When memory fails us

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When memory fails us

• Dr. Jenny Wilson

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Lost? Or confused?

• Why do we forget?
• What other mistakes does our memory make??

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What is forgetting?

• To understand how the memory system works, it is
  important to look at some of the reasons why we
  lose information - in other words, how we forget.
  We will look at some psychological explanations
  of forgetting
• The inability to retrieve previously available
  information.
• It is useful to think of forgetting as a problem
  of either 'availability (it was never properly
  stored and therefore is not available), or
  accessibility' (it was stored but the
  information cannot presently be accessed).

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Theories of forgetting
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Theories of Forgetting

• Poor encoding theories
• Decay theories
• Interference theories
• Retrieval-cue theories
• Repression- (Freud)
• Damage (e.g. amnesia)

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When do we forget ?
Forgetting can occur at any stage
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Forgetting as encoding failure

• Information never encoded into LTM

X
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Encoding Failure

• Where is the number 0 on your calculator?
• What letters accompany number 1 on your mobile
  phone?
• According to this theory, objects seen
  frequently, but info never encoded into LTM

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Forgetting as retrieval failure
Not all forgetting is due to encoding
failures Sometimes info IS encoded into LTM, but
we are unable to retrieve it.
X
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Tip of the tongue phenomenon

• a.k.a. TOT experience (Brown McNeill, 1966
  Brown, 1991)
• Cant retrieve information that you absolutely
  know is stored in your LTM
• TOT is a near-universal experience in memory
  recollection involving difficulties retrieving a
  well-known word or familiar name.
• Two key features of TOT are inaccessibility and
  imminence (Brown, 1991)
• Example http//www.missionimpossible.com/
• But who directed it??????
• Evidence of forgetting as an inability to
  retrieve information.
• BUT Why cant we retrieve info?

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Retrieval failure theories

• Decay theories
• Interference theories
• Retrieval cue theories

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Trace Decay Theory

• Biology-based theory
• When new memory formed, it creates a memory trace
• a change in brain structure or chemistry
• If unused, normal brain metabolic processes erode
  memory trace

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Decay theories evidence

• Memories fade away or decay gradually if unused
• Time plays critical role
• Ability to retrieve info declines with time after
  original encoding
• Forgetting curve Ebbinghaus, (1885)
• STM rapid forgetting (Peterson Peterson 1959)

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Decay theories

• Theory not widely favored today.
• Information CAN be remembered decades after
  original learning even if unused since original
  learning (name of old school friend)
• Flashbulb memories are another piece of
  contradicting evidence. A flashbulb memory is a
  memory laid down in great detail during a
  personally significant event, e.g. shocking event
  of international importance.
• Flashbulb memories are perceived to have a
  "photographic" quality. (Brown and Kulik, 1977)
  found highly emotional memories (e.g. hearing bad
  news) are often vividly recalled, even some time
  after the event.
• Sleep is believed to play a key role in halting
  trace decay, although the exact mechanism of this
  is unknown
• Decay Theory more applicable to STM

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Interference theories

• Memories interfering with memories
• Forgetting NOT caused by mere passage of time
• Caused by one memory competing with or replacing
  another memory
• Two types of interference

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Two types of interference
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Retroactive interference

• When a NEW memory interferes with remembering OLD
  information
• Example When new phone number interferes with
  ability to remember old phone number.

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Retroactive interference

• Example Learning a new language (Spanish)
  interferes with ability to remember old language
  (French)

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Proactive interference

• Opposite of retroactive interference
• When an OLD memory interferes with remembering
  NEW information
• Example Memories of where you parked your car on
  campus the past week interferes with ability find
  car today

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Proactive interference

• Example Previously learned language interferes
  with ability to remember newly learned language

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Retrieval failure Retrieval cue theories

• What is a Retrieval cue
• a clue, prompt or hint that can help memory
  retrieval
• Forgetting the result of using improper retrieval
  cues

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Recall vs. Recognition tests

• Importance of retrieval cues evident in recall
  vs. recognition tests
• Recall tests - must retrieve information learned
  earlier
• Examples Fill-in-the-blank test essay exams
• Recognition tests - only need to identify the
  correct answer
• Example Multiple choice tests

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What is the capital of Bulgaria?

• Raise your hand if you know the answer

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What is the capital of Bulgaria?

• A. Arbanassi
• B. Sofia
• C. Stockholm
• D. Nessebur
• Raise your hand if you know the answer
• Which was easier recall or recognition?
• NB unique case of a patient with an aneurysm of
  the anterior communicating artery. Patient showed
  a dissociation between very poor performance on
  recognition tests (on which the patient'
  performance was as poor as that in classical
  amnesic patients) and normal performance
  (estimated by the number of correct responses) in
  recall. (Delbecq-Derouesné, Beauvois Shallice
  1990)

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Which retrieval cueswork best?

• According to the Encoding specificity principle
  (Tulving, 1974) cues used during initial learning
  more effective during later retrieval than novel
  cues
• In other words, most effective retrieval cues are
  those that were stored along with the memory of
  the experience.

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Which retrieval cues work best?

• Context-dependent memory
• Improved ability to remember if tested in the
  same environment as the initial learning
  environment
• Better recall if tested in classroom where you
  initially learned info than if moved to a new
  classroom
• If learning room smells of chocolate or
  mothballs, people will recall more info if tested
  in room with the same smell
• compared to different smell or no smell at all

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Context dependent effects

• Time of day is also important

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Context-dependent effects

• Words heard underwater are best recalled
  underwater
• Words heard on land are best recalled on land
• Godden Baddeley (1975)

recall
Water/ land
Land/ water
Water/ water
Land/ land
Different contexts for hearing and recall
Same contexts for hearing and recall
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State-dependent effects

• Recall improved if internal physiological or
  emotional state is the same during testing and
  initial encoding
• Context-dependent - external, environmental
  factors
• State-dependent - internal, physiological factors

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State-dependent effects

• Mood or emotions also a factor
• Bipolar depressives
• Info learned in manic state, recall more if
  testing done during manic state
• Info learned in depressed state, recall more if
  testing done during depressed state (Reus
  Weingartner 1979)

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State dependent effects
Performance better if Happy during recall/
Unhappy during learning
Happy during learning
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Memory Errors

• Our memory is not a direct recording of events.
  Think about what this tells us about theories
  i.e. reconstructive. Accordingly we can make
  errors when fitting in or recalling the memory.
• Common examples include
• Source confusion (or source monitoring error)
• Confabulation
• Illusory memory
• Social Contagion and Misinformation effect

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Source Monitoring

• Source monitoring allows us distinguish the true
  source of the information.
• Sometimes we may misattribute our memory to
  incorrect sources.
• For example forget who told us something.
• In EWT Source monitoring error therefore is the
  process by which a memory derived from once
  source (the post event info provided by
  experimenter) is misattributed to another source
  (the witnessed event) or is attributed to both
  sources. Pickel, 2004)
• Or we think the clerk was the assailant.
• Pickel, K. L. (2004). When a lie becomes the
  truth The effects of self-
• generated misinformation on eyewitness memory.
  Memory, 12(1), 14-26.
• Schreiber, T.A., Sergent, S.D. (1998). The role
  of commitment in producing misinformation effects
  in eyewitness memory.  Psychonomic Bulletin
  Review, 5 (3), 443-448.

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Eyewitness testimony

• Recall not an exact replica of original events
• Recall a construction built and rebuilt from
  various sources
• Often fit memories into existing beliefs or
  schemas
• Schema - mental representation of an object,
  scene or event
• Schemas are integrated chunks of knowledge stored
  in long-term memory that allow us to form
  expectations and make the world a reasonable
  predictable place.
• Example schema of a farm may include cows, sheep
  pigs hay, etc.

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Schema reconstructive memory

• Bartlett (1932) argued that we rely on schemas as
  well as content to remember stories.
• In his classic experiment War of Ghosts,
  participants were asked to recall a story from a
  different culture.
• Typically the following errors were made
• Rationalisation errors making the story read
  more like a typical English story. (majority of
  errors fell into this category)
• Flattening errors failure to recall unfamiliar
  details.
• Sharpening errors elaboration of certain
  details.

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Schema Reconstructive memory

• Bartlett (1932) argued memory for the precise
  material presented is forgotten over time,
  whereas memory for the underlying schemas is not.
  
• Accordingly, rationalisation errors (which depend
  in schematic knowledge) should increase in number
  at longer retention intervals.
• Bartlett believed distortions occur because of
  schema-driven reconstructive processes operating
  at the time of retrieval.
• Support for Bartlett's prediction about
  rationalisation errors was provided by Sulin and
  Dooling (1974).
• However, Bransford and Johnson (1972) suggested a
  more constructivist approach to Bartlett's
  assumption of memorial distortionsthat schemas
  can also influence story comprehension.

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Memory distortion

• Memory can be distorted as people try to fit new
  info into existing schemas
• Giving misleading information after an event
  causes subjects to unknowingly distort their
  memories to incorporate the new misleading
  information.

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Loftus experiment

• Subjects shown video of an accident between two
  cars
• Some subjects asked How fast were the cars going
  when the smashed into each other?
• Others asked How fast were the cars going when
  the hit each other?

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Loftus Findings
speed
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Social Contagion effect

• The finding that a persons recall in a
  collaborative setting can be affected by others.
• In other words our memories can be infected by
  the recall of others. Roediger, Meade Bergman
  (2001)
• How might this play a role in EWT?

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Illusory memory or false memory

• Recalling something that didnt happen.
• Indirect tests of memory used (Roediger
  McDermott, 1995 Johnasson Sternberg 2002)
• theme and associated words intrude.
• Cog neuroscience evidence for real memories ERP
  study Fabiani et al (2000)

• Word list

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False memory

• false memory is a memory of an event that did not
  happen or is a distortion of an event that did
  occur as determined by externally corroborated
  facts.
• False memory syndrome (FMS) is the term for the
  hypothesis describing a state of mind wherein
  sufferers have a high number of highly vivid but
  false memories, often of abusive events during
  their childhood.
• It has been suggested that the therapists may
  inadvertently implant suggestions which lead to
  the false memory.

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Confabulation

• The introduction of inaccurate detail into
  memories. (Also a false memory)
• Confabulation is the confusion of imagination
  with memory, and/or the confusion of true
  memories with false memories.
• Patients with Korsakoff's syndrome
  characteristically confabulate by guessing an
  answer or imagining an event and then mistaking
  their guess or imagination for an actual memory.
  (Dalla Barba, Cipolotti Denes 1990)
• Stroke patients with damage to the non-dominant
  hemisphere and the frontal lobe may also
  confabulate. (Nersessian 2000)
• Confabulation may be a problem in the reality
  monitoring phase of source monitoring.
• Hirstein (2004) describes confabulation as the
  failure of a normal checking or censoring process
  in the brain the failure to recognize that a
  false answer is fantasy, not reality.