Most people think that they forget slowly and surely, that the process is progressive and constant, that as time passes, the memory, rather like a leaking reservoir, empties out everything it has learned. But this a misconception.

The first experiments into the mechanism of forgetting were carried out by a German psychologist, Herman Ebbinghaus (1850-1909). He learned a meaningless list of syllables by heart and then noted how many he remembered after a few minutes, a few hours and then a few days. From these results, he worked out a graph, called the Ebbinghaus curve, which shows you how your brain really forgets what it had previously stored.

The putative (presumed) curve of forgetting shows the mistaken notion we generally have of the mechanism of forgetting. In reality, forgetting does not follow a linear path. It follows a logarithmic curve in slowing down: a rapid drop at first, and then a slower, more gradual drops with the passage of time. So we start forgetting soon after we've learned something. A few hours later, we can no longer recall 70 to 80 percent at will. The real curve of forgetting shows a very sharp curve

To fix data firmly in your memory you need to prevent the process of forgetting from setting in by starting to revise strating to revise straight away. This is what is called reinforcement time.

Ebbinghaus also understood that certain factors influence recall and forgetting. For example, we don't memorise a list of meaningless syllables and a poem in the same way. Hence, the kind of material to be recalled, its emotional charge, and the way it was learned (for example, the use of memorization strategies such as mental images and associations) all play a role in the retention of information.