Forgetting curve

The 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. A related concept is the strength of memory that refers to the durability that memory traces in the brain. The stronger 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 supports one of the seven kinds of memory failures: transience, which is the process of forgetting that occurs with the passage of time.

History

In 1885, Hermann Ebbinghaus extrapolated the hypothesis of the exponential nature of forgetting. The following formula can roughly describe it:

where is memory retention, is the relative strength of memory, and is time.

Hermann Ebbinghaus ran a limited, incomplete study on himself and published his hypothesis in 1885 as Über das Gedächtnis (later translated into English as Memory: A Contribution to Experimental Psychology). Ebbinghaus studied the memorisation of 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". From his discovery regarding the "forgetting curve", Ebbinghaus came up with the effects of "overlearning". Essentially, if you practiced something more than what is usually necessary to memorize it, you would have effectively achieved overlearning. Overlearning ensures that information is more impervious to being lost or forgotten, and the forgetting curve for this overlearned material is shallower.