Slides in this set
Short term, long term and duration.
Short term Long term
· Short term memories do not last · Long term memories last anywhere
very long. from 2 hours to 100 years.
· An example of the short term · Shepard (1967) tested the duration
memory in action would be trying of the LTM. He presented
to remember a phone number. This participants 612 memorable
is maintained by repetition until pictures one at a time. An hour
dialled and this is then forgotten as later, there was almost perfect
the conversation begins. recall of the photographs and four
· Rehearsal is one way of keeping a months later, participants still
memory active. recognised 50% of the
· The result of such verbal photographs.
rehearsal is that short term · Bahrick et al. also conducted a
memories are held in the short study in 1975 asked participants of
term memory store and eventually varying ages to name the people
become long term. from their high school yearbook. 48
years on, people were still 70%
Study on the duration of STM
Lloyd and Margaret Peterson (1959)
· The experimenter said a consonant Results
syllable to the participant, followed · Participants remembered about
by a three digit number (e.g. WCR 90% when there was only a 3
204). The syllable was meant to second interval and about 2% when
have no meaning. there was an 18 second interval.
· Immediately after hearing the · This suggests that when rehearsal
syllable and number, the is prevented, STM lasts about 20
participants had to count backwards seconds at most.
from the number in 3s or 4s until
they were told to stop. This is a
distraction activity to prevent the
rehearsal of the syllable.
· The participant was asked to recall
the nonsense syllable.
· Each participant was given two
practice trials before eight trials. On
each trial the retention interval was
different: 3, 6, 9, 12, 15 or 18
The duration of STM may be even Not quite so short term memory.
shorter. · More recent research has shown
· Peterson and Peterson's results that the duration of STM is not as
have been challenged. It could be short as Peterson and Peterson's
argued that in this experiment, study.
participants were relying on more · Nairne et al.'s 1999 study found
than STM alone because they that items could be recalled as long
knew they would be asked to recall as 96 seconds later. In Nairne's
the item. study, participants were asked to
· Other research (Marsh et al., 1997) recall the same items across trials,
has suggested that when whereas in the earlier studies,
participants do not expect to be different items were used on each
tested, forgetting can occur as trial, which led to interference and
quickly as 2 seconds later. decreased recall.…read more
Capacity of the STM.
· Joseph Jacobs (1887) used the Evaluation
`digit span technique' to assess the · Cowan (2001) reviewed a
capacity of the STM. He found that multitude of studies on the capacity
the average span for digits was 9.3 of the STM. His conclusion was
items, whilst it was 7.3 items for that the STM is likely to be limited
letters. He suggested that this was to 4 chunks.
because there are only 9 digits but · Some researchers have also
26 letters. looked at the capacity of the STM
Increasing the capacity of the STM for visual information (rather than
· George Miller (1956) wrote an verbal) and found that 4 items was
article, reviewing psychological about the limit (Vogel et al., 2001).
research and concluded that that
the span of immediate memory is
seven. He also found that people
can remember five words as well
as they can five letters (because
we chunk information).…read more
Short-term memory your Capacity a measure of how
memory for immediate events. The STM much can be held in memory. It is
has limited duration and capacity. This measured in terms of bits of
type of memory is often referred to as information, such as a number of
working memory, because it is used in a digits.
comprehending language, solving
Long-term memory your
memory for events that have happened
in the past. This can last from 2 minutes
to 100 years. The long term memory
store has potentially unlimited capacity
Duration A measure of how
long a memory lasts before it is no longer