Memory- coding, capacity and duration

Memory- coding, capacity and duration

1. Coding

   • The format in which information is stored
     • Acoustic
       • STM
     • Semantic
       • LTM
   • Baddeley, 1966
     • Gave 4 groups 4 different lists of words
       • Group1
         • Acoustically similar words
           • Cat, mat, bat
       • Group 2
         • Acoustically dissimilar words
           • dog, food, man
       • Group 3
         • Semantically similar
           • huge, large, big
       • Group 4
         • Semantically dissimilar
           • few, eat, carpet
     • Findings
       • Immediate recall (STM)
         • Struggled with acoustically similar
       • 20 minutes later (LTM)
         • Struggled with semantically similar
     • Evaluation
       • Artificial stimuli
         • Word lists have no personal meaning to participants
           • Difficult to generalise

2. Duration

   • The length of time information can be stored
     • 18-30 seconds
       • STM
     • Permanent
       • LTM
     • Peterson and Peterson, 1959
       • STM
       • Participants given a consonant syllable (e.g. YCG) and a three digit number (e.g. 547)
         • Counted back from number until told to stop
           • Had to recall consonant syllable
           • Retention interval of 3,6,9,12,15 or 18 seconds
             • Recall worse at 18 seconds
       • Evaluation
         • Meaningless stimuli
           • Difficult to generalise
           • Lack of external validity
     • Bahrick, 1975
       • LTM
       • Showed 17-74 year old people their yearbooks
         • 15 years after graduation
           • 90% accuracy
         • 48 years after graduation
           • 70% accuracy
       • Asked 17-74 year old people to freely recall students in their graduating class
         • 15 years after graduation
           • 60% accuracy
         • 48 years after graduation
           • 30% accuracy
       • Evaluation
         • High external validity
           • Meaningful stimuli

3. Capacity

   • The amount of information that can be stored
     • 5-9 items
       • STM
     • Unlimited
       • LTM
   • Jacobs, 1887
     • Digit span
       • Recall of digits, increasing each time
         • Average was 9.3 digits
     • Evaluation
       • Lacking validity
         • Lack of control over confounding variables due to era
   • Miller, 1956
     • Chunking
       • People can recall five words just as well as five letters
         • Grouping letters or digits into chunks
     • Evaluation
       • Contradictory evidence
         • Four chunks more likely