Memory

Memory

1. Coding, Capacity + Duration

   • STM - Coding is mainly acoustic (Cat, Hat, Mat etc)
     • LTM - Coding is mainly semantic (Huge, Large, Big etc)
     • Baddeley 1966 - lists of different words given to PPT
       • Acoustically similar + dissimilar and semantically similar + dissimilar
         • PPT found acoustically similar harder = STM is coded acoustically
   • STM - capacity is 7 +- 2 between 5 and 9 on average
     • LTM - capacity is unlimited
     • Miller 1956
     • Evaluations
       • Study lacks validity
         • The early study lacks in control - PPT could have been distracted during the study, this would affect their performance = confounding variable
       • Cowen - found that it is only about 5 chunks - Miller's lower estimate was more accurate
   • LTM - duration is up to a life time
     • STM - duration is about 18 seconds
       • Peterson and Peterson
         • PPT given nonsense trigrams + asked to count backwards from a given number for different amounts of time
         • After 3 secs 90% recall after 18 secs 3% recall = STM lasts roughly 30secs
         • Evauluations
           • The stimuli used as artificial - they did not represent real life
             • It lacks external validity - it can not be generalised to the real world
           • Forgetting can be because of
             • Spontaneous decay - if information is not rehearsed the memory simply disappears
             • Displacement - new information pushes old information out due to the limited capacity of STM
               • Counting backwards could lead to replacement of the original information
                 • The study lacks internal validity - it was not duration being tested but it is displacement
     • Bahrick 1975