Multi-store model of memory

• Introduction to the MSM

  • The Multi-store model of memory is a theoretical model of memory developed by Atkinson and Shiffrin. 
  • It includes 3 separate unitary stores: The sensory register, short term memory and long term memory.
  • The MSM believes that information flows through the stores in a fixed linear order + each store has a different role in the memory process
• Sensory register

  • CODING: ALL SENSES. Gathers information from your sense organs. Each sense is coded differently
  • DURATION: LIMITED. Has a limited duration of 0.5-2 seconds.
  • CAPACITY: VERY LARGE. Has a very large capacity. Attention to information leads to transferal to STM, otherwise we forget it due to rapid decay.
• Short term memory

  • CODING: ACOUSTIC. Mainly acoustic (sounds). Similar sounds can lead to confusion. 
  • DURATION: LIMITED. Limited duration of 18-30 seconds.
  • CAPACITY: LIMITED: capacity of 5-9 items (Miller’s 7+/-2). Rehearsal (constant note repeating) allows retaining information in the STM. Doing this multiple times transfers memories from the STM to the LTM. Forgetting can occur due to displacement or decay.
• USING CHUNKING TO INCREASE STM CAPACITY: 

  • Capacity of STM is 5-9 items but can be increased by “chunking” information together in order to store more information in the short term memory. 
  • This is done by reducing the number of separate items overall and instead grouping them together.
• Long term memory

  • CODING: SEMANTICALLY. Codes information “semantically” (with meaning).
  • DURATION: FEW MINUTES TO A LIFETIME.
  • CAPACITY: UNLIMITED. Forgetting occurs through interference (proactive and retroactive) and retrieval failure (cue-dependent forgetting).
• +Strength of MSM: supporting research for capacity of STM

  • Jacobs used a digit span task where ppts were presented with a sequence of digits (e.g. four digits) + had to recall them in correct order. If correct, given a sequence of digits that was one number longer (i.e. five digits)- continued till ppts unable to correctly recall digits in right order - ppts digit span.
  • Mean digit span for letters - 7.3 items. Numbers - 9.3 items.
  • SB: Jacob’s findings regarding the digit span being 7.3 and 9.3 is inline with capacity range that MSM argues, which is 5-9.
  • Increases the validity of the MSM.
• +Strength of MSM: supporting research for the duration of the LTM

  • Bahrick tested ppts on ability to remember students from their high school year group. In one test, ppts were given 50 photos of some people who were in their highschool year group and others that were not. The participants were required to identify the ones that were in their year group. 
  • Participants tested within 15 years after graduation - 90% recognition accuracy. 48 years after graduation, recognition accuracy -70%.
• +PT2

  • SB: agrees with how memory can last for up to a lifetime as ppts that were tested even after 48 years had a high recognition rate.
  • This increases the validity of the MSM.
• -Weakness of MSM: LTM is not unitary as MSM proposes

  • Clive Wearing contracted a viral infection causing extensive brain damage- made him lose his long-term declarative memory. E.g: he has no memory of his wedding but still has use of his long-term procedural memory, e.g, still able to play the piano. 
  • WB: shows that there are different stores within the LTM, and therefore is not unitary like the MSM argues. 
  • This decreases the validity of the MSM. 
• +Strength of MSM: supporting research for coding in STM and LTM

  • Baddeley - gave ppts list of acoustically similar or different words or semantically similar/ different words. 
  • Found: immediate recall (using STM)- acoustically similar condition recalled fewer words in correct order.
  • Delayed recall (using LTM) - semantically similar condition had worse recall
  • SB: supports MSM - STM codes info acoustically + confusion for similar sounding words. LTM codes info semantically + confusion for words with similar meaning
  • Increases validity 
• Additional content

  When using our STM, acoustically similar words will create confusion (e.g flip, flit, flop, flap, flab.) 

  When using our LTM, semantically similar words will create confusion (e.g huge, large, great, giant.)
• Additional content

  Primary and recency effect:

  When learning and immediately recalling a sequence of items:

  • Recall of words at the start of the list (primary effect) and end of the list (recency effect) is much higher than the words from the middle of the list.
  • Words at the start are rehearsed so are transferred to the LTM.
  • Words at the end are still within the capacity of the STM.
  • Words in the middle are displaced from the STM by words at the end.
  • This shows how the STM and LTM are separate memory stores as the info at the start and the end of the list went to different stores.