How short term memory works

Eugen G Tarnow  August 3 2011 10:35:11 AM

1.  It takes 0.5 to 3 seconds to put a word in your short term memory by looking at it or listening to it.  This "activation" time scale roughly corresponds to the time scale of synaptic exocytosis, i.e. the time it takes to have all the messenger molecules released from the "presynaptic" side of the synapse.  The activation time is longer for items that are complex than for items that are simple.

2.  If you are not taking in very much information, it takes 3 seconds to 15 minutes to lose a short term memory.  It "decays" relatively slowly with time (logarithmically).  The time scale and functional behavior is roughly the same as for synaptic endocytosis, i.e. the time it takes for the presynaptic side of a synapse to heal back up and recreate the containers with the messenger molecules.

3.  The more information that goes into your short term memory, the faster this information decays.  So, for example, if you are asked to read one word every 5 seconds, this word will remain longer in your short term memory than if you are asked to read one word every second.  In both cases the short term memory decays.  Contrary to popular opinion one memory item does not replace another memory item.  A possible explanation for this "presentation rate" dependency is that some catalyst is generated the more memory items are activated and this catalyst speeds up the synaptic endocytosis which makes the memory disappear faster.

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