Sunday, February 8, 2009

Human Memory

There are three basic activities associated with human memory viz. receiving new data from the environment followed by its processing and conversion into usable information within the brain; storing this information in the memory; and retrieving it as and when required.

Humans have three forms of memory. One is the immediate memory. Here one retains all details of an object or a scene or a picture for about 1/10th of a second like a batsman facing a ball. After that much is forgotten. Next is the short term memory where information is retained for a few minutes only. This memory is also known as working memory and has a limited capacity. It is also used for rehearsal, i.e. for mentally repeating the information over and over again so that it enters the long term memory.

The information which is stored in the long term memory can be broadly classified into four categories. First is the information related to specific tasks, which include riding a horse or a bicycle, driving a car, typing, painting, etc. These skills often require several years of experience to perfect. Secondly, the information related to fear-inspired actions like being bitten by a dog, getting hurt due to falling, getting a fire burn, etc. By proper training one can prepare oneself to take specific actions under difficult circumstances or emergency conditions. Third is ‘Episodic memory’, in which information regarding dated episodes or personal experiences is stored date-wise. Finally, the ‘Semantic memory’, relates to the use of words, grammar, metaphors, and all other details of language. However, these different groupings are conceptual in nature and no specific region of the brain as such is reserved for these categories.