A new page is grey. It becomes silver as you read it, and turns gold once you have started answering its questions. How brightly it burns is what tells you how well you answered: a page you got wrong sits at the dark end of gold, nowhere near the colour of one you have learned.

That split is deliberate. Reading is recognition: it feels like learning and it genuinely helps, so it moves the colour. But recognising a page you have read five times is not the same as being able to produce what is on it, so reading alone is capped. A page with questions on it can never reach gold by reading, however many times you open it.

GreyFiled, never opened.

SilverYou have read it. It brightens the more thoroughly you read, and stops short of gold.

GoldYou have answered its questions. Bright when you answered well and recently, dark when you did not.

The colour is a continuous scale rather than three steps, so a page sits somewhere along its stage's range and moves along it as you work.

The one exception is a page that carries no questions at all, such as a chapter overview. Nothing can be asked about it, so reading it thoroughly is all there is, and it can reach the top on reading alone.

Answering is retrieval, and retrieval is what makes a memory durable. Only a correct answer raises the durability of a page.

The reverse also holds. A page you have answered but never actually read is capped in the other direction: the Familiarity figure reaches 100% only for pages you have both read and been tested on.

Reading only50%

Answering only50%

Reading and answering100%

Familiarity weighs the two equally, so either one on its own stops halfway up.

The page itself shows one number rather than the machinery: a Memory state percentage, with Last tested and Last viewed beside it.

Fading

Memory decays, so a page left alone slides back down. Two numbers drive this:

How likely you are to recall it right now. This falls with time and is what makes a page come due.
How durable that memory is. This is what decides how slowly the first number falls, and it grows only when you answer correctly.

Re-reading a page you have been tested on recovers part of what you had forgotten, but only part: about half of the gap, and never all of it. This is why opening a gold page does not simply reset it to full, and why the way back to full is answering its questions again.

Spacing matters too. Answering the same page’s questions five times in one sitting does not make it five times more durable, because durability grows with the interval you actually recalled it across. Coming back tomorrow is worth more than going round again now.

One more thing moves a page: when new material is merged into it, or your assistant rewrites it, Eigma nudges it back a little, so it tends to resurface for review sooner. The text changed, so what you knew is no longer quite what the page says. Editing a page yourself does not do this.

What Eigma puts in front of you

The home screen sorts the active volume into three groups, and a page appears in at most one of them:

to read: never opened. Start here.
to recall: opened, but with questions still unanswered. This is the step people skip, and it is the one that makes reading stick.
fading: answered before, but slipping. Either the last answer was wrong or enough time has passed.

The Internalize tab is the same picture with the numbers: four figures for To read, Learning, Internalized and Familiarity, the spread of your volume across New, Learning and Internalized, a Familiarity by domain breakdown weakest first, grouped by top-level chapter, and the review itself.

Inside a quiz session

Start quiz on a page orders its questions weakest first: the one you last got wrong, then ones you have never answered, then ones that have decayed, and the ones you answered correctly most recently come last.

Questions share their page’s durability, so answering any of them tells Eigma something about the page as a whole. Each one you answer is another piece of the page you have proved you can retrieve, and a page counts as internalized only once you have been through all of them.