Duration+of+Short+Term+Memory

DURATION !
 * Duration is the amount of time a memory lasts in out short term memory.**

The duration of Short Term Memory lasts up to about **18-20 seconds** and occasionally goes up to 30 seconds.

This was demonstrated in a experiment conducted by Margret and Lloyd Peterson in 1959. Participants were given were given trigrams these are (meaningless groups of three letters) to memorise. For example items such as qlg, jmb and mwt. Immediately after the trigrams were presented the participants were given a distracter or an interference task, where they required to starting counting backwards by threes from a three digit number for example: 634, 631 and 628. This was done to prevent rehearsal of trigrams. Following a time interval that varied from 3 to 18 seconds a light was used to signal that participants were required to recall the trigrams. As shown in the figure the figure below



The graph above shows the longer the interval, the less likely a participant was to accurately recall a trigram. By 18 seconds after the presentation of the trigrams, participants had forgotten almost all of the trigrams. When participants did not have to count backwards, their performance was much better possibly because they were rehearsing the items to themselves. In similar conditions if you repeat a telephone number over to yourself it can be retained in the Short Term Memory indefinitely. But if you look up a telephone number and then get distracted, you are likely to forget the number almost immediately.