MEM 02 - Capacity & Duration

Question 1

What is STM?

Answer 1

The limited capacity memory store.

Question 2

What is LTM?

Answer 2

The permeanent memory store.

Question 3

What is capacity?

Answer 3

The amount of information that can be held in memory.

Question 4

What is duration?

Answer 4

The length of time information can be held in memory.

Question 5

What is capacity?

Answer 5

The format in which information is stored in various memory stores.

Question 6

Who discovered how STM and LTM are coded? And when?

Answer 6

Alan Baddeley (1966a, 1966b)

Question 7

What was the procedure of Alan Baddeley’s study?

Answer 7

He gave a list of different words to 4 groups:
- Group 1 had a list of words that sounded similar
- Group 2 had a list of words that sounded different
- Group 3 had a list of words that had similar meanings
- Group 4 had a list of words that had disimilar meanings

Participants were shown the original words and asked to list them out in the correct order.

Question 8

What is the conclusion of Alan Baddeley’s study?

Answer 8

• When they did this task immediately, recalling from STM, participants did worse with acoustically similar words.
• When they did this task after a certain interval, 20 minutes, recalling from LTM, participants tended to do worse with semantically similar words.
• This study showed that STM is coded acoustically and LTM is coded semantically,

Question 9

Who discovered the capacity of STM? And When?

Answer 9

Joseph Jacobs (1887) and George Miller (1956)

Question 10

What was the procedure of Joseph Jacob’s study?

Answer 10

• Jacobs conducted a study using a digit span test.
• He used a sample of 443 female students (aged 8-19) from the North London Collegiate School.
• Participants has to repeat back a string of numbers or letters in the same order and the number of digits/letters was gradually increased, until the participants could no longer recall the sequence.

Question 11

What was the conclusion of Jacob’s study?

Answer 11

Participants had a mean digit span of 9.3 items and a mean span of 7.3 letters.

Question 12

What was the procedure of George Miller’s study? And what did he conclude?

Answer 12

• Miller made observations of everyday practices and noticed that things come in sevens e.g. notes on a musical scale, days of the week, seven deadly sins.
• He also noticed that we recall 5 words as easily as 5 letter. We do this by chunking i.e. grouping sets of digits or letters into units or chunks.
• He concluded that the span of STM was 7+/-2 chunks or items.

Question 13

Who discovered the capcity and duration of LTM? And when?

Answer 13

Harry Bahrick et al (1975)

Question 14

What was the procedure of Bahrick’s study?

Answer 14

• He studied 392 american participants aged between 17 and 74.
• High school yearbooks were obtained from the participants or directly from some schools.
• Recall was tested in various ways e.g. photo recognition consisting of 50 photos and free recall where participants recalled all the names of their graduating class.

Question 14

What was the conclusion of Bahrick’s?

Answer 14

• Participants tested within 15 years of graduation were about 90% accurate in photo recognition.
• After 48 years, recall declined to about 70% for photo recognition.
• Free recall was less accurate than recognition - about 60% after 15 years, dropping to 30% after 48 years.
• This shows that LTM may last up to a lifetime for some material.

Question 15

Who discovered the duration of STM? And when?

Answer 15

Margaret and Lloyd Peterson (1959).

Question 16

What was the procedure for the Peterson and Peterson study?

Answer 16

• Used a lab experiment involving 24 participants who were shown trigrams which they had to recall
• They were also shown 3-digit numbers and were told to count backwards from this number.
• On each trial they were told to stop counting backwards after 3, 6, 9, 12, 15 or 18 seconds and to recall the orignally shown trigram.

Question 17

What was the conclusion of the Peterson and Peterson study?

Answer 17

Their results showed that the longer each student had to count backwards, the less well they were able to recall the trigram accurately.

• After 3 seconds 80% of the trigrams were recalled correctly.
• After 6 seconds this fell to 50%.
• After 18 seconds less than 10% of the trigrams were recalled correctly.

Question 18

What are the strengths and limitations of Baddeley’s experiment?

Answer 18

Strength: his study showed that both STM and LTM are seperate and coded differently linking to the MSM.

Limitation: his study only used meaningless words, so his study lacked ecological validity and may not tell us enough about the coding in different memory tasks.

Question 19

What makes Jacob’s study a valid study?

Answer 19

It has been replicated in a more controlled setting allowing future researchers to prove the findings of Jacob’s study.

Question 20

What are the limitations of Miller’s study?

Answer 20

• Miller’s study could be seen as exaggerated, overestimating the capacity of STM.
• Nelson Cowan (2001) reviewed other research and concluded that the capacity of STM is actually is 4+/-1 making it closer to Miller’s suggestion of 5 rather than 9.

Question 21

What are the limitations of Peterson and Peterson’s study?

Answer 21

The Petersons’ study used consonant syllables and which lacked any meaning to the participants, meaning it had poor ecological validity.

Question 22

What are the strengths of Bahrick et al’s study?

Answer 22

Bahrick used everyday real life situations and images shown in the study had actual meaning to the participants. This study had a high ecological validity.