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Cognitive psychology:
The nature of memory: STM, LTM and duration…read more

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Duration of short-term memory
Duration is how long a memory lasts before it is no longer available.
Short-term memory does not last very long.
Short-term memory is like a notepad where we mentally scribble down things we
need to remember for just a very short period.
The way most people keep information in their STM for more than just a few
seconds is to rehearse it is one way of keeping your memory active.
Studies of duration of STM:
> Lloyd and Peterson (1959) conducted a landmark study of the duration of STM.
> The enlisted the help of 24 students attending their university.
> Recall was tested as followed:
The experimenter said a consonant syllable to the participant followed by a three-digit
number. e.g. WRT 303
> Immediately after hearing the syllable and the number, the participants had to count
backwards from this number in 3's until told to stop.
> They counted backwards because it stopped the participant rehearing the syllable
because rehearsal would aid recall.
> Participants remembered 90% when there was only a 3 second interval and about 2%
when there was an 18 second interval.
> This suggests that when rehearsal is prevented, STM lasts about 20seconds at most.…read more

Slide 3

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Duration of long-term memory
Long-term memory lasts up to 2 hours to 100 years.
Shepard (1967) showed participants 612 memorable pictures, one
at a time.
An hour later they were shown some of these pictures among a set
of others and showed almost perfect recognition.
Four months later they were still able to recognise 50% of the
Bahrick et al. (1975) showed material to be remembered was more
meaningful to the participants, and therefore the duration of the
long term memories was better.…read more

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Evaluation of STM research
They were not testing duration.
When the participants were counting backwards, the nonsense syllables
could well have been displaced in the STM by the numbers, therefore
wiping out the memory for the syllables.
It is a lab based research, therefore it has high control of variables
Using strings of consonants in a lab are not like we do in real life, the
research may lack ecological validity, as in real life we remember events
and meaningful information, thus not telling us anything useful about the
nature of memory
For example research into flashbulb memory has shown that memories
can be lot more accurate when emotion is involved than in artificial lab
based studies would suggest.…read more

Slide 5

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Cognitive psychology:
The nature of memory: capacity and encoding…read more

Slide 6

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What is capacity:
Measure of how much can be held in memory, it is
measured in terms of bits of information such as number
of digits.
The short term store has very limited capacity, about 7
items. In contrast the capacity of the long term memory is
assumed to be so large that it cannot be filled, it is said to
have unlimited capacity and lasts potentially forever.…read more

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