CODING , CAPACITY + MEMORY DURATION

• Does Long-term Memory (LTM) have limited or unlimited storage capacity?

  Unlimited
• DIGIT SPAN

  • Studied by Jacobs (1887) to test capacity
  • Researcher reads 4 digits + participants recalls them in same order (repeats until p gets it incorrect)
  • The mean digit span = 9.3
  • The mean letter span = 7.3
• George Miller (1965) found that the capacity of STM = 7 +/- 2 items (between 5 and 9)
• What is the term for grouping sets of digits/letters into units or chunks?

  Chunking
• PETERSON + PETERSON (1959)

  • 24 students took part in 8 trials each
  • Given consonant syllable (HBD) to remember
  • Then given 3 digit number to remember to count back in 3 seconds until stopped (this stops process of rehearsal)
  • Retention Interval (3 , 6 , 9 , 12 , 15 or 18 secs)

  RESULTS

  • After 3 seconds, recall = 80%
  • After 18 seconds = 10%
• P + P's (1959) study suggests STM duration ≈ between 18 + 30 seconds (unless rehearsal)
• DURATION OF LTM (Bahrick - 1975) - PROCEDURE

  • Studied 392 Americans (age 17 - 74)
  • Got their highschool yearbook
  • Recall tested in :

  1. Photo recognition of 50 photos
  2. Free recall of graduating class
• DURATION OF LTM (Bahrick - 1975) - FINDINGS

  • P's tested within 15 years of graduation = 90% accurate (photo recognition)
  • After 48 years = 70% accurate (photo recognition)
  • After 15 years (free recall) = 60%
  • After 48 years = 30%
• Were people less accurate in photo recognition or free recall?

  Free recall
• Coding is the format information is stored in memory stores
• Coding can be presented either acoustically or semnatically
• Is acoustic to do with sound or meaning?

  Sound
• Is semantic to do with sound or meaning?

  Meaning
• BADDELEY (1966) - CODING PROCEDURE

  • Gave different word lists to 4 groups to remember:

  1. Acoustically similar eg can , cab
  2. Acoustically dissimilar eg dog , bin
  3. Semantically similar eg large , big
  4. Semantically dissimilar eg good , ugly
• BADDELEY (1966) - CODING FINDINGS

  • Recalling from STM = did worse with acoustically similar words
  • Recalling from LTM (20 mins) = did worse with semantically similar words
  • Suggests info coded acoustically in STM + semantically in LTM