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.
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.
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.