multi-store model of memory

• define coding

  the way in which info is changed so it can be stored in the memory.
• define capacity

  quantity of info that can be held in the memory
• define duration

  amount of time that info can be stored in the memory
• coding for STM

  acoustic
• coding for LTM

  semantic
• capacity for STM

  limited, 5 -9 items
• capacity for LTM

  unlimited
• duration for STM

  less than 30 seconds
• duration for LTM

  up to a lifetime
• outline research for CAPACITY of STM

  • Jacob's digit span

  1. researcher reads out 4 digits and PP recalls out loud in correct order
  2. If correct, researcher reads out 5 digits and PP recalls
  3. process carries on until PP can no longer recall order correctly
  4. This indicates participants digit span
• results of Jacob's digit span (CAPACITY OF STM)

  • digit mean span = 9.3 items
  • letter mean span = 7.3 items
• evaluate Jacob's digit span (CAPACITY OF STM)

  • it has been replicated by better controlled studies = suggests study is a valid test of STM capacity
• outline Miller's research (CAPACITY OF STM)

  • magic number 7: observed everyday practices and noticed things come in sevens = suggested STM span was 7 +/-2 items
  • chunking: noticed that people can recall 5 words as easily as 5 letters = suggests we group sets of digits/letters into chunks
• evaluate Miller's research (CAPACITY OF STM - magic no.7 and chunking)

  • Miller may have overestimated STM capacity = Cowan reviewed other research and found capacity is only out 4 +/-1 chunks
  • This suggests the lower end of Miller's estimate is more appropriate.
• outline research for DURATION of STM

  • conducted by Peterson and Peterson
  • 24 uni students
  • 8 trials each

  1. each trial, PP given trigram of letters and a 3 digit number to count backwards from until told to stop.
  2. different time intervals given in each trial: 3, 6, 9, 12, 15, 18 - to test duration.
  3. counting backwards = prevents mental rehearsal of trigram
• results of research on DURATION of STM

  • After 3 seconds = average recall was 80 %
  • After 18 seconds = average recall was 3 %
  • This suggests STM duration is around 18 seconds unless info is rehearsed
• evaluate research on DURATION of STM (LIMITATIONS)

  • artificial stimulus = doesn't reflect everyday memory where things we try to remember have meaning = lacked external validity.
  • HOWEVER, study not completely irrelevant bc we sometimes try to remember meaningless material (e.g. phone numbers)
  • 24 participants = small sample size = anomalies or individual differences can affect results.
• evaluate research on DURATION of STM (STRENGTHS)

  trigram = easy to replicate = checks validity of experiment.
• outline research for DURATION of LTM

  • conducted by Bahrick et al.
  • 392 american participants between 17 - 74 yrs
  • high school yearbook recall:

  1. photo recognition = test of 50 photos from PPs yearbooks
  2. free recall = PPs recalled all the names of their graduating class
• results of research for DURATION of LTM - tested within 15 yrs of graduation

  • photo recognition = 90 %
  • free recall = 60 %
• results for research for DURATION of LTM - tested after 48 yrs of graduation

  • photo recognition = 70 %
  • free recall = 30 %
• conclusion for research for DURATION of LTM

  • recall can be accurate over a long period of time
  • LTM can last up to a lifetime
• evaluate research for DURATION of LTM

  • high external validity because meaningful memories = findings reflect a more realistic estimate of duration of LTM
• outline research on CODING of STM + LTM

  • conducted by Baddeley
  • different lists of words given to 4 groups of PPs to remember
  • STM = recall immediately
  • LTM = recall after 20 mins

  1. acoustically similar
  2. acoustically different
  3. semantically similar
  4. semantically different
• results of research on CODING of STM + LTM

  • STM did worse with acoustically similar words
  • LTM did worse with semantically similar words
  • Because they were coded in the same way
  • Concluded that STM codes acoustically and LTM codes semantically.
• evaluate research on CODING of STM + LTM (STRENGTHS)

  • identified clear differences between memory stores
  • easy to replicate = can check validity
• evaluate research on CODING of STM + LTM (LIMITATION)

  • artificial stimuli = lacked realism
  • words had no meaning to participants so doesn't reflect real life situations where people would use semantic coding with STM to code more meaningful info.
  • Also doesn't tell us about coding with different memory tasks
• Outline the Multistore Model of Memory

  • By Atkinson and Shiffrin
  • Describes the flow of info through the memory processes and how info is transferred from one store to another.

  1. info from environmental stimuli enters by the sensory register
  2. attention payed to info = enters the STM
  3. STM is a temporary store = prolonged rehearsal transfers it to the LTM
  4. maintenance rehearsal keeps it in the STM so response (remembering) can occur
  5. to recall info from LTM to STM = retrieval
  6. no maintenance rehearsal = forget info
• outline the Sensory Register - MSM

  • memory store for each sense = all info from environment passes into the sensory register
  • CAPACITY: huge, how much is coming into senses
  • DURATION: milliseconds, most wont even register in consciousness
  • CODING:

  1. echoic = acoustic
  2. iconic = visual
  3. haptic = touch
  4. gustatory = taste
  5. olfactory = smell
• evaluate MSM (strengths)

  • research supporting MSM theory that "STM and LTM are two different stores"
  • difference in coding = Baddeley
  • difference in capacity = Peterson and Barrack et al.
  • difference in duration = Jacobs
• evaluate MSM (LIMITATIONS)

  • counterpoint to strength = experiment material is meaningless = lacks external validity
  • evidence of more than one STM store = KF case study by Shallice and Warrington
  • prolonged rehearsal is not needed to transfer info to LTM. MSM states that more rehearsal = more likely to enter LTM. But Craik and Watson found that the type of rehearsal is more important = elaborative rehearsal is linking info to your existing knowledge. This suggests MSM doesn't fully explain how long term storage is achieved.