LTM and STM

• explicit memory - knowing that
• implicit memory - knowing how
• episodic memory - memory of event with emotions or context, explicit, time stamped, available for conscious inspection, less resistant to amnesia
• semantic memory - knowledge of the world, social customs or function of objects. available for conscious inspection, less resistant to amnesia
• procedural memory - how to do things, muscle based memory. unavailable for conscious inspection, implicit, more resistant to amnesia
• study into the duration of stm

  peterson and peterson

  • 24 students tested over 8 trials each shown a trigram and asked to recall the letters after counting back in threes from the 3 digit number for 3-18 seconds
  • 90% of pps were correct after 3 seconds
  • 20% correct after 9 seconds
  • 2% correct after 18 seconds
• study into coding of memory 


  baddely

  • 72 brittish pps split into 4 groups and asked to recall a word list in the correct order. 1 - acoustically similar words, 2 - acoustically dissimilar words, 3 - semantically similar words, 4 - semantically dissimilar words
  • when recalled immediately after they tended to do worse with acoustically similar words - stm is acoustic
  • when recalled after 20 minutes they did worse on the semantically dissimilar words - ltm is semantic
• study into the capacity of stm

  jacobs

  pps given 4 digits if remembered correctly the digits increased until pps remembers them incorrectly. the mean for digits was 9.3 items and for letters was 7.3 items

  miller

  people can recall 5 words as easily as 5 letters due to a method called 'chunking'
• study into duration of ltm

  bahrick

  • 392 americans were tested, ages between 17 and 74, on the memory of their classmates
  • they took a photo recognition test of 50 photos
  • those tested 15 years after leaving were 90% accurate declining to 30% of who left 48 years before
  • duration is possibly a lifetime
• short term memory


  duration - 18-30 seconds

  capacity - 7+-2

  coding - mainly acoustic
• long term memory

  duration - unlimited

  capacity - unlimited

  coding - mainly semantic