STM, LTM & Duration

STM, LTM & Duration

1. Duration of LTM

   • Lasts from 2-100+ hours
   • Shepard (1967
     • Tested the duration of LTM
     • Showed participants 612 memorable pictures, one at a time
     • Hour later shown some of the pictures with others.
       • Perfect recognition
     • Four months later
       • 50% accurate recognition
   • Bahrick et al (1975)
     • 48 years on, 70% accuracy
     • Put names to faces from high school yearbook
     • material that was remembered was more meaningful to participants
       • Duration of long-term memories was better

2. Evaluation

   • Marsh et al
     • When P's not expecting being tested, only lasts 2s.
   • Nairne et al
     • Found items could be recalled after 96s
     • They used the same item for recall each time
     • They don't have the interference between items to decrease recall.
     • Info remains in STM unless replaced or overwritten
   • P+P - Validity
     • Internal
       • Only studying one type of memory
         • For syllables and words
       • When counting backwards, items could have been displaced.

3. Duration of STM

   • Limited capacity
   • Lasts for a very short time, unless rehearsed
   • Memory for immediate events
   • Peterson and Peterson (1959)
     • Experimenter said consonant syllable then a 3 digit number
       • Consonant syllable has no meaning
     • After hearing syllable and number, p's count back from number in 3s or 4s until told to stop
       • Counting back was to prevent maintenance rehearsal
     • Then asked to recall
     • 2 practice and 8 real trials
       • Each trial, retention time is different
     • 90% accuracy when 3s interval, 2% with 18s interval
     • Suggests that when rehearsal is prevented, STM lasts around 20s