Table 1

It is a common experience to forget what one has learned. Usually, forgetfulness increases with with the length of the retention interval, the time elapsed since the material was last studied or thought about. A graph of the amount remembered (as measured by tests of recall or recognition or relearning) as a function of increasing retention intervals produces a forgetting curve, the slope of which represents the overall rate of forgetting. The first forgetting curve was published in 1885 by Hermann Ebbinghaus, the pioneer in the scientific study of memory. His curve showed the now-familiar monotonic and negatively accelerated form, where the momentary rate of forgetting decreases over time.

Trace Decay

Perhaps the earliest and simplest attempt to account for forgetting was the idea of trace decay, which postulated that memorizing something lays down a neurochemical imprint or record in the brain, called a memory trace or engram...