coding, capacity and duration

coding, capacity and duration

1. Research on coding

   • Alan Baddeley 1966
     • 4 different lists to 4 groups:
       • acustically similar
         • had the worst results if the task was done immediately afterwards (STM)
       • acoustically dissimilar
       • semantically similar
         • had the worst results after a 20 min interval (LTM)
       • semantically dissimilar
     • Evaluation
       • artificial stimuli used not meaningful information used
         • the word lists had no personal meaning to the pp's, therefore there was no urge to know them

2. Research on capacity

   • Digit span
     • Jacobs 1887
     • average 7.3 for letters
     • average 9.3 for items
     • one limitation is that it was conducted a long time ago
   • span of memory and chunking
     • Miller 1956
       • things come in 7's; days of the week, deadly sins ect...
         • therefore digit span 7 + or - 2
       • people recall 5 words as well as 5 letters
         • this is called chunking
       • Miller may have overestimated the capacity of STM
         • Cowan: "Capacity of STM is only about 4 chunks"

3. Research on duration

   • STM
     • Peterson and Peterson 1959
       • recall trigrams after various intervals whilst counting backwards in threes of fours from a random number
       • the longer the interval the less of the trigrams remembered
       • STM has a limited duration when rehearsal is prevented
       • however they used artificial stimuli
   • LTM
     • Bahrick et al 1975
       • year book photo recognition tested in different ways
         • 50 photos, some from the pp's yearbook
         • free recall, pp's called out names of their graduating class
       • confounding variables not controlled, pp's could have looked back at their yearbook photos, yearly rehearsing them