Features of LTM and STM

Question 1

What is STM?

Answer 1

Events in the present or immediate past

Question 2

What is LTM?

Answer 2

Events in the distant past

Question 3

Peterson and Peterson study of STM durration (1959)

Answer 3

Aim: Investigate duration of STM
Procedure: 24 students told nonsense trigram (WRT), then had to count backwards in 3’s or 4’s starting from 3,6,9,12 or 18 seconds
Findings: 3 seconds = 90% accuracy, 18 seconds = 2% accuracy
Conclusion: When rehearsal is prevented, STM lasts about 20 seconds

Question 4

Shepard study of LTM duration (1967)

Answer 4

Aim: Investigate duration of LTM
Procedure: Show P’s 612 memorable pictures, 1 hour later showed pictures amongst new pictures
Findings: 97% accuracy and 50% accuracy 4 months later
Conclusion: LTM memories are very long lasting

Question 5

What did Miller (1956) find out about the capacity of STM?

Answer 5

It is around 5-9 items and it can be increased by chunking separate ‘bits’ of information into larger chunks, this is because after 3 seconds, there was a 90% accuracy recall

Question 6

What is the capacity of LTM?

Answer 6

Potentially unlimited, there is no evidence to support this as it isn’t possible to test the unlimited

Question 7

Coding of STM and LTM by Baddeley (1966)

Answer 7

Aim: Test effects of acoustic and semantic similarity on STM and LTM
Procedure: 75pp’s presented with one of these four word lists
- acoustically similar words: cat, mat, sat
- acoustically disimilar words: pit, day, cow
- semantically similar words: big, huge, tall
- semantically disimilar words: hot, safe, foul
There was an interference task where pp’s had to hear and wriite numbers, in the test phase pp’s needed to recall the words in the order they appeared
Findings: STM has difficulty remembering acoustically similar words and LTM gets semantically similar words muddled up
Conclusion: STM is encoded acoustically and LTM is coded semantically

Question 8

What is the strengths of laboratory studies for memory?

Answer 8

• Reliable - can be recreated
• Good control - find out cause and effect

Question 9

What are the weaknesses of laboratory studies for memory?

Answer 9

• Ecological validity - doubt whether results reflect real life scenarios
• Inaccurate results - pp’s may alter behaviour if they know the purpose of the experiment