The Forgetting Curve

Updated: Apr 30

We lose about 90% of the information we learn within a month. So you may be investing a lot of money into learning a new skill or training your workforce, when ultimately not much of the material is remembered. The brain tries to remember important information for survival, for example, if you accidentally touch a flame you automatically retract your hand. To retain other types of information we must persuade our brains that the information is worth remembering and thus overcome the forgetting curve.


Well-designed Simulations and Serious Games can be powerful learning tools because they effectively combat the forgetting curve. The forgetting curve, discovered by nineteenth-century German psychologist Hermann Ebbinghaus, explains some of the fundamental factors that can make learning and remembering difficult. He tested his memory by learning lists of nonsense syllables, such as “WID” and “DIF” and attempted to recall the syllables at particular points in time. Within a few days he had forgotten most of the information and therefore concluded that memory quickly decays.


Subsequently Ebbinghaus created the forgetting curve which shows the rate of forgetting after learning:

  1. The curve is exponential in nature which means that memory sharply drops from 100% to below 50% in the first few days. Some psychologists say this drop can even occur within the first hour after learning.

  2. The forgetting rate then continues to decline but at a slower rate.

  3. Until it plateaus, which was discovered when Ebbinghaus remembered some syllables on one day and then recalled the same syllables on consecutive days.

The basic forgetting curve looks like this:

Factors affecting retention

The forgetting curve can be displayed by this equation:


R = e^(-t/s)

  1. R – retention is how easily information can be recalled

  2. t – time passed since the learning has occurred

  3. s – strength of memory

  4. e – Euler’s number


Retention depends on:

  1. The memory’s strength – stronger memories are easier for individuals to recall after longer periods of time compared to weaker memories. Individuals differ in their memories’ strengths.

  2. How much time has passed since learning – people tend to forget 90% of what they have learned within a few weeks.


Rate of forgetting

The speed of forgetting information can be affected by numerous factors:

  1. Complexity of the material – the more complicated information is, the quicker it will be forgotten

  2. How the material is taught – for example, using visual aids, audio, essays, slideshows etc

  3. How meaningful the information is – this is the extent you can link your learning to previously known concepts. The more relatable the information is, the slower the rate of forgetting

  4. Physiological factors – such as, lack of sleep or hunger

  5. Psychological factors – for example,  stress or anxiety


By adding spaced repetitions of learning (i.e., relearning repeatedly over time, with gaps between the sessions), the forgetting curve can instead look something like this:

Unfortunately , little research has been done on the impact of Simulations and Serious Games on the forgetting curve. However, when we examine the various principles that underlie the forgetting curve, we can clearly see that Simulations and Serious Games are an ideal technology for maximizing learning retention.

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