Multi Store Model

Multi Store Model

1. LONG TERM MEMORY

   • DURATION
     • the duration of LTM is around 48 years.
       • Bahrick et al used ps ages 17-74 to free recall high school classmates names, identify names and faces from their yearbook.
         • after 15 years names and faces were 90% recalled after 48 years names recalled was 70% and names were 80%
     • study was not artificial so it has high external validity and result apply to real world.
     • some variables were not able to be controlled e.g. ps may have looked at their yearbook after leaving school so the memories are fresher.
     • as the memories has significance to the ps it cannot be assumed that the same applies to other information such as school subjects.
   • Encoding
     • LTM encodes semantically, based on the meaning of words
       • Baddely gave ps a list of words semantically similar, acoustically similar and semantically dissimialr and asked them to recall the words 20 minutes later.
         • the ps recall was worse on the semantically similar than the dissimilar lists therefore suggesting that LTM encodes semantically
     • the study was well controlled so there is confidence in the results and it has high internal validity.
     • the findings themselves are plausible
     • the study was artificial and therefore lacks external validity so we cannot be sure that it applies to real life.
   • Capacity
     • the capacity of LTM is thought to be unlimited.

2. SHORT TERM MEMORY

   • Encoding
     • STM encodes acoustically, based on the sound of the words
       • Baddely gave ps lists of words acoustically similar, semantically similar and acoustically dissimilar and asked them to recall the words immediately
         • ps made more mistakes recalling the acoustically similar words suggesting that stm encodes acoustically
   • Duration
     • the duration of STM is less than 18 seconds.
       • Peterson and Peterson used trigrams and asked ps to count back in 3's for 3-18 seconds and then asked them to recall the trigrams.
         • the longer the time delay the poorer the recall.
     • the experiment was well controlled as the trigrams had no vowels meaning that no words could be made from them
     • the stimuli was completely meaningless and artificial and therefore lacks external validity and STM may not be as short in real life
   • Capacity
     • the capacity of STM is 7+/-2 chunks.
       • Jacobs used a digit span task and found that the capacity of STM is 5-9 digits.
       • Miller put forward the idea of chunking information and that STM can hold 7+/-2 chunks
         • Simon supports Millers findings but also suggested that the size of the chunk must be taken into account as larger chunks are more difficult to rehearse.
     • as Miller and Simon agree on the figure and the experiment was well controlled it gives us confidence in the findings.
     • all 3 studies can be criticised as they all lack external validity

3. GENERAL EVALUATION

   • the MSM is an improvement on previous models as it shows STM and LTM as different stores.
     • support from patient KF, he was in an accident and his LTM was fine but his STM was damaged.
     • research has shown STM and LTM to have different capacities/durations/encoding
   • the model is over simplified. A later model has shown STM to have more than one store which the MSM doesnt account for
   • according to the model, rehearsal is how information is transferred from STM to LTM which seems unlikely as we spend little time rehearsing and so processing may be an explination.