coding, capacity and duration of memory

• coding is...


  the format in which information is stored in various memory stores
• capacity is...


  the amount of memory that can be held in a memory store
• duration is...


  the length of time that information can be held in a memory store
• what is short-term memory?


  the limited-capacity memory store
• what is long-term memory?


  the permanent memory store
• who conducted research on coding?

  baddelely (1966a, 1966b)
• what was the procedure of baddeley's research?


  giving lists of different words to different groups of participants and asking them to recall the words
• what are some examples of these groups of words?

  • group 1 = acoustically similar (cat, car, cab)
  • group 2 = acoustically dissimilar (pit, few, cow)
  • group 3 = semantically similar (great, large, big)
  • group 4 = semantically dissimilar (hot, huge, good)
• how did participants perform when having to do the recall task immediently after hearing the words?


  they tended to do worse on acoustically similar words
• how did participants perform when having to do the task after a twenty minute interval?


  they tended to perform worse on semantically similar words
• what did baddeley's study demonstrate?


  suggests that information is stored semantically in long-term memory
• what is the capacity of short-term memory?


  5 to 9 items
• what is the duration of short-term memory?


  18 to 30 seconds
• what is the capacity of long-term memory?


  potentially unlimited
• what is the duration of long-term memory?


  unlimited
• what did miller's research argue?


  that because most things come in sevens (days of the week, colours of the rainbow, notes on a musical scale) we on average can recall that many items
• what is chunking?


  when we break down a longer list that we need to remember in order to make it easier
• who conducted the digit span test?

  jacobs, 1887
• what was the procedure of the digit span test?


  participant had to recall a list of digits in the correct order

  each time, another digit was added
• what was the mean digit span for numbers?


  9.3
• what was the mean digit span for letters?


  7.3
• who conducted research on the duration of short-term memory?

  peterson and peterson (1959)
• what occurred during peterson and peterson's study?


  24 students were given a random constonant syllable (example = YCG) and also given a 3 digit number

  participants had to count down backwards from the number that they were given, in order to prevent rehearsal

  participants were then asked to recall the 3 letters
• what was the results of peterson and peterson's study?


  that the duration of STM is about 18 seconds (unless rehearsed)
• who conducted research on the duration of long-term memory?

  bahrick et al (1975)
• what was the procedure of bahrick et al's study?


  392 americans

  asked to recall from their high school yearbook - photo recognition and free recall tests (either naming from looking at the photos, or just attempting to remember)
• what was the results of bahrick et al's study?


  after 15 years = 90% accuracy in photo recognition, 60% accuracy in free recall

  after 48 years = 70% accuracy in photo recognition, 30% accuracy in free recall

  demonstrates how LTM can potentially last a lifetime
• what are some evaluation points for coding?


  supporting research suggests that STM uses acoustic coding and LTM uses semantic coding

  artificial stimuli - Baddeley's word lists had no real meaning in everyday life

  limited application and difficult to apply to everyday life
• what are some evaluation points for capacity?


  the original digit span test has been replicated with similar results - even though it is very old

  miller may have over-estimated how many chunks people can recall on average - cowan (2001) found that 4 chunks (3-5) may be more likely to be recalled on average than 7
• what are some evaluation points for duration?


  bahrick et al - used meaningful memories (real life yearbook) and so this study has high external validity, a "real" estimate of the duration of LTM

  peterson and peterson - used meaningless stimuli, doesn't reflect that of everyday life and so lacks external validity