STM vs. LTM

STM vs. LTM

1. STM: short term memory; LTM: long term memory

   • STM
     • Duration: Short
       • Peterson & Peterson
         • AO1
           • Aim: to test the duration that a STM can last
             • Nonsense consonant syllable
               • Count backwards from a 3 digit number (distraction)
                 • After 3-18 seconds, asked to recall the trigram
                   • Results: as the time of distraction increases the ability to recall decreases
         • AO2
           • Reliable: controlled environment therefore reproducible and can be checked for consistency
             • Demand characteristics: people told the method therefore decreases validity
     • Capacity: 7 +/- 2
       • A01
         • Miller
           • People coped reasonably well with counting 7 dots flashed onto a screen but not many more
             • 7 +/- 2 chunks, no matter what size but easier to remember smaller chunks (e.g. 1 syllable words) than longer chunks (e.g. 8 word phrases)
               • Chunking
         • Jacobs
           • Aim: to assess the capacity of STM (with both numbers and letters)
             • Strip of paper with a list of numbers/letters; "look, cover, say" technique
               • 9.3 numbers average; 7.3 letters average
                 • Easier to remember numbers than letters; maybe because only 9 numbers compared to 26 letters
         • May not be limited to chunks suggested (Cowan)
           • Vogel et al: looked at capacity for visual information and found a limit of 4 items
             • Culture bias: only done in Western culture, therefore difficult to generalise to other cultures
       • AO2
         • May be more limited (to 4 chunks
           • Cowan (2001) reviewed a variety of studies
             • Therefore Miller's study may not be as valid as first thought
         • Vogel et al. (2001)
           • Looked at capacity for visual information and found limited to 4 items
         • Culture bias
           • Only conducted in Western culture
             • Could be differences
               • Therefore difficult to generalise

2. Encoding

   • Baddeley
     • AO1
       • 4 conditions: acoustically similar and dissimilar; semantically similar and dissimilar
         • IV: ^; DV: number of errors; lists were of similar frequency in the English language
           • Participants asked to recall either immediately (STM) or delayed (LTM)
             • Immediate recall: more errors in acoustically similar lists; no difference in semantically similar/dissimilar
             • Delayed recall: opposite ^
             • Shows encoding for STM and LTM are different: STM = acoustic and LTM = semantic
     • AO2
       • Controlled so can be replicated to check consistency of results (reliable)
       • Can use and relate to other studies
       • Individual differences
         • Some people may be able to relate to words more than others
       • Order effects
         • Repetition could cause participants to get bored