Chapter 8
• Psychologists have made many
correlations between the human
brain and computers. They do not
think that they operate in the same
way. They do not, of course.
• With a computer, there are three
systems to gaining new information:
input, storage, and retrieval.
• This is somewhat like how human
beings gain new information. When
humans process new information, it
is raw sensory information that must
be coded – in sound, visual, or
meaning, that can be used in the
next stage of memory.
• Then, the information might be transferred into a
more permanent memory storage. When the
information is needed, it can be retrieved from
memory. With computers and human memory,
information can be lost.
• Some incoming information is stored for only brief
periods of time, whereas other information needs
to be tucked away permanently.
• Stage theory of memory – assumes that we
humans have a three-stage memory that meets our
need to store information for different periods of
time.
• We seem to have three memory systems: 1) holds
information for brief intervals, 2) for no more than
30 second, and 3) a more permanent memory
store.
• These are not thought of as three separate
systems, but information has to go through one to
make it to another. The first memory stage is
called the sensory register, then the short-term
memory, and long-term memory.
• The sensory register is a very brief
stage. This is designed to hold each
sensory experience until it can be
fully processed.
• We hold information in this stage
long enough to take a snapshot of
the information that we need in
order to send the important
information to the next stage.
• The snapshot goes away very
quickly, within a couple of seconds.
• For auditory information, a
recording of the sound that we
heard is there for a second or two.
• When information is selected for
further processing, it is
transferred into the short-term
memory, or STM.
• Just paying attention is enough to
transfer it.
• Once information has been
transferred into short-term
memory, a variety of control
processes may be applied.
Rehearsal and chunking are two
examples of these control
processes.
• Information is lost within the STM
in less than thirty seconds unless it
is renewed. Generally, it is lost
within seconds.
• Information in this system can be
renewed by mental repetition or
by rehearsal of the information.
• The information stored can be
quite different given memories:
the smell of perfume, the notes
of melody, the taste of fruit, the
shape of a nose, or a list of
names.
• The storage capacity of STM is quite limited. Psychologist George Miller
referred to the STM capacity as seven plus or minus two.
• Rarely are people able to hold random bits of numbers of letters of more than
5-9 for very long.
• Short-Term Memory works as our working memory. Short term memory is used to
update memories that are used or updated. This is why you can’t remember the
phone number a friend just gave you a couple minutes ago. Thinking takes up
space in the STM and forces the numbers out. Writing out all of the items helps
people to remember.
• Humans are able to search the STM every time we are trying to recall
something.
• There are some ways to get around
the limited capacity in STM.
George Miller created something
called memory chunks.
• If you are able to group like words
together or like numbers, it
becomes easier to remember the
information.
• Social security numbers and bank
account numbers are broken up by
hyphens. This is because people
remember things in chunks.
• Long-Term Memory of LTM is the storehouse of
information that can be kept for long periods of
time.
• There are 4 ways that LTM differs from STM.
• 1) Information recall – LTM has to be indexed
when it comes to storing the information. We
retrieve information using cues. It can be a
question that can serve as a cue. Only the
information related to that cue surfaces.
• 2) Information in LTM is stored by meaning or
semantic codes.
• 3) Information in LTM tends to be permanent.
Not all psychologists agree that these memories
are permanent. So, if memory is lost in this case
it is not because we are forgetting it, but the
retrieval cues are not quite there.
• 4) Each stage of memory is largely handled by
a different part of the brain. STM is a function
of the frontal lobes whereas information in the
LTM is integrated in the hippocampus and then
transferred to the areas of the cerebral cortex
involved in language and perception for
permanent storage.
• It has been proposed that LTM has three
storage systems with different properties
and based on different brain mechanisms.
• 1) Procedural memory – for motor skills
and movements.
• 2) Semantic memory – memory for
meaning without reference to the time
and place of learning.
• 3) Episodic memory – memory for specific
experiences that can be defined in terms
of time and space. These seem to be the
hardest to recall.
• Some psychologists group semantic
memory and episodic memory together
under the heading declarative memory.
These two memory system are alike in
that they are easily described in words.
• LTM has unlimited capacity, but
information has to be categorized. This
helps the retrieval of these memories.
• Most people will categorically group
the new information.
• Those that put memorized words into a
story generally have a recall of 90%
versus those that do not.
• Many psychologists believe that
memories are linked together, through
experience.
• The spreading activation model states
that people create links between items.
E.g. a canary is a bird.
• Recall method – a measure of
memory based on the ability to
retrieve information from longterm memory with few cues.
• Recognition method – a measure
of memory based on the ability to
select correct information from
among the options provided.
• Relearning method – A measure of
memory based on the length of
time it takes to relearn forgotten
material. This shows that the
memory was never completely lost.
• This is when the person is able to
create some of the information
or recall something about the
thing the word referred to even
when they could not retrieve the
full idea. Sometimes, the word or
idea would pop into the mind of
the student, proving that they did
not lose it.
• Half of the ideas that we cannot
remember or are at the tip of
our tongues, can be remembered
within a minute.
• Sometimes, the order in which we
memorize something is as important as
the items on the list. When people are
asked to memorize items in a list exactly
as they appear, they can remember
words at the beginning and end, but
generally not in the middle. This is called
the serial position effect.
• The last items remembered tend to still
be in STM. The first items are learned
because they can be rehearsed enough
times where they transfer into LTM.
• When people are asked to recall the list
after 30 seconds, they tend to forget the
last words, too.
• Fergus Craik and Robert Lockhart proposed an alternative levels of
processing model that suggests the distinction between the short-term memory
and long-term memory is a matter of degree rather than separate stages.
• They believe there is only one storage beyond the sensory register. They think
the ability of the LTM depends upon how well the information is processed as
well as being coded for memory. The information will only be kept briefly if
the information is seen as shallow.
• They believe that if two groups are asked to process a set of words shallowly
and deeply with meaning, the participants that processed the information
deeply will remember it better.
• Why do we remember
some events from the
day and not others?
Does it have to do with
the value that we give
the memory?
• Some psychologists
believe that we process
memories that will aid in
our survival and
reproductive fitness.
• If the survival theory is correct, how
do humans develop the ability to
process other information that is not
pertinent to survival?
• Elaboration – the process of
creating associations between a
new memory and existing memories.
• Relating the information to yourself
will help you remember it. This will
help improve memory and
comprehension.
• Information stored for rote
memorization will not stay in the
LTM for a long time.
• What causes forgetting?
• There are four theories of
forgetting:
• 1) Decay Theory – memories
that are not used gradually
fade away after time. The
simple passage of time is a
cause of forgetting, both in the
sensory register and the STM. It
does not seem to affect LTM,
though.
• 2) Interference theory suggests that
forgetting takes place because other
information interferes with that
information.
• Similar memories might interfere with the
recollection of memories in LTM.
• Proactive interference – interference
created by memories from prior learning.
• Retroactive interference – interference
created by memories from later learning.
• Interference is viewed as the most
important cause of forgetting, but
appears to operate in different ways for
different kinds of memory.
• In STM, interference tends to overload this
capacity. New information can completely
knock other information out of STM.
• In 1932, Sir Frederic Bartlett came up with a
theory called reconstruction theory or schema
theory. This suggested that the information
stored in LTM is not forgotten, but is
sometimes recalled in a distorted, incorrect
manner.
• Schemas are associative networks consisting
of beliefs, knowledge, and expectations. Our
recollection in LTM becomes distorted
because we recall in many ways that are
consistent with our schemas.
• If you relay a story about someone, you will
tend to remember the negative over the
positive. You may even exaggerate the
details to explain away the positive aspects
that you heard about them.
• This theory is interesting to psychologists
because episodic memory is harder to
remember from LTM than is other memory.
We also will tend to give the general idea of
the story versus the details.
• False memory – remembering an
event that did not occur or that
occurred in a way that was
substantially different from the
memory of the event.
• Why do you think this is important
given a court of law?
• Children are less likely to have
false memories than adults, perhaps
because adults have more complex
association networks built up over
many years.
• Sometimes, human beings will distort
memories to make them more
consistent. Memory is guided by
schemas. Generally, these memories
are seen as facts and can be
destructive given certain situations.
• Motivated forgetting – forgetting that is
believed to be based on the upsetting or
threatening nature of the information that is
forgotten.
• Freud believed that the conscious mind
dealt with dangerous memories by pushing
it into the unconscious, by the act of
repression.
• What Freud didn’t consider is that
emotional arousal can actually improve
memories. When shown a list of emotional
words, these are easier to remember than
neutral words.
• Flashbulb memories of extremely emotional
events seem to be more vivid and accurate
to us, but can be less accurate than
memories from everyday events.
• There is some kind of change that takes
place in the nervous system when
something is learned.
• The engram – the partially understood
memory trace in the brain that is the
biological basis of memory. Karl
Lashley called this the biological basis
of memory.
• Hebb created an accurate model of the
biological processes responsible for
memory. He believed that each new
experience activated a unique pattern
of neurons in the brain. This activity
causes structural changes to occur in
those neurons near the synaptic gaps
that link them. He termed this synaptic
facilitation, which he believed was the
biological basis of memory.
• Eric Kandel won a Nobel Prize for
his research on the role of changes
in neural synapses in memory. He
did a study of memory on sea snails
as they have very simple nervous
systems composed of large neurons
that are easy to study.
• He did an experiment in which he
gave the snails shocks, which
changed the neurons at the point of
the synapses. The amount of the
neurotransmitter in the synapse
increased.
• This showed that Hebb was right in
that in some animals the learned
response was remembered in the
neurons at the synapse.
• Some studies suggest that chemical
changes in neurons at the synapses
that are at the basis for memory
are fragile at first, but if nothing
disrupts the process, they grow
more permanent over the course of
a few minutes or hours. This process
is called consolidation.
• In the chapter on sleep, there is
convincing evidence that a period
of sleep following learning helps
consolidate and protect new
memories. This is another reason
why overnight study sessions are not
efficient.
• Recently, it was realized that part
of the biological basis of memory
involves rapid changes in the
expression of genes that influence
neurons in the brain.
• A number of studies have shown
that some genes are turned off or
turned on when new memories
are formed.
• Experience can change how DNA
is expressed.
• There is evidence that
suggests physical
changes in neural
synapses involved in
the LTM, but not in the
STM.
• There is evidence that
different brain
structures are
involved in the three
stages of memory.
• Retrograde amnesia – a memory
disorder characterized by an inability
to retrieve old long-term memory,
generally for a specific period of time
extending back from the beginning of
the disorder.
• The only survivor in the Diana, Princess
of Wales, still cannot remember what
happened in the minutes before and
after the car accident. This can be
considered retrograde amnesia.
• The person is able to create new longterm memories after the incident. The
period of memory loss can stay for
minutes or days.
• Retrograde amnesia is caused by
seizures, brain damage, a blow to the
head, a highly stressful event, etc.
• Anterograde amnesia – disorder of memory
characterized by an inability to store and/or
retrieve new information in long-term
memory.
• H.M. is an example of an individual with this
condition. He had terrible seizures and his
surgeon decided to perform brain surgery in
which he injured the memory portion of the
brain. He could not remember anything after
the surgery. He could remember anything
before it, but not after.
• H.M. could retain information for about 15
seconds due to an intact STM and could
remember it longer if he was allowed to
rehearse it.
• H.M. could not store new memories of current
events, could read the same magazine over
and over, and could not remember his father’s
death that occurred after his surgery.
• His new social friends could not be
remembered, but he could recall old stories
about his friends before the surgery. He was
essentially incapable of forming new
friendships with people as he would not
remember them if he’d not met them before
the surgery.
• Persons with this damage have very
little trouble with procedural memories,
but have trouble with episodic
memories. H.M.’s hippocampus was
damaged during surgery, which plays
a role in episodic memory, but not
procedural memory.
• Both anterograde and retrograde
amnesia are experienced by
individuals with Korsakoff’s Syndrome
– a brain disorder caused by
prolonged loss of the vitamin thiamine
from the diet of chronic alcoholics. They
will generally partake in confabulation
– when they don’t remember something
they make it up.