3. Forgetting - gleneaglesyear12psychology

Um I forget…..
Forgetting – refers to the inability to retrieve
previously stored information.
The information may still be stored in your memory
but you are unable to retrieve it when you want to for
some reason.
If you didn’t forget, your mind would be too cluttered
with so much info. you would have difficulty retrieving
and selecting the information you need.
Remembering might take hours rather than seconds!
Forgetting has an adaptive purpose and contributes
to our survival and our sanity.
The Forgetting Curve
German psychologist, Hermann
Ebbinghaus was the first person to
scientifically study forgetting in the late
Ebbinghaus sought to measure the
amount of information retained and the
rate at which information is forgotten.
Ebbinghaus’ research
Ebbinghaus learned a series of lists of 13
three-letter nonsense syllables (e.g. qel,
nuz) until he could recite them all without
error on 2 successive occasions.
Used nonsense syllables as they are all
equally difficult to learn and don’t have a
specific meaning or personal associations
like words where his past experience of the
information being learned may influence
Ebbinghaus’ research
Ebbinghaus tested his recall of each list
after a specific period of time had
elapsed from the initial learning. The
delay period ranged from 20 minutes to
31 days.
Ebbinghaus was then able to measure
the amount (quantity) and rate (speed)
of forgetting.
Ebbinghaus’ research results
20 minutes
 1 hour
 1 day
 1 week
58% recalled
44% recalled
34% recalled
21% recalled
The graph that demonstrates
Ebbinghaus’ findings is known as the
forgetting curve.
The forgetting curve
The Forgetting Curve
The forgetting curve shows the pattern (rate
and amount) of forgetting that occurs over
Forgetting is rapid soon after original learning
and then rate of memory loss gradually
declines followed by stability in the memories
that remain.
More than half memory loss occurs in the first
hour after learning.
Almost all material that will be forgotten is lost
in the first eight hours (about 65%).
Other “forgetting” research
Since Ebbinghaus, other research using different kinds of
learned information has found results that consistently
indicate a characteristic pattern of forgetting demonstrated
by the forgetting curve.
New skill similar to flying plane (Fleishman & Parker, 1962)
New language (Bahrick, 1984)
Cardio-pulmonary resuscitation (McKenna & Glendon, 1985)
Psychology subject (Conway, Cohen & Stanhope, 1991)
Lengthier learning period
When initial learning takes place over
more extended periods of time, (e.g.
weeks or months) more information is
retained, but the rate at which
information is lost remains the same.
See graph on following slide.
The forgetting curve
Influences on forgetting
The pattern of forgetting outlined by the forgetting curve is applicable to
a wide variety of materials under many conditions.
However, the more meaningful the material, the slower the rate of
How well the information is initially encoded influences the amount and
rate of forgetting. The better the initial learning, the longer it is likely to
be retained.
When material is well learned, the rate of retention is about the same
whether the material is difficult or not and whatever the learning ability of
the individual.
Slow learners and fast learners both forget at about the same rate.
Easily learned material does not appear to be retained longer than more
difficult material.
Measures of retention – measuring
Research findings suggest that the
amount of information that will be
retrieved from memory depends, at least
partly, on the type of retrieval question
Three kinds of measures are used to
determine how much information has
been retained: recall, recognition and
Measures of Retention – Measuring Memory
Recall - Being asked to reproduce information with the
fewest possible cues to assist retrieval.
e.g. Required to learn a list of randomly selected words.
Free Recall – when participants are simply asked to
remember as much information as possible in no particular
order –e.g. List of grocery items
Serial Recall – asked to recall information in a particular
order Names of Cities (itinerary)
During recall a general cue is used to retrieve information
associated with the cue, by searching through LTM storage
system to find something that matches the cue (Best, 1999).
However, often the general cue doesn’t provide enough of a
hint to enable location of the relevant information because the
list of possible matches is quite large.
Therefore, the more specific the cue, the more likely location
and retrieval of the relevant information from LTM.
Cued Recall - makes use of more
specific cues to aid retrieval. Given a
cue then asked to recall
e.g. Seven Dwarfs: first letter of
B, G, S, D, D, H, S
Measures of Retention – Measuring Memory
Identifying correct information from among
alternatives. Can retrieve more this way as
recognition provides more cues for retrieving from
Example – multiple choice Q’s
Recognition is more sensitive measure of memory
than recall for testing information stored in LTM.
Uni students asked to recall seven dwarfs – mean of
69% of the names. When given a list of alternatives
from which to select the seven names, the accuracy
rate increased to a mean of 86% (Meyer &
Hilterbrand, 1984).
Generally, irrespective of the kind of
information, people can typically recognise
more than they can recall.
In recall we ask: “What is the item?”
 In recognition we ask “Is this the item?”
Incorrect alternative answers (“distractors”)
on multiple choice questions are extremely
similar to the correct answers.
Measures of Retention – Measuring Memory
Even if can’t recall or recognize doesn’t mean there
is no memory.
Relearning or the “method of savings” involves
learning information again that has been previously
learned and stored in LTM.
If information is learned more quickly the second
time, it is assumed that there must be some
information retained (or “saved”) from the first
learning experience, whether the person realises it or
Relearning is considered the most sensitive measure
of retention.
By “re-studying” a weak association regains its
original strength in memory. It’s as if the
previous experience has prepared us for
remembering the material better when we
encounter it again.
Ebbinghaus (1885) was the first researcher to
scientifically study relearning. He found that
even if he couldn’t remember a single word
from the original list, he could relearn the list of
nonsense syllables much more quickly a
second time than the time he took to initially
learn the list. He assumed therefore, that
some information had been retained from the
initial learning.
Savings Score
If initial learning took 10 trials to remember list and
then six months later it only took 5 trials to relearn
the list the savings would be 50%.
Savings =
(no. of trials for original learning) – (no. of trials for relearning
(no. of trials for original learning)
Savings score
Savings scores can also be calculated
on the basis of the time taken to relearn
Measures of retention - sensitivity
The sensitivity of a measure of retention
refers to its ability to assess the amount of
information that has been stored in memory.
Recall worst
Recognition better
Relearning best (i.e. More likely to detect
information that has been learned and stored
in memory at some point in the past).
Research on sensitivity of 3
measures of retention
Nelson (1978) used 24 uni students.
 3 stages of experiment
 1. Initial learning stage
 2. Stage in which recall and recognition
were tested.
 3. A relearning stage
Students were not told of the second and third
stages of the experiment at the beginning.
Research on sensitivity
1st. Stage – given a series of 20 number-word pairs to learn
(e.g. 48-party, 95-horse) – these are called “paired
2nd. Stage – 4 weeks later – participants required to participate
in testing and relearning stages.
Testing – complete 2 different types of tests of memory – a test
of recall (given 48 and then asked for the word) and then a test
of recognition (given 48 then 20 possible words to pick the
correct word of the pair).
Then participants given a distraction task for 10 minutes.
3rd. Stage – relearning ten of previously learned paired associates
that were incorrectly recalled earlier as well as ten new paired
Then given a test of recall and debriefed before leaving.
Research results on sensitivity
Mean of 48% of target words correctly recalled
Mean of 69% of target words correctly
recognised (2nd. Stage)
Target words correctly recalled after relearning
was 88% for old items and much higher than
for the new items.
These results were found to be statistically
significant at p<0.001 (an acceptable
difference) – due to the types of measure of
retention used rather than due to chance
See Table 7.1 on p. 369
Theories of Forgetting
Psychologists have developed a number of theories to
explain why we forget.
1. The right retrieval cue or prompt is not used
2. There is interference from competing material
3. There is some underlying motivation not to
4. Memory fades through disuse over time.
No single theory alone is able to explain all instances of
The inability to retrieve previously stored information. If
you forget that doesn’t mean that the information is gone
forever, it simply means that for whatever reason you
have failed to retrieve that information.
Theories of forgetting
Retrieval Failure Theory: Forget because fail to use the right
retrieval cue.
A retrieval cue is any stimulus that assists the process of
locating and recovering information stored in memory.
A retrieval cue acts as a prompt or a hint that guides the search
and recovery process within memory.
Being asked a question is an example of a cue. It focuses your
search for information in LTM in specific areas.
Other cues are less direct and might not be recognised as
memory prompts. E.g. smell of a particular perfume, a
photograph, the look of someone’s face.
The theory is often referred to as “cue-dependent forgetting”.
Theories of forgetting
Tip of the tongue (TOT) phenomenon: is a state or
“feeling” that occurs when you are aware of knowing
something, and confident you will eventually
remember it, but you are not able to retrieve it from
memory at that point in time.
When information is eventually recalled it usually
occurs suddenly like it “pops” out of memory, often
when not consciously thinking about it.
We seem to have some information about the word
being searched for (e.g. beginning letter or how
many syllables or what it rhymes with).
We can often confidently eliminate words that are
incorrect based on improper sound or length.
Tip of the Tongue phenomenon
Possibly due to partial retrieval
process where bits of information can
act as retrieval cues for the required
Lack of correct cue.
Tip of the Tongue phenomenon
Provides evidence that information in LTM is stored in an
organised way and in a variety of forms.
Illustrates that retrieving is not an “all or nothing
process” as we can remember parts of what we want to
Information is stored in LTM but is not accessible without
the right retrieval cue.
As information is stored in LTM in a variety of forms, a
certain type of cue is required for a certain type of
TOT experiences indicate that information stored in LTM
is organised and connected in relatively logical ways. In
the struggle for retrieval, logically connected bits of
information are frequently triggered which can act as
additional cues, helping us to find the memory.
Interference theory
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.
The more similar the information, the more likely it is that
interference will occur.
If learning the similar information occurs close in time,
interference is more likely.
Two main kinds of interference:
Retroactive interference – New information interferes with the
remembering of old information
Proactive interference - Old information interferes with ability
to remember new information
Motivated forgetting
Motivated forgetting describes forgetting
that arises from a strong motive or desire
to forget, usually because the experience is
too disturbing or upsetting to remember.
Defense mechanism that protects us from
distressing memories.
Two types of motivated forgetting:
Repression - unconsciously blocking a memory of an event or
experiences from entering conscious awareness.
Based on Freud’s theories that a memory is too psychologically
painful or unpleasant to remember the specific information.
According to Freud, repression is a form of self-protection or
self-defence (called a defence mechanism) from the anxiety or
distress associated with the experience.
Information is not lost from memory but is not easily accessible
during normal waking consciousness.
Repressed information can signal it’s existence in dreams, or
when a person pauses, fumbles for words, or blushes when
certain topics are raised.
Freud believed a repressed memory can be retrieved when
some of the unpleasant emotion associated with the related
experience is “diffused” (lessened).
Suppression – involves being motivated to forget an event or
experience by making a deliberate conscious effort to keep it
out of conscious awareness. The person is aware of the
event/experience but consciously chooses not to think about it.
Research using brain imaging techniques now suggests
suppression may be possible.
 Using fMRI images of people actively trying to forget a list of
words learned showed a higher level of activation in the left and
right frontal cortical lobes (brain areas apparently involved in
suppression of memories) which resulted in reduced activation
of the hippocampus (brain area involved in recalling
Motivation can change the tone and content of memories that
we do retrieve. Research found that motivation can also lead
us to recode distressing memories as more pleasant by
selectively reworking memories as neutral or even pleasant.
Remembering not what actually was, but rather the way we
would have liked them to have been.
Repression and Suppression
Many psychologists accept that memory
can be affected by an individual’s
conscious or unconscious needs fears,
anxieties and desires.
Read case study on motivated forgetting
in Box 7.3 on page 382.
Infantile amnesia
Usually our earliest memories are for events
occurring between 3 and 5 years old.
Sometimes as early as age 2 for significant
events such as sibling birth or a
Recollections by adults of memories from age
1 are usually memory reconstructions. (Loftus,
Infantile amnesia is the loss of memory for
our experiences during infancy.
Explanations of infantile amnesia
Freud’s explanation for infantile amnesia is because the
infant’s sexual impulses and fantasies are too
psychologically threatening to be consciously
remembered. Problem with this is that ALL memories are
amnesic not just the threatening or disturbing ones.
Another explanation is lack of language development
which prevents a child from encoding the experiences into
Another explanation involves brain development. The
hippocampus does not mature until 2 years of age. Thus
it is unable to encode and store events and other
experiences in LTM prior to this time. Other late maturing
brain structures such as the cerebral cortex may also play
a role in formation and/or storage of memories.
Decay theory
Decay Theory is based on the assumption that when
something new is learned, a physical or chemical
memory trace, (sometimes called an engram)
containing stored information is formed in the brain as
the information is consolidated in LTM.
Decay Theory proposes that forgetting occurs because a
memory (or the memory trace fades through disuse as
time passes, unless it is reactivated by being used
e.g. like gradual fading of a photograph
Earliest theory of forgetting.
Explains forgetting in physiological terms.
Probably the most commonly believed in the wider
Decay theory
One research study, a pattern of rapid then more
gradual deactivation of neural pathways in the
hippocampus (part of the brain involved in
consolidation of memory) was observed.
It also appears that the mere passage of time (but
not time alone) may also contribute to forgetting both
in sensory memory and STM, but not in LTM.
Many people have vivid memories of things they
have not thought about for years.
Most people can, in time, also recall material that
was apparently “lost”. E.g. Name of an old friend
you bump into in the street.
Decay theory
If memory trace simply decayed over time, then the
presentation of retrieval cues would have no effect
on the retrieval of information or events that have
been held in LTM for a considerable period of time,
but it does.
Thus other factors such as interference or
inappropriate retrieval cues make memories difficult
to retrieve, not simply because of fading memory
traces over time.
Read Box 7.5 comparing theories of forgetting (page
Read Box 7.6 on Pseudoforgetting: encoding failure
(page 385)

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