the multi store model

• encoding


  how sensory input is represented by the memory system / the format
• capacity


  how much information can be stored
• duration


  how long the information can be held in storage
• model

  a simplified version of reality, often in form of a diagram
• memory


  a recollection and storage of events, learning and feelings that have occured for future use
• sperling (1960) sensory memory test


  • showed a chart containing letters for 50 milliseconds
  • asked participants to recall as many letters possible
  • most recalled 4-5 but said they were aware of more
  • this supports the MSM proposing information decays quickly from sensory memory
• conclusions made from sperlings findings


  • items remain in SM for a brief period of time, less than 2s
  • 3 different stores: iconic (visual), echoic (hear), haptic (touch)
  • cant control what enters our SM but can actively select certain items to transmit to
• labatory experiment - strengths and weaknesses

  + same conditions for everyone

  + allows repetition

  + large sample size

  -ethics - could be stressful

  -very artificial environment and test materials
• digit span test- joseph jacobs (1887)


  participants are read strings of numbers that get longer and longer, and have to write them down in the correct order
• 🙂 and 🙁 of joseph jacobs

  🙁 some think that capacity is less - it is 4 (+/-1)

  🙂 other studies have confirmed his results, supporting the validity of his study
• miller (1956)


  • proposed we can half 5-7 items in our STM (7+/- 2)
  • magic number 7
  • belived 'chunk' was the basic unit of STM
  • memory span is determined by 'chunks' of information rather than number of letters/numbers
• maintenance rehearsal 


  continually repeating the information - potentially this can lead to transfer
• elaborative rehearsal


  the information has to be made meaningful eg. when meeting someone new and linking their name to a place or something they said to remember their name
• peterson and peterson (1959)


  • how long items would remain in STM when rehearsal is prevented (18-30s)
  • Ps were briefly shown a consonant trigram (CPW,NGV)
  • they were then asked to count backwards in 3s
  • after 3,6,9,12,15 or 18 seconds Ps were asked to recall the original trigram
  • fewer trigrams were recalled as the time intervals lengthened
  • if rehearsal is prevented, info decays rapidly from STM
• bahrick (1975)


  • establishing existence of VLTM
  • seeing if there is a difference between recognition and recall
  • used graduates from a highschool in america across 50 yrs
  • 392 students ages 17-74
  • group 1 - given names and photo
  • group 2 - just given photo
  • VLTM is better measured by recognition, people can remember certain types of info for almost a lifetime
  • A02 eval - used meaningful stimulus material (yearbook) and tested people for memories from their own lives
  • it is unclear whether drop off in accuracy after 47 yrs reflects limits of duration or more general decline in memory with age
• acoustic encoding


  with sounds, main way of encoding in STM
• semantic encoding


  the meaning of the stimulus
• acoustic encoding in STM (conrad 1964)


  • when having to remember something for a short time (eg. phone number) you repeat it acoustically
  • suggests STM encodes info acoustically
  • investigated this by comparing performance with acoustically similar (B,G,C,T) and dissimilar (F,J,X,M) visually presented data
  • 6 letters at a time, displayed for 0.75 of a second
  • Ps had to recall letters in the order they were presented
  • when letters sounded like errors were made in terms of sound confusions (eg. S instead of X)
  • we must convert visually presented material to acoustic encoding in STM
• semantic encoding in LTM (baddeley 1966)


  • aim to explore the effects of acoustic and semantic encoding in LTM and STM
  • in LTM study a list of 10 words was presented and recall was tested after interval of 20 minutes
  • when Ps were recalling from LTM recall was better for words that didnt have the same meaning (semantically dissimilar words)
  • concluded that STM relies heavily on acoustic encoding
  • LTM primarily makes use of semantic encoding
• sensory memory


  • capacity - large
  • duration - less than 2 seconds
  • encoding - acoustic / semantic (iconic, echoic, haptic)
  • forgetting - very quickly
• short term memory


  • capacity - 7 (+/- 2 ) items
  • duration - 18-30 seconds when rehearsal is prevented
  • encoding - acoustic
  • forgetting - quickly unless types of rehearsal are used
• long term memory


  • capacity - no known limit
  • duration - almost a lifetime
  • encoding - semantic
  • forgetting - remembered for a long time
• the multi store model

  
• the primacy - recency effect : glanzer and cunitz (1966)


  Ps were given a long list of words and were asked to recall as many possible. the researcher would then plot on a graph where the word appeared on the list. it was found free recall produces a serial curve:

  • recency effect - words presented at the end of the list were recalled best because they are still in STM
  • primacy effect - words at the beginning of the lidt have been rehearsed and are in LTM
  • asymptote - words in the middle are poorly recalled as they have been displaced by later words in the list - not rehearsed sufficently
• primacy / recency effect A03 evaluation 


  support -

  shows long term and short term memories and 2 distinct stores, as the words at the end of the list are in the STM, shown by the recency effect and the words at the beginning of the list are in the LTM, shown by the primacy effect.

  issues -

  methodological issue - lab experiment, artifical, not representitive of everyday life
• the case of HM


  • underwent brain surgery that removed the hippocampus from both sides of his brain
  • he couldnt form new LTMs (would repeatedly read same magazine) or recall what he had eaten earlier the same day but performed well on the digit span test, a measure of STM
  • supports MSM by showing the memories have 2 separate stores
• the case of KF


  • suffered brain damage that effected his STM, but his LTM functioned normally still
  • has a capacity of 1-2 items, only able to recall the last bit of information he had in his STM
  • his verbal STM was damaged despite his visual memory still being intact - had limited digit span when numbers were read out loud to him, but recalled better when he was able to read them himself
  • issue - suggests STM isnt a unitary store and has different parts dedicated to processing different types of information
• brain scanning techniques


  • PET and MRI scans provide evidence for existance of 2 separate stores. squires (1992) found...
  • hippocampus is active during LTM tasks
  • areas in pre-frontal cortex are active during STM tasks
  • further evidence of 2 separate stores
• ecological validity


  • in everyday life memories are related to faces, names, facts, places
  • in studies digits, letters and meaningless consonant trigrams are used
  • limited in explanatory power as it relies on research materials that lack relevance to everyday life
  • ecological validity is restricted