MSM (Atkinson+Shiffrin 1968)

• a  structural, linear model of memory which focuses on how the different parts of the memory store information, and how information flows from one section to another.
• The Atkinson-Shiffrin model has three main stores - sensory register, short term memory and long term memory
• Sensory register


  • All stimuli from environment, e.g. sound of someone talking, passes into sensory register
  • coding is modality-specific so depends on the sense (2 main stores: iconic- visually coded info + echoic- acoustically coded info)
  • 1/2 sec duration
  • very high capacity
• Transfer from SR to STM


  From SR info either decays or if paid close attention to, passes into STM.
• STM


  • acoustically coded (sound)
  • limited capacity of 7+/- 2 items
  • duration of 18-30 sec
• Transfer from STM to LTM


  info is either displaced or maintenance rehearsed- material repeated to keep in STM and if rehearsed long enough it is transferred to LTM
• LTM


  • semantically coded (meaning)
  • potential unlimited capacity
  • potential duration of lifetime
• Retrieval from LTM

  info can decay in LTM or can be transferred back to STM by process called retrieval.
• strength/CA- supporting evidence (HM)


  • HM had his hippocampus removed to relieve his epilepsy symptoms
  • after surgery he experienced anterograde amnesia in which his STM remained intact but he could no longer form new LTM e.g he could briefly hold a number in his mind but couldnt retain it over the long term
  • supports view that STM +LTM are separate stores
  • But case study is based on 1 individual with brain condition so hard to generalise to wider audience as HM may have unique unknown brain changes before his surgery
  • not good support
• strength/CA- support from Baddely 1966


  • Baddeley (1966) conducted research into coding + found that STM acoustically coded whilst LTM semantically coded
  • supports concept of MSM as suggests STM +LTM separate stores
  • however, his research used artificial tasks such as recalling word lists which doesnt reflect the complexity of everyday memory tasks
  • people also use semantic coding for meaningful info even in STM
  • findings may be invalid
• limitation- argues that STM has substores (KF)


  • KF had a motorcycle accident and as a result suffered from amnesia
  • post-accident he could still recall visually presented info like written numbers but struggled with verbally presented info like spoken numbers
  • suggests STM isnt a single, unified store as the MSM proposed but instead is made up of different subcategories that separately process visual and auditory info
  • research contradicts MSM + suggest its oversimplified
• limitation- argues that MR isnt only type of rehearsal (craik+watkins)


  • Craik + watkins suggested 2 types of rehearsal
  • MR maintains info in STM whilst elaborative rehearsal moves the info into the LTM + invloved deeper processing and making meaningful connections
  • MSM doesnt account for different types of rehearsal so oversimplifies how info is encoded into LTM
  • unreliable as doesnt explain how info processed meaningfully tends to be better remembered than info that is just repeated