Short term memory (STM) has a capacity of 7+-2 items (Miller, 1956) and long term memory (LTM) has a potentially unlimited capacity. STM encodes acoustically (sounds) whereas LTM encodes semantically(meaning). Finally, STM has a duration of 18-30 seconds whereas LTM is said to have a potentially unlimited duration.
Sorry if this is a little different to what you've learned in school I assume you're doing GCSE psychology, I did AS.
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