2.1 Coding, Capacity and Duration

2.1 Coding, Capacity and Duration

1. Coding

   • Baddeley (1966)
     • Gave lists of words to 4 groups of participants which were 1. acoustically similar 2. acoustically dissimilar 3. semantically similar 4. semantically dissimilar
     • STM - acoustically coded
     • LTM - semantically coded
     • Evaluation
       • Strength: Identified a clear difference between the LTM and STM. Led to the multi-store model.
       • Weakness: Used artificial stimuli rather than meaningful material. Word list had no personal meaning to the participants.

2. Capacity

   • Jacobs (1887) Digit span
     • STM- Found that the mean span of digits stored was 9.3 and mean span for letter was 7.3
   • Miller (1956) Span of memory
     • STM can only 7+/- 2 items
   • Evaluation
     • Strengths:
       • Jacobs study can be replicated. His findings have been confirmed by other researchers, meaning it is a valid test of digit span.
     • Weaknesses:
       • Miller's research may have overestimated stm capacity. Cowan reviewed other research and found that STM is only 4+/- 1 chunk.

3. Duration

   • STM
     • 0-18 seconds
     • Peterson and Peterson (1959) tested 24 students, each student was given a consonant syllable and a 3 digit number.
   • LTM
     • Unlimited
     • Bahrick et al (1975) showed American participants between 17-74 their highschool yearbook. Tested in two ways, photo recognition and recalling names. Those tested within 15 years of graduation were about 90% accurate, after 48 years recall dropped to 70%.
   • Evaluation
     • Strengths:
       • High external validity. Bahrick's study includes meaningful memories so there is a real estimate to the duration of LTM.
     • Weaknesses:
       • Meaningless stimuli in STM study. Peterson and Peterson study used consonants which do not reflect everyday memory.