All information present in consciousness is allocated in a temporary repository called short term memory. This storage is very limited. According a classic psychological experiment managed by George Miller (MILLER, 1956), the number of the items an average human can hold in short term memory is seven plus or minus two.  The items can be words, pictures, letters, numbers, it doesn´t matter: this kind of memory can´t save many things. If the temporary storage is full, new information can not be processed and, like the computer RAM memory, the process become slow and fail completely. So, it is impossible keep in mind much information and the repository needs to be emptied to enable another information entry. To sustain the information in the consciousness it is necessary, in this way, dismiss irrelevant informations. In other words, forget secondary details is required to validate main ideias.

Beyond the temporary repository, the information can be consolidated and stored for longs periods of time in a long term memory. Even though in this system the data can be remembered for days, months, years or even decades, not all information is always available. In fact, the biggest part of the memories is easily forgotten over time. Almost all long term memory is erased over and this means that this kind of memory is not permanent. This forgetting process is essential to organize and promote the main memories, like the computer ROM memory. Clinic cases of patients who never forgot nothing (a syndrome called hypermnesia) show this perfectly. Solomon Shereshevsky was the most famous of this cases. Described by A. R. Luria (LURIA, 1986), Shereshevsky never forgot anything and was able to recall a speech word by word twenty years after, for example. But his prodigious ability lead to several problems: he was unable to block unwanted memories, he could not recognizing faces because they looked different from the past and the he could not understand abstracts concepts or generalizations. The inability to forget lead to an inability to remember properly. So, also in a long term ways, forgetting improve memory. 

Furthermore, we are what we remember and also what we forget. Personal identity is formed by autobiographical memory. But not all facts and events of live contribute positively to self-esteem and well-being. So, the researchers have found that this kind of memory has a positivity bias: “the tendency (...) to recall more pleasant memories than either neutral or unpleasant other” (ANDERSON, 2009, p. 266). In fact, negative events were not recalled as much as positive events and this effect improve the well-being. Curiously, the positivity effect is increasing over the lifespan. Forget bad and neutral memories makes the good memories strong and stronger good memories help us to cross the course of human life.

As essential as to remember is to forget. Short term memory is limited, so it is necessary forget insignificant data. Long-term memory is not permanent, so only strong information remains. The positivity effect change our memory, so it is good for self-esteem keep the good memories. Thus, if you have lapses and this lapses do not affect deeply your life, do not worry about it as my grandmother worried. Do you want remember? So forget it.

ANDERSON, M. C. Mottivated Forgetting. In: Baddeley, A., Eysenck, M. W., & Anderson, M. C. (2009). Memory. East Sussex.

LURIA, Aleksandr Romanovich. The mind of a mnemonist: A little book about a vast memory. Harvard University Press, 1968.

Miller, G. A. "The magical number seven, plus or minus two: Some limits on our capacity for processing information. Psychological Review. 63 (2): 81–97, 1956