capacity

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STM is very limited in storage capacity compared to sensory memory and long term memory. Rarely are we abel to hold more than between 5 and 9 bits of information in STM at any given time regardless of the nature of that information. The limit of STM is described as having a range of 7__+__2 items of information. =====

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Estimates of the capacity of STM are obtained by asking research participants to memorise simple lists of data of different lengths; for example randomly ordered numbers, letters, nonsense syllables or unrelated words. the length of the list that the participants can recall half the time is considered to represent the capacity of short term memory. =====

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Space in STM is filled when we think and when information is temporarily brought from LTM into working memory to be used or updated.This is why you cannot remember the telephone number you have just looked up if you begin thinking about what you might say before you dial the number. =====

==== Information stored in STM is lost primarily through decay (not being used) and displacement (being pushed out) by new information. Decay of information in STM occurs when you forget what you want to say in a conversation while you wait for another person involved in the conversation to finish what they are saying. Your thoughts quickly fade from STM because listening to what the speaker is saying prevents you from rehearsing and therefor maintaining in STM the point you wanted to make. ====

==== It is difficult for us to think about problems involving more than 7__+__2 issues (items). We forget some aspects of the problem because they exceed the capacity of STM. in such situations, writing down all the points to be considered prevents the information from being lost while the central excecutive in your working memory is focused on another aspect of the problem. ====