coding capacity & duration of memory

research on coding
1. stored in different formats
  1. converting info from one format to another = coding
2. Baddeley
  1. different lists of words for people to remember
    1. acoustically similar
      1. cat
      2. cab
      3. can
    2. acoustically different
      1. pit
      2. few
    3. semantically similar
      1. great
      2. big
      3. large
    4. semantically different
      1. good
      2. huge
      3. hot
  2. shown the words had to say them in the right order
    1. immediately after = stm
      1. worse with acoustically similar
    2. after 20 minutes = ltm
      1. worse in semantically similar
research on capacity
1. digit span
  1. how much can stm hold
    1. Jacobs
      1. 4 digits recall in order
        if correct move to 5 digits etc..
        mean = 9.3 items
        mean for letters = 7.3
2. span of memory & chunking
  1. Miller
    1. things come in sevens
      1. 7 notes in a scale
      2. 7 days in a week
      3. 7 deadly sins
    2. span of stm = 7 + - 2
    3. people can remember 5 words as well as letters
      1. they do this by chunking
        grouping digits or letters together
research on duration
1. duration of stm
  1. Peterson
    1. 24 undergraduate students
      1. 8 trials
        each trial = consonant syllable e.g. YCG and a 3 digit number to remember
        then count backwards from that number until told to stop
        prevent mental rehearsal of letters
        told to stop after 3 6 9 12 15 or 18 seconds (retention interval)
    2. results
      1. stm very short duration unless rehearsed
2. duration of ltm
  1. Bahrick
    1. 392 American participants 17 - 74
      1. 2 conditions
        photo recognition - 50 photos from yearbook
        free recall - name as many people as they could remember
    2. results
      1. under 15 years of graduation
        90% accurate photo recognition
        60% free recall
      2. after 48 years
        70% photo recognition
        30% free recall
      3. ltm lasts for a long time
evaluation - coding
1. artificial stimuli
  1. word list - no personal meaning
    1. can we really generalise it
evaluation - capacity
1. lacking validity
  1. long time ago
    1. not much control of variables
      1. participants may have been distracted
      2. however there has been research to support it
2. not so many chunks
  1. Miller overestimated the capacity of stm
    1. Cowan reviewed other research
      1. found capacity about 4 chunks
evaluation - duration
1. meaningless stimuli - Peterson
  1. stimulus artificial
    1. doesn't reflect real life
      1. lacked external validity
        however some things like phone numbers may be meaningless
2. higher external validity - Bahrick
  1. real life meaningful memories
    1. confounding variables...
      1. the people had probably checked their yearbook since graduation
evaluation +
1. criticising Peterson
  1. one reason why we forget things in stm is memory trace
    1. it disappears if not rehearsed
      1. Peterson = participants counted down - displaced other info
  2. or the info is displaced
    1. limited capacity and new info will push old out

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coding capacity & duration of memory

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	Created by Daisy U about 8 years ago