Theories of Forgetting
o Availability refers to whether info is still actually stored.
o Accessibility is whether or not it can be retrieved.
o Freud believed that no memories were forgotten but forgetting was
merely failure to retrieve. Evidence for this came from Penfield 1969
who when stimulated the surface of the brain in epilepsy patients
found it led to recall of long forgotten memories. However only a small
amount of patients had memories triggered, could be they are merely
fantasies.
Displacement
o Forgetting in STM due to Lack of availability
o Refers to limited number of slots as identified by Miller.
o Some existing info is displaced from STM as a new piece is taken
in.
o Suggests if info is to be retained it must be processed into LTM.
Shallice
Procedure- a serial probe task was used in which participants were
presented with 16 digits, at the rate of either 1 per second or 4. One of the
digits was the probe, and was repeated in the sequence. Participants asked
which number followed it.
Results- Recall was much better when only a few digits followed the probe.
Recall was also better in the more rapid presentation condition.
Conclusion- findings that recall was better when only a few digits followed
probe supports displacement. Differences in speed of presentation explain
trace decay.
o Primacy-recency effect can also be explained in terms of
displacement. 1st items LTM, last items STM. Those in middle
displaced.
Trace Decay
o Both STM & LTM due to lack of availability.
o Learning something creates a memory trace which gradually fades.
Evidence comes from Brown-Peterson technique. Peterson & Peterson
found tat the counting task brought about forgetting and suggested
that this was because rehearsal which is necessary to replenish the
decay was prevented. However it could be that displacement caused
forgetting since the numbers counted backwards are put into the
STM and so displace the trigrams.
o Shallice’s findings that the more rapid presentation led to less
forgetting also supports the idea of trace decay.
o Procedural memory- even when not rode a bike for a long time, so
memory cant be replenished, people have little difficulty in riding
again, also true of faces (Bahirck et al 1975- participants could
identify classmates faces 90% of the time many years after
graduation. Showing that memory faces shows little trace decay)
Interference
o Memories may be interfered with either by what we have learned
before, or by what we may learn in the future.
o STM & LTM due to lack of accessibility.
o Similarity is main factor in forgetting as similar memories compete
causing interference.
o Proactive interference- old knowledge interferes with new
knowledge. If wear watch on right hand instead of left, 1st few
times you will glance at left hand then right hand.
Loess study- presented participants with 3 names of animals, after
each list counted backward from 15 and then recall the list. They did
this 6 times. Later lists not recalled as well as early ones. Earlier lists
interfered with later ones. Recall was improved when a new subject
was introduced such as vegetables.
o Retroactive interference- new knowledge will interfere with old
knowledge
Proactive- Learn A: Learn B= interference from A affects recall of B
Retroactive- Learn A: Learn B= interference from B affects recall of A
McGeoch & McDonald found that participants learning a word list, forgetting
was greatest when a subsequent interference task was similar to what had
been learned originally. Little effect on recall from interference when
unrelated material but more when it involved antonyms. Most forgetting
occurred when synonyms of original list were used.
Retrieval Failure
o LTM forgetting due to lack of accessibility
o Cue-dependent forgetting refers to context and state dependent
forgetting, Tulving suggested that info about physical surroundings
and psychological state of the learner is stored at the same time
as info is learnt.
o Reinstating the context can provide retrieval cues to help with
recall.
Godden & Baddeley 1975
Procedure- diver participants learned a list of words either on land or
underwater. Later both groups were tested for their recall either on land or
underwater.
Results- the divers who learned words underwater recalled more accurately
when underwater. The divers who learnt and tested on land recalled them
more accurately.
Conclusion- recall of info is better in the same context in which it was
learned.
Zechmeister & Nyberg suggest that just imaging the context is enough to
provide retrieval cues.
o State dependent- need to be in same physical state as when you
learnt it. Goodwin found when people were drunk they were more
likely to recall info learnt that they learnt when in the same state.
E.g. when they hid money.
Miles & Hardman 1998
Procedure- participants learned lists of words either while at rest or
exercising on bicycles. Recall was tested in either the same state of
alternate state.
Results- words learned during exercise were best recalled during exercise,
those learned at rest were best recalled in the same state.
Conclusion- physical state provides cues to assist recall.
o Recall improved when people are in the same emotional state as during
learning, Bower study when they were hypnotised to imagine happy or
unhappy.
Theory can explain why some forgetting occurs but we can not assume all
information in the LTM is recoverable if appropriate cues are present.
Important application to cognitive interview to question EWT.
Repression
o Freud suggested that we forget because there is great anxiety
associated with certain memories, and they psyholoigcal pain would be
too much for us to deal with. When this is the case we may use the
unconscious defence mechanisms. The memory exists but is pushed
into the unconscious. E.g. child abuse.
o Hard to replicate feuds theory experimentally but attempts have
been made: Levinger and Clark 1961.
Procedure- participants were asked to give immediate free association to
negatively charged words and neutral words. They were then given the
cue words and asked for the association they had made.
Results- participants took longer to provide associations to –ve charged
words, and also showed a higher GSR to them. –ve associations were
remembered less well than those of neutral.
Conclusion-relative inaccessibility of –ve charged words and higher GSR
provided a link between emotion and forgetting, so lending some support
to Freud’s idea of repression.
Parkin et al 1982- found that although words that are –ve charged are
poorly recalled immediately, this effect is reversed later on.
Flashbulb memories- goes against repression because something that is
traumatic should theoretically be repressed, however people tend to
remember vast amounts of detail suggesting that high levels of
emotional distinctiveness of an event leads to a better ability to recall
it.
Lack of consolidation
o When we take new info a certain amount of time is needed for
changes to take place in the nervous system-consolidation process.
o During this period info is moved from the STM to the LTM.
o Experiments been conducted to show this period.
Norrie & Henry 1978
Procedure- participants practised climbing a free-standing ladder for 20 1
minute trials separated by one minute periods of practise on a different skill
called the pursuit rotor task, which involves tracking a light moving along a
circular track. They were then tested on the ladder climbing task a week
later. A control group were also used but used the rotor task period as a
rest period.
Results- for the controls there was no deficit in the ladder climbing task.
The experimental group however showed a memory deficit when tested.
Conclusion- the rotor task interfered with consolidation of the ladder
climbing task, so that the gain in skill was not processed into the LTM.
Consolidation process effected when damage to hippocampus, like HM,
unable to transfer info from STM to LTM.
Yarnell & Lynch
This study involved interviewing American footballers after they had
received a knock on the head during a game. If they were questioned
immediately they came off the field, they were able to recall perfectly what
the state of play had been. If questioning was delayed, their memory for
play immediately before the injury had disappeared completely. This
suggests that the head injury had prevented them from consolidating the
memory.
However it may be that all the attention they were receiving had caused
that memory to be displaced from the STM. Can’t tell which problem caused
the loss of memory as both are due to lack of availability.
Vanderploeg 2001
Found that traumatic brain injury (TBI) can lead to loss of consolidation.
TBI patients showed no deficits in encoding or retrieval in comparison to
matched controls, but their pattern of memory deficit supported the idea
that the consolidation process was impaired.
Giambra & Arenberg found that ageing affects the consolidation process as
older participants have greater deficits over shorter periods of time, which
they linked to the consolidation process.