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Explanations Of Forgetting!
- Trace Decay: Information that enters the STM leaves
a trace in the brain due to the excitation of nerve
cells. This neural activity gradually dies away unless
the material is rehearsed.
- Hebb (1949) - Argued that whilst
learning is taking place, the engram
which will eventually be formed is very
delicate and liable to disruption because
it is an active trace. With learning, it
grows stronger until a permanent engram
is formed.
- Some researchers
argue that if
knowledge and
skills (in LTM) are
not used and
practised, then the
engram will decay.
- Research Study: Waugh And Norman (1965) Aim: To
investigate STM using a serial probe technique and
support trace decay as a theory. Method: A repeated
measures design, was conducted where participants
were presented with lists of 16 digits at a rate of one to
four per second. The last digit, known as the probe,
occurred once before in the list and the task was to
recall the digit which had followed it. It was predicted
that participants would recall the digit more accurately
if they were presented rapidly (four per second) as
there would be less time for the trace to decay, than if
they were presented more slowly (one digit per second)
Results: There was no relationship between speed of
presentation and recall, which suggested trace decay
was not a major source of forgetting on this task.
Conclusion: Waugh and Norman concluded that
forgetting is probably better explained by interference
rather than decay.
- Evaluation: Lacks ecological
validity as the tasks set were
artificial and therefore may not
be relevant to everyday life.
- Evaluation of Trace Decay: - Difficult to test trace decay theory because if participants are
tested after different time periods they could be rehearsing. Therefore strengthening the
trace. Forgetting could be due to interference from the task rather than decay of the
memory trace, - Trace decay theory has difficulty dealing with situations where items
which cannot be remembered at one time can be remembered at a future time, even
though no additional presentations have been made. - Experiment by Peterson and
Peterson is used as evidence for the role of decay in STM, as their findings show that after
18 seconds the trace has almost completely decayed when rehearsal is prevented. -
Waugh and Norman who set out to support trace decay, concluded that interference is the
most likely cause of forgetting in STM.
- Evaluation of Trace Decay: - Difficult to test trace decay theory because if participants are
tested after different time periods they could be rehearsing. Therefore strengthening the
trace. Forgetting could be due to interference from the task rather than decay of the
memory trace, - Trace decay theory has difficulty dealing with situations where items
which cannot be remembered at one time can be remembered at a future time, even
though no additional presentations have been made. - Experiment by Peterson and
Peterson is used as evidence for the role of decay in STM, as their findings show that after
18 seconds the trace has almost completely decayed when rehearsal is prevented. -
Waugh and Norman who set out to support trace decay, concluded that interference is the
most likely cause of forgetting in STM.
- Evaluation: Lacks ecological
validity as the tasks set were
artificial and therefore may not
be relevant to everyday life.
- Hebb (1949) - Argued that whilst
learning is taking place, the engram
which will eventually be formed is very
delicate and liable to disruption because
it is an active trace. With learning, it
grows stronger until a permanent engram
is formed.
- DISPLACEMENT THEORY: Explains forgetting from the STM in terms of the limited
capacity of this store. It suggests that there are a limited number of 'SLOTS' for information
in STM (approx. 7 suggested by Miller) and when the system is 'FULL' the oldest material is
'PUBLISHED OUT' or displaced by incoming information.
- The study by Waugh and Norman, using their serial probe task, offers support
for the displacement theory of forgetting. They found that if the probe was one
of the digits at the beginning of the list, recall was small because later digits
would have displayed earlier ones. However, if the probe was presented
towards the end of the list, recall was high, since the last digits would still be
available in short term memory. the poorer recall of items in the middle of the
serial position curve could also be attributed to displacement.
- Evaluation of Displacement: ~ Displacement theory seems to give an adequate
account of forgetting from STM when applied to the multi store model of memory.
Empirical evidence, such as Murdock's primary/recency experimental findings,
offers support for the displacement theory. However, more recent models of
memory, such as the working memory model, have indicated that STM is much
more complex than the unitary, limited capacity short- term store first proposed
by Atkinson and Shiffrin's multi-store model of memory.
- Evaluation of Displacement: ~ Displacement theory seems to give an adequate
account of forgetting from STM when applied to the multi store model of memory.
Empirical evidence, such as Murdock's primary/recency experimental findings,
offers support for the displacement theory. However, more recent models of
memory, such as the working memory model, have indicated that STM is much
more complex than the unitary, limited capacity short- term store first proposed
by Atkinson and Shiffrin's multi-store model of memory.
- The study by Waugh and Norman, using their serial probe task, offers support
for the displacement theory of forgetting. They found that if the probe was one
of the digits at the beginning of the list, recall was small because later digits
would have displayed earlier ones. However, if the probe was presented
towards the end of the list, recall was high, since the last digits would still be
available in short term memory. the poorer recall of items in the middle of the
serial position curve could also be attributed to displacement.
- Interference Theory: ~ Is
concerned with what occurs
before, during and after learning.
At the beginning of the storage
process, interference can prevent
new information from passing
from STM to LTM. In LTM, as the
store of information grows, there
will be increasing interference
between competing memories.
- There are Two types of
Interference: ~ Proactive
interference, where earlier learning
interferes with what you are trying
to learn at present. E.G. you have
learnt Spanish and are now having
difficulty learning French. ~
Retroactive interference, where
more recent learning interferes with
the recall of earlier material. E.G.
you know your present mobile
number but cannot now remember
your previous one.
- Research Study: Keppel and Underwood (1962) Aim: To
investigate the effects of proactive interference on recall from
memory. Method: In a repeated measures design, participants
were given a series of trails where they had to learn trigrams
(for example TXK) and then count backwards for 3,9 or 18
seconds (the independent variable). The order of testing was
balanced to control for order effects. The dependent variable
was the recall of the trigram. Results: On the first trail,
performance was almost 100 per cent even though some
participants had only 3 second intervals whilst others had 18
seconds. On the second and third trials, performance falls
steadily as the interval increases. If decay is the sole
explantation for forgetting, performance should fall as the
interval increases on the first trail as well as subsequent trails.
Conclusion: The inferior performance on later trails was due to
interference, the first trigram learned is remembered perfectly.
- There is no
preceding item to
interfere. This type
of interference is
proactive because
earlier learning of
trigrams interferes
with later learning.
Evaluation: This
study has low
ecological validity as
this situation would
not arise in real life.
- Evaluation of Interference Theory: ~ The strongest support for
interference theory comes from lab studies such as the Keppel
and Underwood study. However, such lab studies tend to use
nonsense syllables as the stimulus material. When meaningful
material is used, interference theory suffers as a general theory of
forgetting because the situations it best deals with are rarely
encountered in everyday life. Studies such as Baddeleys lack
ecological validity.
- There is no
preceding item to
interfere. This type
of interference is
proactive because
earlier learning of
trigrams interferes
with later learning.
Evaluation: This
study has low
ecological validity as
this situation would
not arise in real life.
- There are Two types of
Interference: ~ Proactive
interference, where earlier learning
interferes with what you are trying
to learn at present. E.G. you have
learnt Spanish and are now having
difficulty learning French. ~
Retroactive interference, where
more recent learning interferes with
the recall of earlier material. E.G.
you know your present mobile
number but cannot now remember
your previous one.
- Lack Of Consolidation: ~ Time-dependent changes occur in the nervous system as a result of learning. In
order for information In STM to become an LTM, it must go through a process known as consolidation. During
consolidation, STM is repeatedly activated. If something interrupts the process, say a bang to the head, then
STM cannot be consolidated and memories cannot be 'STORED' for long-term access.
- Research Study: Yarnell And Lynch (1970) Aim: ~ To investigate memory loss due to
concussion. Method: ~ A field study was carried out with American footballers who
were concussed for a brief period of time during a game. They were approached
immediately as they regained consciousness and asked for details of the events that
occurred in the game just prior to the injury. They were asked again 20 minutes later.
Results: ~ Accurate information was given when the footballers were questioned
immediately after they regained consciousness, but the same information was not
available 20 minutes later. Conclusion: ~ The consolidation process had been
disrupted and therefore the information about the game was not available in
long-term store. Evaluation: ~ Field study, high in ecological validity. Problems
occurred with control however. Ethical implications when questioning patients when
they had only just become conscious.
- Evaluation Of Lack of Consolidation: ~ Patients who have been concussed often suffer
retrograde amnesia, which is a loss of memory for events prior to the concussion. This may
be because the consolidation process has been interrupted. ~ Electro- convulsion therapy
(ECT) causes memory loss for events just before the therapy is given. Evidence suggests
that after a one-hour delay between learning and ECT, perfect retention occurs. This
suggests that the essential consolidation period required, to ensure information reaches
long-term store., is up to one hour. There is evidence from both animals and humans to
support the theory that a consolidation process is necessary to prevent memory disruption
and loss.
- Retrieval Failure: ~ According to retrieval failure theory, memories cannot be recalled
because the correct retrieval cues are not being used. The role of retrieval cues is
demonstrated by the 'TIP OF THE TOUNGE' phenomenon, in which we know that we
know something but cannot retrieve it from LTM at that particular time. Tulving ~
Investigated retrieval failure in LTM. He gave participants a list of words and then
asked them to write down as many as they could remember in any order. Later
participants were asked to recall them a second and then a third time. Tulving found
that not all of the same words were recalled across the three occasions, and one word
was recalled on the third occasion that had not been recalled on the earlier trails.
These findings cannot be explained by trace decay because if the trace had decayed it
would have never be available, but retrieval failure theory would argue that different
retrieval cues were used on the three occasions.
- This resulted in the difference in recall.
- Tulving used the term 'CUE DEPENDENT FORGETTING' to explain that in the same cues are not present at
recall as during the original learning, then recall is poor. There are two types of cue-dependent forgetting:
- CONTEXT-DEPENDENT FORGETTING ~ Which occurs if the relevant environmental variables that were present
when learning took place are missing at recall, these variables act as external cues. STATE-DEPENDENT
FORGETTING ~ which occurs in the absence of relevant psychological or physiological variables that were present
during learning, these variables act as internal cues. A study by Bower (1981) showed that when the mood of
participants at learning and recall was matched recall was superior to mismatch of mood at learning and recall.
- Research Study: Godden and Baddeley. Aim: ~ To see if cues from the
environment affect recall. Method: ~ Field experiment was carried out with
deep- sea divers who learned lists of words either on land or underwater
(independent variable). Recall of words (dependent variable) was then
tested in the same or different context. Results: ~ Those who learned and
recalled in different contexts, showed more than a 30 per cent deficit
compared to those who learned and recalled in the same context.
Conclusion: ~ Environmental context affects memory, and superior recall
occurs when environmental conditions at learning and recall match.
Evaluation: ~ Although this was a field experiment which means it is more
ecologically valid than controlled lab studies, the extreme conditions do
not really reflect memory in everyday conditions.
- Evaluation of Retrieval failure: ~ Explains things that cannot be
explained by trace decay theory. ~ Lots of empirical evidence to
support Cue-dependent forgetting. ~ However, evidence has been
criticised, E.G. Bowers study manipulating the mood of participants
under hypnosis has never been replicated. This study also suffers from
dubious ethics. In addition studies have also been carried out in fairly
extreme conditions or where the status is very different whereas in real
life we rarely have to recall things under such extreme conditions.
These studies can therefore lack ecological validity.
- Motivated Forgetting Theory: ~ Suggests that we may be motivated to forget. Freud says that some experiences are so
painful that if they were allowed to enter consciousness they would produce overwhelming anxiety. Instead, these
experiences are repressed and stored in the unconscious, thereby becoming inaccessible. In motivated forgetting, the
original experience has been stored but it has now become inaccessible. The most likely outcome of an individual trying to
retrieve this memory is that it is more likely then to become repressed.
- Research Study: Glucksberg and Lloyd (1967) ~ Aim: To investigate motivated forgetting. Method: ~ Repeated design
experiment participants are required to learn a paired-associate list of words. They were then asked to read a second list of
words some of which were related to the B words on the paired-associate list. The related words on the second list were
accompanied by an unexpected and unavoidable electric shock. Participants were then asked to recall the original A-B list of
paired associate words (dependent variable) Results: ~ The B words that were related to the second list of words leanrt were
forgotten significantly more often than the control words. Evaluation: ~ Ethical implications around the issues of deception
and use of electric shocks in this study. motivated forgetting is also concerned with emotional and personal events which
could effect participants.
- Research Study: Glucksberg and Lloyd (1967) ~ Aim: To investigate motivated forgetting. Method: ~ Repeated design
experiment participants are required to learn a paired-associate list of words. They were then asked to read a second list of
words some of which were related to the B words on the paired-associate list. The related words on the second list were
accompanied by an unexpected and unavoidable electric shock. Participants were then asked to recall the original A-B list of
paired associate words (dependent variable) Results: ~ The B words that were related to the second list of words leanrt were
forgotten significantly more often than the control words. Evaluation: ~ Ethical implications around the issues of deception
and use of electric shocks in this study. motivated forgetting is also concerned with emotional and personal events which
could effect participants.
- Motivated Forgetting Theory: ~ Suggests that we may be motivated to forget. Freud says that some experiences are so
painful that if they were allowed to enter consciousness they would produce overwhelming anxiety. Instead, these
experiences are repressed and stored in the unconscious, thereby becoming inaccessible. In motivated forgetting, the
original experience has been stored but it has now become inaccessible. The most likely outcome of an individual trying to
retrieve this memory is that it is more likely then to become repressed.
- Evaluation of Retrieval failure: ~ Explains things that cannot be
explained by trace decay theory. ~ Lots of empirical evidence to
support Cue-dependent forgetting. ~ However, evidence has been
criticised, E.G. Bowers study manipulating the mood of participants
under hypnosis has never been replicated. This study also suffers from
dubious ethics. In addition studies have also been carried out in fairly
extreme conditions or where the status is very different whereas in real
life we rarely have to recall things under such extreme conditions.
These studies can therefore lack ecological validity.
- Research Study: Godden and Baddeley. Aim: ~ To see if cues from the
environment affect recall. Method: ~ Field experiment was carried out with
deep- sea divers who learned lists of words either on land or underwater
(independent variable). Recall of words (dependent variable) was then
tested in the same or different context. Results: ~ Those who learned and
recalled in different contexts, showed more than a 30 per cent deficit
compared to those who learned and recalled in the same context.
Conclusion: ~ Environmental context affects memory, and superior recall
occurs when environmental conditions at learning and recall match.
Evaluation: ~ Although this was a field experiment which means it is more
ecologically valid than controlled lab studies, the extreme conditions do
not really reflect memory in everyday conditions.
- CONTEXT-DEPENDENT FORGETTING ~ Which occurs if the relevant environmental variables that were present
when learning took place are missing at recall, these variables act as external cues. STATE-DEPENDENT
FORGETTING ~ which occurs in the absence of relevant psychological or physiological variables that were present
during learning, these variables act as internal cues. A study by Bower (1981) showed that when the mood of
participants at learning and recall was matched recall was superior to mismatch of mood at learning and recall.
- Tulving used the term 'CUE DEPENDENT FORGETTING' to explain that in the same cues are not present at
recall as during the original learning, then recall is poor. There are two types of cue-dependent forgetting:
- This resulted in the difference in recall.
- Retrieval Failure: ~ According to retrieval failure theory, memories cannot be recalled
because the correct retrieval cues are not being used. The role of retrieval cues is
demonstrated by the 'TIP OF THE TOUNGE' phenomenon, in which we know that we
know something but cannot retrieve it from LTM at that particular time. Tulving ~
Investigated retrieval failure in LTM. He gave participants a list of words and then
asked them to write down as many as they could remember in any order. Later
participants were asked to recall them a second and then a third time. Tulving found
that not all of the same words were recalled across the three occasions, and one word
was recalled on the third occasion that had not been recalled on the earlier trails.
These findings cannot be explained by trace decay because if the trace had decayed it
would have never be available, but retrieval failure theory would argue that different
retrieval cues were used on the three occasions.
- Evaluation Of Lack of Consolidation: ~ Patients who have been concussed often suffer
retrograde amnesia, which is a loss of memory for events prior to the concussion. This may
be because the consolidation process has been interrupted. ~ Electro- convulsion therapy
(ECT) causes memory loss for events just before the therapy is given. Evidence suggests
that after a one-hour delay between learning and ECT, perfect retention occurs. This
suggests that the essential consolidation period required, to ensure information reaches
long-term store., is up to one hour. There is evidence from both animals and humans to
support the theory that a consolidation process is necessary to prevent memory disruption
and loss.
- Research Study: Yarnell And Lynch (1970) Aim: ~ To investigate memory loss due to
concussion. Method: ~ A field study was carried out with American footballers who
were concussed for a brief period of time during a game. They were approached
immediately as they regained consciousness and asked for details of the events that
occurred in the game just prior to the injury. They were asked again 20 minutes later.
Results: ~ Accurate information was given when the footballers were questioned
immediately after they regained consciousness, but the same information was not
available 20 minutes later. Conclusion: ~ The consolidation process had been
disrupted and therefore the information about the game was not available in
long-term store. Evaluation: ~ Field study, high in ecological validity. Problems
occurred with control however. Ethical implications when questioning patients when
they had only just become conscious.
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