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FORGETTING
???
FORGETTING

Forgetting refers to the inability to retrieve
previously stored information.

When you forget something it means that it is
unavailable to you at the time you are trying to
remember it.

The information may be stored in your memory, but
for some reason you are unable to retrieve it.

Although forgetting results in the loss of information
and many skills, if you did not forget, your mind
would be cluttered with so much information that you
would have great difficulty retrieving and selecting
the information that you needed.

Like remembering forgetting has an adaptive
purpose and contributes to our survival and our
sanity.
THE FORGETTING CURVE

Hermann Ebbinghaus was a German psychologist
who was the first to scientifically study forgetting in
the late 1800’s.

To measure the amount of information retained and
the rate at which information is forgotten,
Ebbinghaus conducted an experiment using himself
as the only participant.

The experiment involved him learning a series of
lists of nonsense syllables, until he could recite them
without error on two separate occasions.

Ebbinghaus tested his recall for each list after a
specific period of time had elapsed from the initial
learning.

He first learned one list, then tested his recall after a
specific delay period. Then he learned another list,
tested his recall after another delay period, and so
on.

The delay ranged from 20 minutes to 31 days.

Ebbinghaus was then able to measure the amount
and rate of forgetting.

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FINDINGS:
20 minutes after initial learning he could remember
58% of nonsense syllables.
One hour after learning his retention was 44%.
A day later he could recall 34%.
A week later his recall had fallen to around 21%.

This data, once plotted on a graph became known
as the forgetting curve.

The forgetting curve shows the pattern of
forgetting that occurs over time.
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
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Generally the graph shows that forgetting is rapid
soon after the original learning, then the rate of
memory loss gradually declines, followed by stability
in the memories that remain.
More than half of the memory loss occurs in the first
hour of learning.
Virtually all the information that will be forgotten is
lost in the first eight hours.

This pattern of forgetting tends to occur for a range
of materials under many conditions.

The more meaningful the material, the slower the
rate of forgetting.

The amount and rate are also influenced by how
well the information was initially encoded- the better
the initial learning, the longer the material is likely to
be retained.
THEORIES OF
FORGETTING
Psychologists have developed a number of
theories to explain why we forget.
Forgetting may occur because:
1. The right retrieval cue is not used
2. There is interference from competing
material
3. Memory fades through disuse over time
RETRIEVAL FAILURE THEORY

If you have ever experienced a ‘mental blank’ in an
exam or in a job interview, only to recall the exact
information at a later point in time, you have
experienced retrieval failure.

Most of the time we can retrieve information from
LTM with relative ease.

This is because most of the time you are able to
retrieve information from the various storage
systems in your LTM using a retrieval cue to locate
the relevant information.

A retrieval cue is any stimulus that assists the
process of locating and recovering information
stored in memory.

It is a prompt or cue to guide the search and
recovery process within memory.

According to retrieval failure theory we sometimes
forget because we lack or fail to use the right cues
to retrieve information stored in memory.

This explanation of forgetting suggests that
memories stored in LTM are not actually forgotten,
but are temporarily inaccessible.

One of the most frequent experiences of retrieval
failure is the tip-of-the-tongue phenomenon (TOT).

This is the feeling of being aware of knowing
something, being confident that you will remember it
at any moment, but not being able to retrieve the
information at that point in time.
INTERFERENCE THEORY

Sometimes memories can interfere with each other.
This is called interference.

Interference theory proposes that forgetting in LTM
occurs because other memories interfere with the
retrieval of what we are trying to recall, particularly if
the other memories are similar.

If learning of similar material occurs close in time,
interference is more likely.

There are two types of interference:
1.
Retroactive interference
2.
Proactive interference
RETROACTIVE INTERFERENCE

When new information interferes with the ability to
remember old information, psychologists refer to the
interference as retroactive interference.

Eg. You are at a party and you are introduced to a
guy named John. Not long after you are introduced
to Jim. After a while you bump into John again but
accidentally call him Jim.

With retroactive interference, new learning interferes
with the retrieval of previously learned material.
PROACTIVE INTERFERENCE

Interference also works in the opposite direction.

Information learned previously can interfere with our
ability to remember new information. This effect is
called proactive interference.

According to interference theory, interference
primarily comes from memories of similar
information.
MOTIVATED FORGETTING

Motivated forgetting refers to the inability to
retrieve information because the individual derives
some benefit from not remembering.

Sigmund Freud was one of the first to consider the
idea of motivated forgetting, which he called
repression.

He claimed that it was an unconscious, unintentional
process through which the individual may avoid
feelings of anxiety about traumatic events.
An important feature of repressed memories is that
although they may not be readily accessible to
conscious recollection, they may still be retained.
Eg. Hypnosis
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Memories that are retrieved from the unconscious
are called recovered memories.

Not all motivated forgetting is unconscious- an
individual may quite intentionally and consciously
want to forget something.

This is called suppression.
DECAY THEORY

Some psychologists suggest that forgetting is a
process of decay.

Memories that are formed and not used begin to
fade, become weaker with time, and eventually
decay to the point where they can no longer be
recollected- that is, they are forgotten.

This theory, known as decay theory, was first
proposed by Edward Thorndike in 1914.

The decay of memory over time may be the result of
deterioration in the connections between the
neurons that combine to make up a memory trace.

Decay theory suggests that memories that are not
retrieved or rehearsed dissipate over time as the
synaptic connections between neurons that
constitute the memory trace begin to degrade.
ORGANIC CAUSES OF
FORGETTING

Organic causes of forgetting are due to damage
to the brain, such as:
-
a head injury
disease
severe malnutrition
stroke
necessary brain surgery
long-term alcoholism.
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Any loss of memory is referred to as amnesia.

Amnesia is often an indicator of brain damage, and
may help to define the nature and extent of the
damage.
AMNESIA

Various types of amnesia have been defined,
relating to the time at which the event that resulted
in the brain damage took place.

It is easier to establish the exact time of brain injury
in cases of head injury or stroke than when amnesia
results from progressive forms of brain damage
caused by alcohol or Alzheimer’s disease.

There are two main types of amnesia:
Anterograde amnesia
Retrograde amnesia
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ANTEROGRADE AMNESIA
 A brain
injury patient who suffers memory
loss for events that occur after the brain is
damaged has anterograde amnesia.
 Patients
can usually remember and talk
about events that occurred prior to their
brain injury, but cannot remember
information about what has happened since
the event.
 The
structure in the brain called the
hippocampus, located under the
temporal lobes, is critical to the ability
to form new memories.
 Damage
to this structure is thought to
result in severe anterograde amnesia.

The information processing model of memory offers
one explanation for anterograde amnesia.

According to this model, for information to be
permanently implanted in memory it must pass
through the three stages of mental processingsensory memory, STM and LTM.

For people who experience anterograde amnesia,
information enters sensory memory, is attended to
and transferred to STM. It can be manipulated in
STM and rehearsed indefinitely, but no permanent
memories can be formed.
RETROGRADE AMNESIA

An inability to remember information that was
acquired before brain damage is called retrograde
amnesia. (Retro refers to backward, and refers to
memory loss that goes back in time).
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The extent of retrograde amnesia varies greatly,
ranging from moments to days, weeks or even
years.

The amount of time over which memories are
affected is often related to the severity of the
damage to the brain.

In most cases resulting from a brain injury, there is
some recovery of the lost memories- usually with
memory for older events recovering first.
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However, there always seems to be a period –
usually just prior to the time when the brain injury
occurred- for which there is no recovery of memory,
and the amnesia is absolute.

In cases that are as a result of other damage to the
brain, such as Alzheimer’s disease, the extent of the
amnesia is often not clearly defined and the
recovery of the lost memories is rare.

The information processing model of memory
explains retrograde amnesia in terms of an
interruption to the consolidation of the memory
trace.

In the period of time just prior to the brain trauma, a
memory trace was forming as information was being
processed from STM to LTM.

At the point of the trauma, the consolidation process
was interrupted and therefore the memory of
information just prior to the injury will not be
consolidated and therefore lost forever.
MEMORY DECLINE OVER THE
LIFESPAN

Most people believe that memory decline is a
natural part of ageing.

Research shows however, that although there is
some natural decline in memory with age, memory
is not an inevitable consequence of ageing.

If a decline in memory is experienced through
ageing, effects are more likely to be experienced in
working memory and the declarative memory
systems (episodic and semantic memories) than in
procedural memories.
EFFECTS OF AGEING ON STM

The impact of age on STM seems to depend on the
nature of the task.

If the task is simple it should not be affected by age.

If the task is more complex, age related factors may
impact on effective STM functioning.

Neuroimaging studies have shown that beyond 60
years of age, there is a decrease in the activation of
areas of the frontal lobes of the brain believed to be
involved in STM.
EFFECTS OF AGEING ON LTM

Research findings indicate that some LTM stores
are more likely to be affected by age than others.
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Episodic memory is the most likely to decline with
age and this decline can start as early as 30 or as
late as 50.

Although many semantic and procedural memories
are not easily lost, older people take longer to learn
new information and skills.

It seems that older people do not encode new
information with as much detail or as precisely as
young people.

The speed and fluency of retrieval of information
from semantic memory is particularly prone to
decline.

One explanation for this is lack of motivation.

There is however less age-related decline for
memory tasks in which a person is motivated to
remember something. Eg. Taking a cake out of the
oven.

A second explanation is that as people get older
they tend to lose confidence in their memory.

A third explanation is that the inability of some older
people to access information from LTM may be
more to do with the kind of measure of retention
used that with their age.
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The most common reason is a process called
cognitive slowing. This refers to the slowing of
Central Nervous System functioning and the inability
to effectively process information the way a person
may once have.

This occurs because the frontal lobe shrinks as age
progresses and therefore cognitive function is
influenced by this process.
ENHANCING MEMORY

We can rely on specific mental strategies if we want
to improve our memory.

Sometimes we are able to remember information
simply because it stands out or is unusual.
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Other information requires conscious effort in order
for it to be remembered.

To ensure that information goes beyond sensory
memory we must pay attention to it. It must also be
organised and integrated into LTM with information
already in LTM.
QUALITY OF ENCODING

An effective way of enhancing retrieval is to ensure
that the information is properly encoded in LTM and
integrated into information already stored in LTM.
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This can be done through elaboration.
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Elaboration describes the way in which new
information is made more meaningful by linking it to
known information already stored in LTM.

The more extensively information is elaborated
(through elaborative rehearsal), the deeper the level
of processing of that information, the more likely it is
to be remembered.
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Self-referencing is another effective way to improve
memory by elaborating information.

Self-referencing involves relating new information to
personal experiences or your personal situation in
some way.

One reason that elaboration produces effective
memory is that it adds to the distinctiveness of the
‘codes’ used for LTM.
CONTEXT- AND STATEDEPENDENT CUES
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Another effective way of enhancing retrieval from
LTM is to re-create the conditions under which the
required information was originally learned.
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This approach is based on the encoding specificity
principle.
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This principle involves a general ‘rule’ that the more
closely the retrieval cues match the original learning
conditions, the more likely it is that the information
will be recalled.
CONTEXT-DEPENDENT CUES

Why is it that police investigating a crime may take
an eyewitness back to the crime scene, particularly
if the witness is having some trouble recalling some
of the details of what they saw which are critical to
the investigation?

The answer is based on research findings that cues
in the environment may be important in helping to
locate and retrieve related memories.

Context-dependent cues are environmental cues
in the specific context (setting) where a memory was
formed, which act as retrieval cues to help access
the memories formed in that context.
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These cues may include the sights, sounds and
smells within the specific situation.

The context dependency of certain memories helps
explain why an eyewitness may recall apparently
forgotten information about a crime when they return
to the scene of the crime.
STATE-DEPENDENT CUES
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State-dependent cues are associated with an
individual’s internal physiological and/or psychological
state at the time the memory was formed, which act as
retrieval cues to help access those memories.
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It seems that taking a drug can produce an internal state
with unique psychological and physiological
characteristics, aspects of which may become encoded
with new memories.
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At a later point, the same internal state can provide
additional retrieval cues that assist recovery of
information from memory.
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Your mood also provides state-dependent cues.
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We seem to associate good or bad events with their
accompanying emotional state.

This means that our emotional state becomes a
retrieval cue when we feel good or bad again, and
they trigger memories that are consistent with the
mood.

However, when we are happy, happy events are
recalled; but when we feel down, our minds can
become flood with sad or negative events of the
past which in turn darken our interpretations of
current events.
MNEMONIC DEVICES
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Techniques for enhancing or improving memory are
known as mnemonic devices.
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A mnemonic device is any internal strategy or
method that makes it easier to encode, store or
retrieve information.
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Mnemonic devices may be visual or verbal, and they
generally impose some sort of organisation on the
material to be remembered.
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Mnemonic strategies are always entirely internal.
Memory aids such as writing a shopping list are not
mnemonic strategies because they rely on external
items (in this case a pen and paper).
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Narrative chaining
Method of loci
Peg word method
Acronyms, acrostics and rhyming
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NARRATIVE CHAINING
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The link method is a mnemonic device that
involves linking each item in a list with the previous
item, so that the items form a mental chain of
images.
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Recalling the items involves visiting each of the links
in the chain.
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Narrative chaining involves linking the items
through the development of a story, or narrative,
rather than a series of images.
METHOD OF LOCI
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The method of loci is a mnemonic that relies on the
use of a well-learned pathway with distinct locations
that can be associated with the items to be
remembered.
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To use the method of loci, you need to recall a
sequence of distinct locations and associate them
with each word to be remembered.
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Imagine yourself walking through a house and
associate each word on a list with an item in each
room.
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When you need to recall a list of words, imagine
yourself revisiting the house and walking through
the same rooms-this will probably cause you to
remember the word you associated with each
location.

Experimental investigation of the method of loci has
found that participants more than doubled the
number of words they were able to recall when
using the method of loci, compared to when relying
on free recall.