Memory Revision Notes
Coding, Capacity and Duration of Memory
duration can last for up to a lifetime.
Research On Coding:
-
• Coding is the format in which information is stored in the various memory stores.
Baddeley (1966) gave different lists of words to four groups of participants to remember:
- Group 1 (acoustically similar): words sounded similar (e.g. cat, cab)
- Group 2 (acoustically dissimilar): words sounded different (e.g. pit, few)
- Group 3 (semantically similar): words with similar meanings (e.g., great, large)
• Group 4 (semantically dissimilar): words with different meanings (e.g. good, hot)
• Participants were shown the original words and asked to recall them in the correct
order.
• When they did this task immediately, recalling from STM, they tended to do worse
with acoustically similar words.
• When they recalled the word list after a time interval of 20 minutes, recalling from
LTM, they did worse with the semantically similar words.
• These findings suggest that information is coded acoustically in STM and
semantically in LTM.
,Evaluation:
Separate Memory Stores
•
• Strength of Baddeley's study is that it identified a clear difference between two
memory stores.
• Later research showed that there are some exceptions to Baddeley’s findings.
• But the idea that STM uses mostly acoustic coding and LTM mostly semantic has
stood the test of time.
• This was an important step in our understanding of the memory system, which led to
the multi-store model.
Artificial Stimuli
•
• Limitation of Baddeley's study was that it used quite artificial stimuli rather than
meaningful material.
• E.g. The word lists had no personal meaning to participants.
• Baddeley's 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.
• Suggests that the findings from this study have limited application.
,Research on Capacity:
Digit Span:
•
• Jacobs (1887) found out the capacity of STM by measuring digit span.
• E.g. The researcher reads out four digits and the participant recall these out loud in
the correct order. If this is correct the researcher reads out five digits and so on until
the participant cannot recall the order correctly.
• Jacobs 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:
•
• Miller (1956) made observations of everyday practice.
• E.g. He noted that things come in sevens: seven notes on the musical scale, seven
days of the week, etc.
• Miller thought that the span (capacity) of STM is about 7+/-2. He also noted that
people can recall five words as easily as they can recall five letters.
• This is done by chunking - grouping sets of digits or letters into units or chunks.
, Evaluation:
A Valid Study
•
• Strength of Jacobs' study is that it has been replicated.
• The study is a very old one and early research in psychology often lacked adequate
controls.
• E.g. Some participants' digit spans might have been underestimated because they
were distracted during testing (confounding variable).
• Despite this, Jacobs' findings have been confirmed by other, better controlled
studies since (Bopp and Verhaeghen 2005).
• Suggests that Jacobs' study is a valid test of digit span in STM.
Not So Many Chunks
•
• Limitation of Miller's research is that he may have overestimated STM capacity.
• Cowan (2001) reviewed other research and concluded that the capacity of STM is
only about 4+/-1 chunks.
• Suggests that the lower end of Miller's estimate (five items) is more appropriate
than seven items.
Coding, Capacity and Duration of Memory
duration can last for up to a lifetime.
Research On Coding:
-
• Coding is the format in which information is stored in the various memory stores.
Baddeley (1966) gave different lists of words to four groups of participants to remember:
- Group 1 (acoustically similar): words sounded similar (e.g. cat, cab)
- Group 2 (acoustically dissimilar): words sounded different (e.g. pit, few)
- Group 3 (semantically similar): words with similar meanings (e.g., great, large)
• Group 4 (semantically dissimilar): words with different meanings (e.g. good, hot)
• Participants were shown the original words and asked to recall them in the correct
order.
• When they did this task immediately, recalling from STM, they tended to do worse
with acoustically similar words.
• When they recalled the word list after a time interval of 20 minutes, recalling from
LTM, they did worse with the semantically similar words.
• These findings suggest that information is coded acoustically in STM and
semantically in LTM.
,Evaluation:
Separate Memory Stores
•
• Strength of Baddeley's study is that it identified a clear difference between two
memory stores.
• Later research showed that there are some exceptions to Baddeley’s findings.
• But the idea that STM uses mostly acoustic coding and LTM mostly semantic has
stood the test of time.
• This was an important step in our understanding of the memory system, which led to
the multi-store model.
Artificial Stimuli
•
• Limitation of Baddeley's study was that it used quite artificial stimuli rather than
meaningful material.
• E.g. The word lists had no personal meaning to participants.
• Baddeley's 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.
• Suggests that the findings from this study have limited application.
,Research on Capacity:
Digit Span:
•
• Jacobs (1887) found out the capacity of STM by measuring digit span.
• E.g. The researcher reads out four digits and the participant recall these out loud in
the correct order. If this is correct the researcher reads out five digits and so on until
the participant cannot recall the order correctly.
• Jacobs 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:
•
• Miller (1956) made observations of everyday practice.
• E.g. He noted that things come in sevens: seven notes on the musical scale, seven
days of the week, etc.
• Miller thought that the span (capacity) of STM is about 7+/-2. He also noted that
people can recall five words as easily as they can recall five letters.
• This is done by chunking - grouping sets of digits or letters into units or chunks.
, Evaluation:
A Valid Study
•
• Strength of Jacobs' study is that it has been replicated.
• The study is a very old one and early research in psychology often lacked adequate
controls.
• E.g. Some participants' digit spans might have been underestimated because they
were distracted during testing (confounding variable).
• Despite this, Jacobs' findings have been confirmed by other, better controlled
studies since (Bopp and Verhaeghen 2005).
• Suggests that Jacobs' study is a valid test of digit span in STM.
Not So Many Chunks
•
• Limitation of Miller's research is that he may have overestimated STM capacity.
• Cowan (2001) reviewed other research and concluded that the capacity of STM is
only about 4+/-1 chunks.
• Suggests that the lower end of Miller's estimate (five items) is more appropriate
than seven items.
