STM & LTM

Question 1

What 3 things are the STM and LTM distinguished by?

Answer 1

capacity, duration, coding

Question 2

The capacity of short-term memory

Answer 2

• Miller (7+-2) - average span for STM is 7 items of info, but can be a little more or less

BUT
The capacity can differ depending on what we are remembering:

• Jacobs - digits are recalled better than letters (perhaps because there arE only 9 digits but 26 letters)

Question 3

Criticisms of research on the STM and LTM capacity

Answer 3

• Cowan: believes STM is limited to 4 chunks, rather than 7, based on review of other studies. Vogel at al agreed with Cowan, particularly with visual information
• Simon (1974) found that the size of the chunk impacts how many chunks you can remember (larger chunk=shorter memory) ‘7 chunks of info’ is too vague
• Jacobs also found that individual differences affect the STM, as age increases so does the capacity of our STM

Question 4

What was Peterson and Peterson’s study testing the duration of the STM?

Answer 4

• Participants were given 3 letters and asked to recall them after intervals that varied in length of time. During this interval they were asked to count backwards
• Lloyd and Peterson found that after 3 second intervals participants remembered 90% accurately, but by 9 seconds it was 20%, and by 18 seconds it was less than 2%

Question 5

What was Bahrick et al’s study testing the duration of the LTM?

Answer 5

2 groups
• Group 1: Participants were shown pictures and some were of their old yearbook. asked to recall as many names of classmates as they could
• Group 2: free recall, no pictures. Asked to name as many classmates as they could
• 15 years since graduating, accurate recall with pictures was at 90%. But by 48 years it was 70%
• free-recall group remembered less after 15 years at only 60%, and then 48 years=30%

Question 6

Evaluation of research on the duration of STM and LTM

Answer 6

• (-) the research is artificial - low mundane realism. people do not try and remember this way or do they try and remember random consonant syllables. (+) However, we do sometimes try and remember meaningless letters and numbers e.g phone numbers and postcodes, so does reflect real like a little bit
• peterson & peterson’s results could be due to displacement rather than decay

Question 7

What 3 types of coding are there?

Answer 7

• acoustic coding
• visual coding
• semantic coding

Question 8

What was Baddeley’s study on semantic and acoustic coding?

Answer 8

• gave participants word lists. STM tested by immediate recall LTM tested by waiting 20 minutes for recall
• used semantically similar words (big, large, great, huge) and used acoustically similar words (mad, max, man, map)
• they showed more difficultly remembering acoustically similar words in STM rather than LTM, but more difficulty remembering semantically similar words in LTM rather than STM
• suggests STM is largely encoded acoustically but LTM is largely encoded semantically

Question 9

Evaluation of coding research on STM and LTM

Answer 9

• (-) waiting 20 minutes before recall when testing LTM may have been too short of a time for it to be truly testing the LTM. May still be in short term
• LTM may not be entirely semantically coded, could have visual coding (Frost 1972) and even some acoustic (Rothbart 1972)