How quickly you forget

memory 1How quickly you forget depends upon several factors



The Ebbinghaus Law of Forgetting

Forget ebbThe forgetting curve hypothesizes the decline of memory retention in time. This curve shows how information is lost over time when there is no attempt to retain it.

The stronger and the more emotion that is attached to the memory, the longer period of time that a person is able to recall it. A typical graph of the forgetting curve purports to show that humans tend to halve their memory of newly learned knowledge in a matter of days or weeks unless they consciously review the learned material.

The forgetting curve is impacted by both:-

‘Cognitive ease’ – if you have heard it or seen it recently it is easier to recall and retrieve , so the more frequently you visit a subject the easier it to recall the subject and support matter.

‘Emotional impact’: [Daniel Kahnman]. What you were doing, thinking or feeling while or just before you tried to remember the subject matter.

In 1885, Hermann Ebbinghaus worked out the basic exponential nature of forgetting. He suggested the following formula to represent it:



where R is memory retention, S is the relative strength of memory, and t is time. The strength of the memory is S = I x V x R [intensity x vividness x repetition]

Hermann Ebbinghaus did self-experiments where he memorised nonsense syllables, such as “WID” and “ZOF” by repeatedly testing himself after various time periods and recording the results. He plotted these results on a graph creating what is now known as the “forgetting curve”.

Ebbinghaus also developed the concept of “overlearning”. If you practiced something more than is usually necessary to remember it, you would have effectively over learnt it. Overlearning ensures that information is less likely to be lost or forgotten, and the forgetting curve for this overlearned material is shallower.

Ebbinghaus outlined that the base forgetting rate differs little between individuals. He also suggested that the speed of forgetting is affected by factors such as the difficulty of the learned material and its representation (e.g. is it abstract or does it have meaning), physiological factors such as stress and sleep also affect retention.

Ebbinghaus also found that how quickly you forget is impacted by:-

Better frequency

the more frequently you review the information the more retention. It moves from the conscious competence to the unconsciously competent content. Spending time each day to remember information, such as that for exams, will greatly decrease the effects of the forgetting curve. Reviewing material in the first 24 hours after learning information is the optimum time to re-read notes and reduce the amount of knowledge forgotten. There is also evidence that if you review material more frequently, you will ‘like it more’ – too and this also aids memory.

Better memory representation

(e.g. with mnemonic techniques) – for example the 5E’s, PESTEL, 7C’s of knowledge

A rhyme

like “Little strokes fell mighty Oaks” is easier to remember/ recall and will be remembered for longer than “Little strokes fell big trees”


based on active recall (esp. spaced repetition). Revisiting concepts and asynchronous learning via video, quiz or self-challenge. Active recall is a principle of efficient learning. It contrasts with passive review, in which the learning material is processed passively (e.g. by reading, watching, etc.). For example, reading a text about George Washington, with no further action, is a passive review. Answering the question “Who was the first US President?” is active recall. Active recall is very efficient in consolidating long-term memory.

Emotional impact

There is evidence that Emotional impact effects remembering: for example, shocking events such as the Kennedy Assassination or 9/11 are vividly imprinted in memory (flashbulb memory).


There is quite strong evidence that your mood influences your cognitive ability to recall. Spending 5 minutes thinking about a happy event before reviewing the content you want to recall and remember will greatly aid memory.

What are you doing to actively remember the things you learn every day –?

Do you have a – “what I learned today log” – Key fact and figures and interesting facts

How often do you revisit the stuff you learned last week? Remember the 10,000 hour rule if you want to be world class – Attitude, Skills, Knowledge

And remember there is always Morethan1answer…