Miller (STM Capacity)
- Proved that STM had a capacity of 5-9 items using the digit span technique with immediate serial recall.
- Read aloud a digit string to pps, starting with 3 numbers, increasing each time up to 11. (Changed the numbers to prevent practice).
- pps repeated back (verbally) the digit string they just heard in the correct order.
- Miller found that STM capacity ranged between 5-9 items - supporting the STM capacity.
- AO2 - Lab exp (all strengths & weaknesses specific to the study)
Bahrick (LTM Duration)
- Proved that duration of LTM lasted up to a lifetime using the high school year book photographs.
- (longitudinal) Graduates from a high school over a 50yr period.
- Split graduates into two groups to test recall duration.
- Recall group - identified people in photographs
- Recognition group - matched names to the faces. <—This group were best at recalling names.
- Recog: After 14yrs - 90% accurate - 60% accurate after 47yrs
- Recall: 60% accurate after 7yrs - 20% accurate after 47yrs
- Showing LTM duration is long.
AO2 - High eco val (real life)
AO2 - 47yrs might be an early cut off point to represent a lifetime of memory - doesn’t consider the natural decline of memory with age.
Peterson & Peterson (STM Duration)
- Proved that STM duration was no longer than 30 seconds.
- Quickly showed pps consonant trigrams.
- pps were asked to count backwards in 3’s from desired number (prevent rehearsal).
- Pete&Pete asked them to recall trigram after 3,6,9,12,15 and 18 seconds.
- Found that after 3secs recall v good (80% of trigrams remembered). After 18secs fewer than 10% were remembered.
- Therefore STM duration isn’t much longer than 18 secs.
AO2 - Lab exp (all strengths & weaknesses specific to the study)
HM & Clive Wearing - cases of Amnesia (Different s
Had severe brain damage to hippocampus (LTM).
Both lost ability to form new long-term memories.
However STM worked fine.
This provides strong neuropsychological evidence that STM and LTM are different stores in the brain as only LTM was affected.
AO2 - High in eco val, very useful,
AO2 - Ethics
AO2 - sample size of 1 - can’t generalise
Brain Scans (Distinction between stores)
- Activity is shown in hippocampus when LTM tasks are carried out.
- (Explains why damage to hippocampus causes LTM impairment.)
- Activity is shown in prefrontal cortex when STM tasks are carried out.
- Suggesting two different stores - adding validity to MSM.
AO2 - Scientific, objective