Memory
Starter Questions
• Is forgetting losing information or simply not being able to
recall it?
• How can you tell the difference?
• When was the last time you forgot something?
• Had you forgotten or was it failure to recall?
• What type of information are you more likely to forget?
(names/dates/faces/facts/numbers/conversations/experiences
etc)
• Think about when you forget. Are you more likely to forget in
a particular situation or specific emotional state?
Forgetting in STM – Trace Decay
• Assumes that memory traces are created during encoding
(physical existence)
• Lack of rehearsal means that this trace slowly disappears (decays).
• Explains why things are forgotten over time.
• This deals with forgetting due to lack of availability not lack of
recall (the memory is not there)
• Hebb (1949) argues that during learning that the trace which is
formed is timid and fragile. With learning (repetition), it grows
stronger until a constant trace is formed through neurochemical
and neuroanatomical changes. According to the theory, short term
forgetfulness happens because the active trace is disturbed.
Forgetting in STM – Displacement
Theory
• STM has limited capacity so when we take in new
information it pushes other information out.
Research
• Peterson & Peterson (1959). In terms of decay theory,
the trace could not grow stronger and so broke down.
OR as ppts were counting the information could just
have been displaced.
• Reitman (1974) During retention interval ppts asked to
listen out for a tone rather than being given new info.
During a 15 second interval word recall fell by 24%.
Trace decay? OR were ppts thinking about what to
have for dinner? Counting the tiles on the wall?
Waugh and Norman (1965) (see handout)
Aim: to test if forgetting in STM is due to trace decay or
displacement.
M&P: 4 students – 90 x 16 digit lists and asked to recall the
number which came before the first occurrence of a probe
number.
 2 conditions (individual groups)
 A – were given the list at a fast pace (4 digits per second)
B – given the list at a slow pace (1 digit per second) – trace
decay
 If forgetting was a result of trace decay then group B would
have lower results. If forgetting is a result of displacement then
there would be no difference in results.
 Results: Found that recall was better when recalling from the
end of the list – supporting displacement theory.
Decay Theory - LTM
Same theory as decay theory in STM but that
the decay is much more likely to be a result of
brain damage.
•
• Lashley (1931) trained rats to learn mazes then
removed parts of their brains. Correlation
between amount removed and amount of
forgetting. Evidence for physical decay.
•Very little evidence to definitively support this
theory.
Interference Theory - LTM
•
Proactive interference – when past learning interferes with
attempts to learn something new. (Old memories disrupt new
ones)
• Retroactive interference – when current learning interferes
with old learning. (New memories disrupt old ones)
• Eg – learning new mobile numbers. Keep giving out your old
number – proactive interference.
• If that number was only temporary and you need to go back
to giving out your original number but give out the temp
number – retroactive interference
• The information has to be similar in order for interference to
occur – studying 2 languages, places, times, numbers etc
Interference Theory
• Lab experiments – lacks mundane realism/ecological
validity
•Extent to which this theory can be attributed to
forgetting remains unclear.
Cue-dependent forgetting - LTM
• This theory assumes that forgetting is a result of lack of
retrieval (memory is available but not accessible)
•2 types of cues that can trigger memories:
• Context dependent forgetting (external)
• Abernethy (1940)
• cues from our environment help us remember (songs, smells,
places, etc)
• State-dependent forgetting (internal)
• Goodwin et al (1969); Hardman (1998)
• When the physical/emotional state we are in triggers a
memory. (stress, drunk, happy, etc)
Cue-dependent forgetting
•Lab experiments – lacks mundane realism
• Procedural memory?
Interference or lack of cues?
•Tulving and Psotka, 1971
•Ppts given 6 lists of 24 words each divided into 6 categories.
•After each list ppts to free recall the words they could remember.
•Results showed that the participants who had been given all 6 lists performed
worse than other participants who were only given 1 or 2 lists. This is evidence
for retroactive interference.
•After they free recalled the final list they were then asked to recall all the
words from all the lists but were given the category names (cued recall).
•The cued recall test found that all participants recalled, on average, 70% of
the words they had been given – interference disappeared.
•Conclusions – interference effects mask what is available – the information is
there it’s just more difficult to retrieve. Forgetting is a result of retrieval issues
not encoding.
Motivated Forgetting
• Psychoanalytical approach
•Wanting to forget either:
• Consciously (suppression)
• Unconsciously (repression)
• You may want to consciously forget something because
you just don’t want to do it eg when you have been asked
to do the dishes, tidy your room, homework, etc
Repression
• Freud’s theory that the ego is trying to protect itself from an
emotional conflict.
• The traumatic memory is pushed into the unconscious in order to
protect the individual. This memory can, however, still affect the
conscious mind.
• Can be recovered during RMT.
Conscious mind
• False memories?
Unconscious mind
Repressed
traumatic
memory
Research
• Bradley and Baddeley, 1990, word association task – ppts found it
more difficult to remember what their responses were to emotionally
charged words than to neutral words straight away but could recall
them better over time. Strong emotions suppress SMT but enhance
LMT OR strong emotions are initially repressed but disappears over
time?
• Williams, 1994 – 38% couldn’t recall being sexually abused. 16%
who did claimed that the memory had been recovered. No memory
of childhood abuse is common and that recovery is possible.
•Karon and Widener, 1997 – WWII veterans – mental illness alleviated
when painful memories were recovered in therapy.