Multi-store model

Multi-store model

1. How it works:

   • Atkinson and Shiffrin proposed that external stimuli from the environment first enter sensory memory (visual encoding) where they can be registered for very brief periods of time before decaying or being passed onto the STM store.
   • They believe that memory traces in the STM store are encoded in the form of sounds (acoustic encoding), and without rehearsal, the memory traces become fragile and are lost within about 30 seconds.
   • Material that is rehearsed is passed on to the LTM store where it can remain for a lifetime, encoding in LTM is assumed to be in terms of meaning i.e. semantic encoding.

2. Miller

   • Aim: To investigate the capacity of the LTM store.
   • Presented with strings of digits of increasing length that they had to recall immediately in the correct order (digit span technique).
     • Repeated with three-letter chunks of digits.
   • Participants were able to recall between 5-9 units of information.
     • Meaning short term memory could hold 7+/- 2 chunks of information at once.
   • Study has been repeated many times finding the same results - makes it reliable.

3. Peterson and Peterson

   • Aim: to test how long STM lasts when rehearsal is prevented.
   • Participants shows trigrams (a list of 3 letters e.g. QWE).
     • They were then given the distracting task of counting back in 3's from 300.
   • They where then asked to recall the trigrams.
   • Accuracy of trigram recall decreased as the amount of time spent counting increased.
   • If rehearsal is prevented, information vanishes rapidly from STM. Therefore decay is the mechanism for forgetting in STM.

4. Glanzer and Cunits Serial Position Curve:

   • Primacy-recency effect:
     • Serial position effect refers to the finding the recall accuracy varies as a function of an items position within a study list.
     • When asked to recall a list of items in any order (free recall), people tend to begin recall with the end of the list, recalling those items best (the recency effect).
       • Earlier list items, the first few list items, are recalled more frequently that the middle items (the primacy effect).
         • One reason for this might be that the primacy effect is the initial items presented are most effectively stored in the LTM because of the greater amount of processing devoted to them.
           • Where as the last list items presented are the ones still most fresh in the memory. They are still in the STM store so are also easily recalled.
     • 240 US army enlisted males.
     • Presented with a list of words, told to recall words in any order (free recall).
       • Experimental method used - IV - 2 conditions. Half pps recalled words immediatley after memorising. Half pps counted backward for 30 seconds before recalling words.
         • They found that delaying recall by thirty seconds destroys the recency effect causing recall of latter words to be similar to ones in the middle, however it does not influence the primacy effect.

5. Sensory store: holds huge amount of info, lasts fractions of a sec-3 secs.

   • STM store: 7+/-2 chunks of info, last roughly 30 secs.
     • LTM store: Infinate amount of info, lasts a potentially infinite amount of time.

6. Weaknesses of the MSM:

   • Rehearsal does not always lead to storage.
   • If encoding in STM is mainly acoustic then how do we understand language?
   • Some types of info are not amenable to rehearsal, e.g. smells.
   • The model is too simple and inflexible. Fails to take account of factors such as strategies employed for remembering things.
   • Places emphasis on amount of info processed rather than type of info.
   • Some things are easier to remember than others.
   • Criticized for focusing on the structure of the memory system at the expense of adequately explaining the processes involved.

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