How long does short-term memory last?

Typically, short-term memory lasts for no more than 20 to 30 seconds. Short-term memory holds approximately seven items at one time. Some information is too large for the short-term memory to hold, which causes only pieces of the memory to be transferred to long-term memory.

An example of information that is too large for the average person's short-term memory is a long phone number. Repeating the number every few seconds resets the short-term memory clock, making the number memorable for a longer span of time. Information that is used or repeated on a regular basis is more likely to be stored in the long-term memory.