Transcript Presentation2 short term memory

Duration is the amount of time a memory lasts in out
short term memory.
The duration of Short Term Memory lasts up to about
18-20 seconds and occasionally goes up to 30 seconds.
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An experiment conducted by Margret and Lloyd
Peterson in 1959. Participants were given were
given trigrams these are (meaningless groups of
three letters) to memorise. For example items such
as qlg, jmb and mwt. Immediately after the
trigrams were presented the participants were
given a distracter or an interference task, where
they required to starting counting backwards by
threes from a three digit number for example: 634,
631 and 628. This was done to prevent rehearsal of
trigrams. Following a time interval that varied
from 3 to 18 seconds a light was used to signal that
participants were required to recall the trigrams.
The graph shows the longer the interval,
the less likely a participant was to
accurately recall a trigram. By 18 seconds
after the presentation of the trigrams,
participants had forgotten almost all of the
trigrams. When participants did not have
to count backwards, their performance was
much better possibly because they were
rehearsing the items to themselves. In
similar conditions if you repeat a telephone
number over to yourself it can be retained
in the Short Term Memory indefinitely. But
if you look up a telephone number and
then get distracted, you are likely to forget
the number almost immediately.
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Capacity - the amount of information we can
hold at any one time
STM is very limited in storage capacity
compared to sensory memory and long term
memory. Rarely are we able to hold more
than between 5 and 9 bits of information in
STM at any given time regardless of the
nature of that information. The limit of STM
is described as having a range of 7+2 items of
information.
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Example - read the following numbers, one at
a time, and then (without looking at them)
write them immediately on a piece of paper:
7,2,9,4,1,8,3.
Next read the following numbers, at one time,
immediately from memory: 4,9,1,7,3,8,6,3,9,5,7
If you have 'average' STM storage capacity,
you were probably able to recall the seven
numbers in the first set but not all of the 11
numbers in the second set.
Estimates of the capacity of STM are obtained by asking research
participants to memories simple lists of data of different lengths; for
example randomly ordered numbers, letters, nonsense syllables or
unrelated words. the length of the list that the participants can recall half the
time is considered to represent the capacity of short term memory.
Space in STM is filled when we think and when information is temporarily
brought from LTM into working memory to be used or updated. This is why
you cannot remember the telephone number you have just looked up if you
begin thinking about what you might say before you dial the number.
Information stored in STM is lost primarily through decay (not being used)
and displacement (being pushed out) by new information. Decay of
information in STM occurs when you forget what you want to say in a
conversation while you wait for another person involved in the conversation
to finish what they are saying. Your thoughts quickly fade from STM
because listening to what the speaker is saying prevents you from
rehearsing and therefore maintaining in STM the point you wanted to make.
It is difficult for us to think about problems involving more than 7+2 issues
(items). We forget some aspects of the problem because they exceed the
capacity of STM. in such situations, writing down all the points to be
considered prevents the information from being lost while the central
executive in your working memory is focused on another aspect of the
problem.
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Chunking is the grouping of separate bits of
information into chunks of information.
E.g.. A sequence of letters
‘D N V R C E W V D C S V’
These will be hard to remember as they are 12
separate pieces of information.
However we can remember them as chunks if
we see them like this ‘NSW VCR VCE DVD’
we now see them as four separate chunks.
Chunking requires fewer eye movement and
the brain processes the chunks as units rather
than individuals, making it easier to
remember.
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INFORMATION CAN BE KEPT IN STM FOR
LONGER THAN THE USUAL MAXIMUM OF
ABOUT 20 SECONDS,IF IT IS REHEARSED IN
SOME WAY. IN THE STUDY OF MEMORY
REHEARSAL IS THE PROCESS OF ACTIVELY
MANIPULATING INFORMATION SO THAT
IT CAN BE RETAINED IN MEMORY.
THERE ARE TWO MAIN TYPES OF
REHEARSAL: MAINTENANCE REHEARSAL
AND ELABORATIVE REHEARSAL.
Maintenance rehearsal=Involves repeating the
information being remember over and over again to
retain in STM. maintenance rehearsal can either be
verbal (words),sub-vocally(silently repeating the
information if your head), or non-verbal(involving
visual or spatial information).
Elaborative rehearsal: when represented with new
information that will be tested at a later date, many
students think That repeating the information over
and over again will assist them to retain the info in
LTM. Elaborative rehearsal involves organizing and
dealing with information in terms of its meaning.
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Consolidation theory: proposes that physical
changes to the neurons in the brain occurs due
to someone learning something new and
immediately following learning. These changes
occur for a period of time after learning takes
place, as the new information consolidates (or
sets) in memory.
Consolidation: To bring together into a single
whole or system. (to finalise)
So in other words, when we all learn something new, the neurons
in our brain become active as we take in the new info (whether it
be before or after), and not long after we store it into our memory.
The changes in our brain is the process of storing that new learned
information as memory, where it can be retrieved later on or stored
as it is. This is CONSOLIDATION THEORY.
It is the learning of short-term memory into Long-term memory
It is also proposed that if the memory is disrupted (eg-your trying to
consolidate a school fight) during our consolidation phase,
information may not process through to long-term memory and will
therefore be lost. (eg- a friend from school comes over to you and
talks about something far more interesting, therefore prohibiting the
brain from finalising the fight that had happened and focusing on
the story being told by the friend.)
However, if disruption does not occur, we can assume that the
information being finalised has been stored into long-term memory.
Consolidation of information is a gradual process and takes 30
minutes to do so thus leaving the brain vulnerable to disruption
during those 30 minutes. Additionally, the consolidation of memory
can proceed for many years once stored safely!
For example
The consolidation of STM to LTM can be compared with writing your
name in wet concrete. Once the concrete has "set" (the info
consolidated into LTM), your name (the information) is permanent.
But while it is setting (the process of consolidation), it can be
interefered with (altered) or erased (completely lost).