Coding, Capacity And Duration Of Memory

Question 1

Research on Coding

Answer 1

The process of converting information between different forms is called coding.
Alan baddeley gave different lists of words to four groups of participants to remember:
- acoustically similar
- acoustically dissimilar
- semantically similar
- semantically dissimilar
Participants were shown the original words and asked to recall them in the correct order. When they did this task immediately, recalling from short term memory, they tended to do worse with acoustically similar words. Whe they recalled the word list after a time interval of 20 minutes, recalling from long term memory, they did worse with the semantically similar words. These findings suggest that information is coded acoustically in the STM and semantically in the LTM.

Question 2

Research on Capacity

Answer 2

Digit Span:
How much information can STM hold at one time - what is its capacity?
Joseph Jacob’s (1887) found out by measuring digit span. For example, the researcher reads out four digits and the participant recalls these out loud in the correct order. If this is correct the researcher reads out five digits until the participant cannot recall the order correctly. This indicates the individuals digit span.
Jacob’s found that the mean span for digits across all participants was 9.3 items. The mean span for letters was 7.3.

Span of memory and chunking:
George Miller (1956) found that people can recall five words just as easily as five letters. We do this by chunking - grouping sets of digits or letters into units or chunks.

Question 3

Research on Duration

Answer 3

Duration of STM:
24 students given a consonant syllable and a 3 digit number
Student had to count backwards to prevent any mental rehearsal
Told to stop after varying times (3,6,9,12,15,18 seconds)
Findings showed that after 3 seconds recall was 80%, whereas after 18 seconds recall was 3%
Peterson and Petersons findings indicated that STM duration may be about 18 seconds, unless we repeat the information over and over

Duration of LTM:
392 American students
photo recognition as well as/or free recall for as many names of their graduating class as possible
Participants within 15 years of graduation were about 90% accurate and 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 4

Evaluation for research on coding

Answer 4

Separate memory stores:
- Baddeley showed clear difference between the two memory stores
- STM is acoustic and LTM is semantic (mostly)
This was an important step in our understanding of the memory system, which ket to the multi - store model

Artificial stimuli:
- Baddeley’s lists had no personal meaning to participants, so his findings may not tell us much about coding in different kinds of memory tasks, especially in everyday life
- When processing more meaningful information, people may use semantic coding even for STM tasks
This suggests that the findings from the study have limited application

Question 5

Evaluation for research on capacity

Answer 5

A valid study:
- strength of Jacob’s study is that it has been replicated more recently with control of confounding variables such as participants being distracted during testing
This suggests that Jacob’s study is a valid test of digit span in STM

Not so many chunks:
- one limitation of Miller’s research is that he may have overestimated STM capacity
- other psychologists have reviewed other research and concluded that the capacity of STM is only about 4 (plus or minus 1) chunks
This suggests that the lower end of Miller’s estimate (five items) is more appropriate than seven items

Question 6

Evaluation for research on duration

Answer 6

Meaningless stimuli in the STM study:
- one limitation of Peterson and Peterson’s study is that the material is artificial
- does not reflect everyday life/ meaningful memory activities where what we are trying to remember something meaningful
This means the study lacked external validity

High external validity:
- Bahrick’s study has high external validity because the researchers investigated meaningful memories (names and faces of people)
- when studies on LTM were conducted with meaningless pictures to be remembered, recall rates were lower
This suggests that Bahrick’s findings reflect a more ‘real’ estimate of the duration of LTM