coding capacity and duration

• coding: the format in which information is stored in the various memory stores
• baddeley gave different lists of words to 4 groups of pps to remember:

  • group 1 (acoustically similar) e.g cat, cab, can
  • group 2 (acoustically dissimilar) e.g pit, few, cow
  • group 3 (semantically similar) e.g great, large, big
  • group 4 (semantically dissimilar) e.g good, huge, hot
• results:

  pps were shown the words and asked to recall in order

  • they did this task immediately, using STM, they did worse with acoustically similar words
  • when they recalled the word list after 20 mins, using LTM, they did worse with semantically similar words
  • these findings suggest info is coded acoustically in STM and semantically in LTM
• P - one strength of baddeley's study is that it identified a clear difference between two memory stores

  E - he found that STM uses mostly acoustic coding, while LTM mainly uses semantic

  E - later research found some exceptions but the basic concept that STM and LTM use different ways to store information has stayed true. this idea led to the multi-store model of memory, which is still important in psychology today.

  L - Baddeley's study was a crucial step in understanding memory, showing how information is stored and remembered differently in our minds.
• capacity: the amount of information that can be held in a memory store
• joseph jacobs found out how much info STM can hold at one time (capacity) by measuring digit span
• digit span:

  • the researcher reads out 4 digits and the particpant recalls these out loud in the correct order
  • if this is correct the researcher reads out 5 digits and so on until the participant cannot recall the order correctly. this indicates the individual's digit span.
  • jacobs found that the mean span for digits across all participants was 9.3 items. the mean span for letters was 7.3
• george miller made observations of everyday practice, noting that things come in sevens

  • miller thought the span (capacity) of STM is about 7 items plus or minus 2
• miller noted that people can recall 5 words as easily as they can recall 5 letters. we do this by chunking - grouping sets of digits or letters into units or chunks
• P - one strength of jacobs study is that it has been replicated

  E - although it's an old study and early psychology research wasn't always well controlled, jacobs work was held up overtime. some participant digit spans might have been underestimated because they were distracted during testing

  E - but newer studies with better controls have confirmed jacobs' findings. proving the validity of jacobs study despite the limitations of early research

  L - in summary, jacobs' study is important because other studies have confirmed his findings, showing that jacobs' work is still relevant today
• P - one limitation of miller's research is that he may have overestimated

  E - a study proposed that STM's capacity is around 4 plus or minus 1 chunks, contradicting Miller's claim of 7 items.

  E - This indicates that Miller's higher estimate may not accurately reflect the true limitations of STM, with the lower end of his range (five items) aligning more closely with current understanding.

  L - thus while miller's work was important in highlighting the limited capacity of STM, following research has refined our understanding suggesting that his estimate of 7 items may have been too generous.
• duration: the length of time information can be held in memory
• peterson and peterson

  • tested 24 students in 8 trials
  • student was given a consonant syllable (e.g YCG) to remember
  • they were also given a 3 digit number
  • the student counted backwards from this number until told to stop (to prevent mental rehearsal of consonant syllable) which would increase the duration of STM memory for the syllable
• peterson and peterson

  • on each trial they were told to stop after varying periods of time: 3,6,9,12,15 or 18 seconds (retention interval)
  • after 3 seconds, average recall was about 80%, after 18 seconds it was about 3%
  • findings suggested that STM duration may be about 18 seconds, unless we repeat the info over and over (verbal rehearsal)
• bahrick

  • studied 392 american participants aged between 17 and 74
  • high school yearbooks were obtained from the participants or directly from some schools
• bahrick: recall was tested in various ways

  • photo recognition test consisting of 50 photos
  • free recall test where participants recalled all the names of their graduating class
• findings of bahrick

  • participants tested within 15 years of graduation were about 90% accurate in photo recognition
  • after 48 years, recall declined to about 70% for photo recognition
  • free recall was less accurate than recognition - about 60% after 15 years, dropping to 30% after 48 years
  • this shows LTM may last up to a lifetime for some material
• P - A limitation of Peterson and Peterson's study lies in its use of artificial stimulus material.

  E - the study is not completely irrelevant because we do sometimes try to remember fairly meaningless material

  E - however the study's reliance on consonant syllables fails to capture the diverse array of memory tasks we encounter in daily life.

  L - Therefore, the study's findings may not fully apply to the broader spectrum of memory demands we face, highlighting a limitation in its external validity.
• P - one strength of bahrick et al's study is that it has high external validity

  E - compared to meaningless pictures to be remembered, meaningful memories of people's names and faces had higher recall rates

  E - therefore their study reflects what we actually try to remember in daily life better than studies with meaningless info

  L - this suggests that bahrick et al's findings reflect a more 'real' estimate of the duration of LTM