Memory - coding, capacity and duration of memory

• What is coding? format in which info is stored in various memory stores
• what did Alan Baddeley do? gave different list of words to form groups to remember
• When did Baddeley conduct his coding study?


  1966a, 1966b
• What was group 1?

  acoustically similar
• What was group 2?

  acoustically dissimilar
• what was group 3?


  semantically similar
• what was group 4?


  semantically dissimilar
• what was alan baddeleys findings? when they recalled words from STM, they did worse with acoustically similar words

  after 20 mins, using the LTM they did worse with semantically similar words
• overall, what does baddeleys research on coding suggest? info is coded acoustically in STM and semantically in LTM
• what are the strengths of baddeleys study? Point: P - showed a clear difference between the two stores
• what are the strengths of baddeleys study? Evidence: E - later research shows theres exceptions but the idea that STM is acoustic and LTM is semantic has stood the test of time
• what are the strengths of baddeleys study? Therefore...: T - it is a vital step in understanding the memory system and led to the multi store model of memory
• what are the weaknesses of baddeleys study? Point: P - used artificial stimuli, not meaningful material
• what are the weaknesses of baddeleys study? Evidence: E - the words had no personal meaning so doesnt tell us about coding in everyday life, may use semantic coding for STM when processing meaningful info
• what are the weaknesses of baddeleys study? Therefore...: T - his findings have limited application
• what is capacity? amount of info that can be held in the memory store
• who conducted research on capacity? Jacobs (1887) and Miller (1956)
• how did jacobs find out STM's capacity? measured digit span - e.g researcher reads out 4 digits and participants recall in order and if correct they read out 5 digits and so on until they can't recall in order correctly
• what were jacobs findings? -Mean digit span was 9.3

  -Mean letter span was 7.3
• what did george miller do? made observations of everyday practice` e.g he noted that everything came in 7s, 7 days of the week, 7 deadly sins etc
• what were millers findings? the span of STM is 7 plus or minus 2

  people can recall 5 words as easy as 5 letters by chunking
• what is chunking? grouping sets of digits or letters into units and chunks
• what are the strengths of Jacob's study? P - has been replicated so is a valid study

  E - old study, early research lacked controls e.g digit spans underestimated as they were distracted however his findings have been confirmed by controlled studies (Bopp and Verhaegen 2005)

  T - his study is a valid test of digit span in LTM
• what are the weaknesses of Millers study? P - may have overestimated STM capacity

  E - Nelson Cowan 2001 reviewed other research and found STM capacity is 4 plus or minus 1

  T - the lower end of millers research (5 items) is more appropriate than 7 items
• what is duration? the length of time something can be held in memory for
• who studied the duration of STM? Peterson and Peterson (1959)
• what did peterson and peterson do? tested 24 students in 8 trials

  on each trial, a student was given a consonant syllable to remember and a 3 digit number

  student counted backwards from this number to prevent mental rehearsal of consonant syllable

  they were asked to stop after 3,6,912,15,18 seconds
• what were his findings? after 3 seconds - recall is 80%

  after 18 seconds- recall is 3%
• what were the conclusions of peterson and petersons study? STM duration is 18 seconds
• who studied the duration of LTM? Bahrick et al (1975)
• What did Bahrick do? Asked 392 high school graduates between the age 17 and 74 to recall people via their year books.

  He asked in two different ways

  1) photo recognition of 50 photos

  2) Free recall of any name.
• what was Bahricks findings? pps could remember former classmates with 90% accuracy 15 years after grad.

  decreased to 70% after 48 years

  free recall was less accurate than recognition - 60% after 15 years, 30% after 48 years
• what was Bahricks conclusions? LTM may last up to a lifetime for some material
• what are the strengths of Bahricks research? P - high external validity

  E - researchers investigated meaningful memories, when studies on LTM were conducted with meaningless pics, recall rates were lower (shepard 1967)

  T - his findings reflect a more real estimate of the duration of LTM
• what are the weaknesses of Peterson and petersons research? P - stimulus material = artificial

  E - the study isnt completely irrelevant as we do remember meaningless info BUT recalling consonant syllables doesnt reflect everyday memory activities where what we are trying to remember = meaningful