The Curve

Forgetting

Curves are great when they're working for us: the power of computer processors doubling every year and a half, compound interest on our savings. Unfortunately curves also work against us, we speak of "steep learning curves" and, of particular interest here, the forgetting curve.

Forgetting Curve

fig. 1 - The Forgetting Curve

The forgetting curve shows us how much we forget over time. We spend time and effort trying to fix things in our memories but inevitably those memories fade. Just how much and how fast they fade is a very good question, one that for today we have no absolute scientific answer. This should not discourage us, in fact we know a great deal about the characteristics of our memories.

There are many factors that influence our ability to remember: time of day, our age, environment, how well we know and understand the context of our material, our perceived importance of the information, as well as many others. We all have experience in trying to remember things so we know that one of the most powerful memory techniques is simply to repeat it. We also know how boring and inefficient this feels, unsurprising really as mostly we go about things the wrong way.

To see why Mindburn works let's take a closer look at the forgetting curve. In particular look at what happens when knowledge is reviewed for the first time.

Spaced Repetion Graph

fig. 2 - Spaced Repetitions

 

  • The curve starts at the top left, this is the time of first study, we know the material 100%.
  • As time passes we gradually forget, at point two for instance we have forgotten half of our material after the first day.
  • Time for our first review! Our knowledge goes back up to 100% as we re-learn the material.
  • Again after we have reviewed over time our memory fades, but this time there is an important difference: the forgetting curve is flatter, we are forgetting less over time - here around 40% after a week.
  • More reviews successively flatten the forgetting curve until it is practically a straight line which means the knowledge is as good as permanently burned into our memories.
(Note that the scale on the time (x) axis is logarithmic - the intervals become longer.)