A* revision notes for memory, a compulsory topic for both AS and A level AQA Psychology, containing all necessary and detailed definitions, explanations and case studies. Best results when used alongside Exampro Exam Questions for memory that are available free of charge online with mark schemes a...
Memory Revision Notes
Coding, capacity and duration:
- Coding refers to the format in which information is stored in the various memory stores.
- Capacity refers to the amount of information that can be held in a memory store.
- Duration refers to the length of time information can be held in a memory store.
Research on coding
AO1:
Baddeley (1966) carried out a recall task in which he gave different lists of words to four
groups of participants to remember. Group 1 had acoustically similar words, group 2 had
acoustically dissimilar words, group 3 had semantically similar words and group 4 had
semantically dissimilar words. Then, the participants were asked to recall the words in the
correct order. When this task was done immediately, recalling them from short-term memory,
the participants tended to do worse with acoustically similar words. When 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 therefore suggest that information is
coded acoustically in STM and semantically in LTM.
AO3:
+ One strength of Baddeley’s study is that it identified a clear difference between the two
memory stores. Furthermore, the idea that short-term memory is coded acoustically and
long-term memory is coded semantically has been supported by other evidence. This has
also developed our understanding of the memory system, which has led to the multi-store
model.
- One limitation of Baddeley’s study was that it was an artificial stimulus. For example, the
word lists had no personal meaning to participants. Therefore, Baddeley’s findings do not tell
us much about coding in different kinds of memory tasks, especially in everyday life. This
suggests that the findings from this study have limited application.
Research on capacity
AO1:
Jacobs (1887) carried out a digit span study in which a researcher read out four digits and
asked the participant to recall them out loud. If the digits were recalled correctly, the
researcher read out five digits and so on until the participant could not recall the order
correctly. This indicated the individual’s digit span. Jacobs found that the mean digit span
across all participants was 9.3 items and the mean span for letters is 7.3 items.
AO3:
+ One strength of Jacobs’ study is that it has been replicated. This suggests that his study is
a valid test of digit span in short-term memory.
- As this study is old, it is likely that Jacobs’ study lacked adequate controls. For example,
some participants’ digit spans might be underestimated because they were distracted during
testing (confounding variable).
, AO1:
Miller (1956) made observations of everyday practice and suggested that the capacity of
short term memory is about 7 +/- 2 items as many things come in sevens e.g. seven days of
the week and seven notes on the musical scale. Unlike Jacobs, he suggested that people
can recall letters as easily as numbers. This can be done by a process called chunking
which involves grouping sets of letters or digits into units or chunks.
AO3:
- One limitation of Miller’s research is that he may have overestimated short-term capacity.
For example, Cowan reviewed other research and concluded that the capacity of short-term
memory is approximately 4 items, meaning that the lower end of Miller’s estimate (five items)
is more appropriate than seven items.
Research on duration:
AO1:
Peterson and Peterson (1959) tested the duration of short-term memory. 24 participants
were given a consonant syllable to remember in eight trials. The participant then counted
backwards from a three-digit number given until they were told to stop as this prevented
maintenance rehearsal. After 3 seconds, the average recall was 80% and after 18 seconds it
was approximately 3%. Peterson and Peterson’s findings suggested that short-term memory
duration may be around 18 seconds, unless rehearsal (i.e. verbal rehearsal) is carried out.
AO3:
- One limitation of Peterson and Peterson’s study was that it was an artificial stimulus. This is
because recalling consonant syllables does not reflect most everyday memory activities
where we are attempting to remember meaningful material. This means that the study
lacked external validity.
AO1:
Bahrick (1975) studied 392 American students aged between 17 and 74. Recall was tested
in various ways, including: (1) photo-recognition test consisting of 50 photos, some from the
participants’ high school yearbooks, (2) free recall test where participants recalled all the
names of their graduating class. 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 photo recognition - about 60% after 15 years,
dropping to 30% after 48 years. This shows that long-term memory may last up to a lifetime
for some material.
AO3:
+ One strength of Bahrick’s study is that it has high external validity. This is because the
researchers investigated meaningful memories i.e. people’s names and faces. 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
long-term memory.
- One limitation of Bahrick’s study was that there was inadequate control over some
variables. For example, students who kept in touch with their graduating class were more
likely to remember the names and faces than students who did not. However, this does not
necessarily mean that the duration of their long-term memory is higher in all scenarios.
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