PSYCHOLOGY PAPER 1- MEMORY
The Multi Store Model of Memory
Short-term memory (STM) definition-
Your memory for immediate events, which disappear if not rehearsed. It is sometimes called
working memory.
Long-term memory (LTM) definition-
Your memory for events that have happened in the past from anywhere between 2 minutes
and 100 years ago. It is the permanent memory store.
Sensory register-
The sensory register is a storage system that receives information from the sense organs. It
is not under cognitive control, but is an automatic response to the reception of sensory
information. If information is paid attention to it passes on to the next store – short term
memory. If not paid attention to, the information fades away quickly through trace decay
leaving no lasting impression.
Capacity definition-
The amount of information that can be stored
Duration definition-
The length of time information can be held in the memory store
Coding definition-
The format in which information is stored in the memory stores (e.g. acoustic, semantic). It’s
the process of converting information from one format to another.
Acoustic coding definition-
Means that information is stored in the form of sounds.
Semantic coding definition-
Means that information is stored in the form of the meaning of the experience.
Different types of sensory coding-
Iconic (visual), echoic (auditory), haptic (touch), gustatory (taste), olfactory (smell)
Research into coding in the multi-store model of memory
Crowder (1993) provides research evidence for different types of coding in the sensory
register. Crowder found that the sensory register retains iconic information for a few
milliseconds but echoic information for 2-3 seconds. This suggests there are different stores
within sensory memory so different types of coding exist too.
Research into capacity in the multi-store model of memory
Sperling (1960) provides research evidence that the capacity of each memory store within
the sensory register is quite large. Sperling studied the iconic store of sensory memory by
flashing a 3x4 grid of letters onto a screen for 1/20th of a second & asked participants to
,recall the letters of one of the rows. As the information would fade very quickly he followed it
immediately with a tone (high, medium or low) to indicate which row had to be recalled (1st,
2nd or 3rd). Recall of letters in the indicated row was high (76% on average). This suggests
that all of the information was originally there, indicating that the capacity of the sensory
register (especially for the iconic store) is quite large. Thus, the capacity of each sensory
memory store must be very large as the information contained within them is in
unprocessed, highly detailed and ever-changing formats.
Research into duration of the multi-store model of memory
Sperling (1960) provides research evidence that the duration of each memory store within
the sensory register is limited. Sperling varied the conditions of his original experiment by
delaying the time between showing the letters and giving the tone. If there was a delay
between the presentation of the grid and the sounding of the tone, more and more
information was lost. Only 50% available after 0.3 second delay, only 33% available after 1
second delay. This suggests that the duration of the sensory register is only about 1 second.
Thus, it appears that all sensory memory stores have a limited duration, though the actual
duration of each is not constant – different types of information decaying at different rates.
Different sensory stores appear to have different capacities and there is some evidence that
duration decreases with age.
The capacity of the STM- research
The capacity of STM can be assessed using digit span. In one of the earliest studies in
Psychology, Jacobs (1887) used this technique to assess STM capacity. He found that the
average span for digits was 9.3 items and for letters was 7.3 items (Jacobs suggests it is
easier to recall digits because there are only 9 of them, whereas there are 26 letters). To
measure digit span, the researcher gives, for example, four digits and then the participant is
asked to recall these in the correct order out loud. If the participant is correct, the researcher
reads out five digits, and so on. When participants fail to recall no more than 50% of the digit
string they are judged to have reached their capacity. Miller (1956) wrote a memorable
article called ‘The magic number seven plus or minus two’, in which he reviewed
psychological research and concluded that the span of STM is about seven items –
sometimes a bit more, sometimes a bit less (7+2). The same is true if you are asked to recall
musical notes, letters and even words. Miller found that people can recall five words as well
as they can recall five letters – we chunk things together and can then remember them – a
process known as ‘chunking’.
Evaluation of research into capacity of STM
● The capacity of STM may be even more limited as Miller’s findings have not been
replicated. Cowan (2001) reviewed a variety of studies on the capacity of STM and
concluded that STM is likely to be limited to about 4 chunks Research on the
capacity of STM for visual information (rather than verbal stimuli) also found that 4
items was about the limit (e.g. Vogel et al., 2001) This means that the lower end of
Miller’s range is more appropriate (i.e. 7-2=5) This suggests that STM may not be as
extensive as was first thought.
● It seems that the size of the chunk affects how many chunks you can remember
Simon (1974) found that people had a shorter memory span for larger chunks, such
as 8 word phrases, than smaller chunks, such as one-syllable words This continues
to support the view that STM has a limited capacity but further refines our
understanding – the size of the chunk matters.
● There are individual differences in terms of the capacity of STM – it is not the same
for everyone. Jacobs also found that recall (digit span) increased steadily with age; 8
year olds could remember an average of 6.6 digits 19 year olds could remember a
, mean of 8.6 digits. This increase with age might be due to changes in brain capacity
and/or the development of strategies such as chunking This suggests that the
capacity of STM is not fixed and individual differences may play a role
Research into the capacity of LTM
Procedure: Wagenaar (1986) created a diary of 2,400 events over six years and tested
himself on recall of events (rather than dates).
Findings: He had an excellent recall of the events.
Conclusion: LTM capacity is extremely large, potentially unlimited.
Research into the capacity of LTM- evaluation
● Supporting evidence- Anokhin (1973) supports the conclusions of this study. He
estimated the number of possible neuronal connections in the human brain is 1
followed by 10.5 million kilometres of noughts. He concluded that ‘no human yet
exists who can use all the potential of their brain’. This suggests that the capacity of
LTM is limitless.
● BUT this is a case study, not generalizable.
STM- duration research
A lab experiment was conducted in which 24 undergraduate students took part in 8 trials (8
tests). On each trial they were given a consonant trigram (meaningless three-consonant
syllables, e.g. TGH) to remember and a three-digit number. The students were then asked to
count backwards from the number in either 3s until told to stop. The counting backwards was
to prevent any mental rehearsal of the consonant syllable (which would increase the
student’s memory). On each trial, they were told to stop after a different amount of time - 3,
6, 9, 12, 15 or 18 seconds. This is called a retention interval. After this, they were asked to
stop counting and to repeat the trigram. The percentage of trigrams correctly recalled was
recorded for each retention interval. Findings: The longer the interval delay the less trigrams
were recalled. Participants were able to recall 90% of trigrams after a 3 seconds delay, 20%
after 9 seconds and 2% after 18 seconds. Conclusion: Short-term memory has a limited
duration (up to 18 seconds) when verbal rehearsal is prevented. The results of the study
also show short-term memory is different from long-term memory in terms of duration.
STM duration research evaluation
● A criticism of this research is that investigating STM in this way is rather artificial.
Trying to memorise consonant trigrams does not reflect most everyday memory
activities where what we are trying to remember is meaningful. However, we do
sometimes try to remember fairly meaningless things such as groups of numbers
(phone numbers) or letters (postcodes). Thus, although the task is rather artificial, the
study does have some relevance to everyday life.
● A criticism of the Petersons’ study is that it did not actually measure what it set out to
measure (lacks internal validity). When the participants were counting down the
numbers in their STM this may have displaced or ‘overwritten’ the trigrams to be
remembered. Thus, the forgetting in the Petersons’ study may have been due to
displacement rather than decay.
LTM- duration research
Participants were an opportunity sample of 392 American ex-high school students aged
17-74 years. High school yearbooks were obtained from the participants directly or from
some schools. Recall was tested in various ways, including: (1) free recall test - where
participants recalled the names of as many of their former classmates as possible; (2) photo
recognition test - where they were asked to identify former classmates in a set of 50 where
some were from their yearbook and some weren’t. Findings: Participants who were tested
within 15 years of graduation were about 90% accurate in photo recognition. After 48 years,
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