What Is the Forgetting Curve?

The forgetting curve is a graph that illustrates how we forget information over time. It was formulated in 1885 by Hermann Ebbinghaus, who conducted experiments on himself to understand how long the human mind retains information over time. Ebbinghaus discovered that we rapidly forget half of what we have learned in the first hour and that new material needs to be reviewed over time periodically to be stable in memory. The Ebbinghaus forgetting curve was a pioneering step forward in understanding human memory.

Ebbinghaus was one of the foremost psychologists of his time, who utilized scientific processes to study the mind's ability to retain and forget information. He used himself as a test subject and started experimenting with his own capacity to recollect information by creating a set of 2,300 three-letter, meaningless words to memorize such as "zof." His objective in choosing these words was to find out how well he could remember information that had no meaning or relevance to him in any way. He studied multiples lists of these words and tested his recall of them at different time intervals over a period of one year.

The results of his experiments gave the scientific community numerous insights into the exponential nature of memory retention. The formula for it is R = e^(-t/s), where t and s stand for time that has passed since learning and memory strength, respectively, and R stands for memory retention. He published a paper that described the forgetting curve in 1885 titled "Memory: A Contribution to Experimental Psychology." The results of the experiments were plotted to form the Ebbinghaus forgetting curve, which revealed how information is forgotten over time. This curve is also known as the Ebbinghaus curve of forgetting, the Ebbinghaus effect, and the Ebbinghaus forgetting function.

According to his findings, people forget 40 percent of what they learn after the first 20 minutes and retain only 30 percent of the information after six days. After a period of time, the forgetting reaches a plateau, and the rate at which people forget becomes slower. This indicates that the data stored in long-term memory is relatively stable. Ebbinghaus also discovered how repetition increases the amount of information retained and how every repetition increased the time interval before the next repetition was needed.

His pioneering research unveiled many other insights into the nature of memory. He uncovered how difficult it is for the mind to retain information that has no real meaning for a person. He also showed that a person can have greater success with improving recall if the review of the new material is spread out and that it is easier to relearn material the second time than the first time. Though this research is very old, the insights put forth by the Ebbinghaus forgetting curve are still utilized by psychologists today.