Coding capacity and duration of memory

Question 1

Separate memory stores

Answer 1

One 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 the multi-store model

Question 2

Artificial stimuli

Answer 2

One limitation of Baddeley’s study was that it used quite artificial stimuli rather than meaningful material.
For example, the word lists had no personal meaning to participants.
So 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.
This suggests that the findings from this study have limited applications

Question 3

A valid study

Answer 3

One 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. For example, 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 (e.g. Bopp and Verhaeghen 2005).
This suggests that Jacobs’ study is a valid test of digit span in STM

Question 4

Not so many chunks

Answer 4

One limitation of Miller’s research is that he may have overestimated
STM capacity.
Nelson Cowan (2001) 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 5

Meaningless stimuli in STM study

Answer 5

One limitation of Peterson and Peterson’s study is that the stimulus material was artificial
The study is not completely irrelevant because we do sometimes try to remember fairly meaningless material (e.g. phone numbers). Even so, recalling consonant syllables does not reflect most everyday memory activities where what we are trying to remember is meaningful.
This means the study lacked external validity.

Question 6

High external validity

Answer 6

One strength of Bahrick et al’s study is that it has high external validity.
This is because the researchers investigated meaningful memories (i.e. of people’s names and faces). When studies on LTM were conducted with meaningless pictures to be remembered, recall rates were lower (e.g. Shepard 1967).
This suggests that Bahrick et al’s findings reflect a more ‘real’ estimate on the duration of LTM