msm

• serial position effect

  primacy and recency effect where you can only remember first and last numbers in a sequence
• primacy effect

  can remember the first numbers in a sequence due to them being stored in LTM
• recency effect

  can remember the last numbers in a sequence as they are still in the STM
• sensory memory

  • receives info from the environment (via senses)
  • large capacity
  • brief duration (less than 1 sec)
  • encoding - specific (e.g. visual for iconic memory, auditory fire choices memory, etc)
  • attention is needed to transfer memory into STM
• STM

  • capacity - 7+/ - 2 items (Miller 1956)
  • duration - 18-30 seconds (Peterson & Peterson)
  • encoding - primarily acoustic
  • rehearsal moves info into LTM otherwise it decays or is displaced
• LTM

  • capacity - unlimited
  • duration - potentially life long
  • encoding - semantic
  • retrieval brings info back to STM for use
• brain scans supporting MSM

  • fMRI scans show how the prefrontal cortex is active during STM tasks and the hippocampus is active during LTM
  • proves that there are different memory stores
• criticisms of MSM

  • oversimplifies memory - KF case study shows that only his verbal STM was damaged and that his visual was still intact proves there is more than 1 store
  • overemphasis on rehearsal - craik & lockhart suggests levels of processing (deep processing) is more important than rehearsal for LTM storage & that some memories can form without rehearsal
  • ignores different types of LTM - Tulving’s showed that there is procedural, semantic and episodic memory
• peterson & peterson aim

  to see how long info lasts in STM without rehearsal
• peterson & peterson procedure

  • 24 students given trigrams like XAF to remember
  • to prevent rehearsal they counted backwards in 3s
  • recall was tested after 3, 6, 9, 12, 15 or 18 seconds
• peterson & peterson findings

  • 80% recall at 3 seconds but only 10% at 18 seconds
  • STM duration is very short without rehearsal
• strengths of peterson & peterson

  • controlled lab experiment - high internal validity as variables were tightly controlled
  • practical applications - helps understand memory limitations
• weaknesses of peterson & peterson

  • low ecological validity - trigrams are artificial so may not reflect real world memory use
  • interference from counting - the task may have displaced memory rather than measuring STM duration
  • sample bias - only used psychology students so may nit generalise to other populations