STM and LTM: capacity, duration and coding

what is capacity?

the amount of information the memory store holds

capacity of the STM

research suggests STM capacity is limited to 7+ / -2 items (or between 5 and 9 units). when new information comes into STM it pushes out the old information (displaces) due to this limited capacity

capacity of the LTM

research suggests that the capacity of LTM is unlimited. as capacity of the LTM is notoriously difficult to measure, there is very little research in this area.

what is duration?

the length of time the memory store holds information

duration of the STM

research (such as that conducted by peterson and peterson) has suggested that information can only be held in STM for a limited period of time (18-30 seconds). however, this can be extended through rehearsal (i.e. repeating information over and over again)

duration of the LTM

research suggests that duration of LTM is potentially unlimited (can potentially last up to a lifetime). even if information cannot be retrieved that does not mean the information is not stored in LTM

what is coding?

the way information is processed so it can be stored in memory

coding of the STM

research suggests that encoding in STM is mainly acoustic ( i.e. by sound). when a person is presented with a list of items to remember, they will try to hold them in STM by saying them over and over out loud

coding of the LTM

research suggests encoding in LTM is mainly semantic (by meaning). we need to understand something (process its meaning) for it to be retained in LTM