A pioneer of the scientific study of memory: Hermann Ebbinghaus (1850

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Are traumatic memories different in terms of
cognitive mechanisms?

• William James
• An experience may be so exciting emotionally as
  almost to leave a scar on the cerebral tissue -gt
  burnt-in
• -gt may hold for positive and negative
  experiences
• -gt most systematically researched for personal
  events with great negative emotional
  significance, i.e. trauma
• e.g. - collapse of skywalks of Hyatt Regency
  Hotel in Kansas City 1981
• - natural disasters earthquake / tornado
• - combat experience in Vietnam
• - Holocaust survivors
• - rape victims

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Are traumatic memories different in terms of
cognitive mechanisms?

• memory for personal trauma frequently
  characterized by
• vivid intrusive recollections
• -gt very rich in experienced sensory quality
  (flashbacks)
• could reflect vicious cycle of mood-congruent
  memory retrieval driven by anxiety
• difficult to control by individuals who
  experience them
• best coping mechanisms
• - telling story of traumatic event
• - bringing into perspective towards rest of
  life
• - passing of time

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Are traumatic memories different in terms of
cognitive mechanisms?

• How accurate are they?
• intrusive recollections suggest high accuracy
  and persistence
• due to vividness
• -gt Schacter good reason to believe that
  traumatic memories are more accurate than
  those for non- traumatic events
• BUT even traumatic memories are subject to
  distortion
• -gt systematic investigation by Lenore Terr
• research on memory in kids who were part of
  school bus kidnapping at gun point

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Are traumatic memories different in terms of
cognitive mechanisms?

• Lenore Terrs findings
• - initial stress of shock can introduce
  perceptual errors at time of event (related to
  weapon focus)
• - distortions may occur even for initially
  accurately perceived and remembered details
• e.g. man with pillows stuffed into his pants
• cognitive processes at work
• source confusion (own knowledge of event vs
  report by other children/media/police)
• emotionally-driven retrospective bias /
  emotional filtering
• here anxiety at time of retrieval
• -gt recall being safer then they were
• -gt protective mechanism

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Are traumatic memories different in terms of
cognitive mechanisms?

• less well-adapting individuals may develop
  post-traumatic stress disorder
• may be associated with amplified rather than
  reduced perception of threat in memory
  recollections
• -gt related to vicious cycle of mood congruency
• limits for retrospective bias / filtering
• gist of traumatic experience almost always
  remembered well
• e.g. research on concentration camp survivors
• misremembering date of entry but not name of
  camp

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Are traumatic memories different in terms of
cognitive mechanisms?

• Schacter
• even traumatic memories are not 100 accurate
  photographs of the past in our mind but complex
  reconstructions
• emotional states at time of event and at time of
  retrieval play important role in reconstructions

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Importance of accuracy of traumatic memories in
larger context

• large-scale consequences of accuracy vs lack of
  accuracy of autobiographical memories for
  traumatic events
• -gt reports of recovered memory for childhood
  abuse
• psychological consequences for potential
  victims psychological and legal consequences
  for (falsely accused?) perpetrators
• gt hot debate in media, law, academic
  psychology on false-memory syndrome in 1990s

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How much can we trust our episodic memory?

• is there any research evidence to suggest false
  remembering of non-traumatic info from episodic
  memory?
• -gt are all errors in episodic memory errors of
  omission? i.e. reflect unavailability of info?
• -gt or do we also make errors of commission,
• i.e. false remembering of episode or episodic
  detail that never happened or happened in
  different way?
• can you think of example from everyday life?

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Perceptual illusions
Perceptual Illusions
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How much can we trust our episodic memory?

• can we experience memory illusions?
• Def. mis-remembering of info from episodic
  memory without any intention of deception or
  lying
• accompanied by subjective sense of
  accurate remembering

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et Dream Sleep Snore
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Bed Rest Awake Tired Dream Wake Blanket Pillow Pe
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Episodic memory illusions

• memory illusions studied with Roediger- McDermott
  / Deese paradigm
• -  highly robust effect of false remembering of
  critical lures in recall and recognition
• - occur even when subject is informed about
  potential for memory illusions and
  instructed to avoid them
• - underscore typical reliance on semantic gist
  in episodic memory

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Episodic memory illusions
(Roediger McDermott)
experience of false recognition of critical
lures can be accompanied by sense of
remembering (with R/K procedure)
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Episodic memory illusions

• how can we explain memory illusions in paradigm
  by Roediger McDermott?
• -gt activation- source monitoring theory
• at encoding semantic activation of critical
  lure
• at retrieval source monitoring problem
• e.g. did I read sleep or does it seem
  familiar for other reasons?

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Source monitoring framework (MK Johnson)

• Def. source monitoring
• processes that allow us to determine the
  origin of experienced mental events
• in simplest form applies to experience of event
  as perception, imagination / dream, or memory
• every episodic memory has a source defined by the
  conditions under which it was acquired (where and
  when the episode occurred, in what modality it
  was experienced etc.)
• e.g., I remember there was a fire once in the
  dorm
• can also be applied to info retrieved from
  semantic memory
• e.g., I know the meaning of the term retina

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Episodic memory illusions

• how can we reduce memory illusions in paradigm
  by Roediger McDermott?
• -gt providing additional useful info for source
  monitoring
• e.g. study with words and pictures by Israel
  Schacter
• when words are presented simultaneously with
  corresponding picture at encoding, people are
  less likely to falsely remember critical lures
• -gt source monitoring is made easier

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Episodic memory illusions

• can we see illusions similar to those in
  Roediger McDermott paradigm with non-verbal
  materials?
• yes, with semantically categorized picture sets
• (Koutstaal Schacter, 1997)
• -gt similarity among target items produces robust
  memory for semantic content (cats) but poor
  memory for specific perceptual details
• -gt different mechanism at work than in verbal R
  D paradigm, no activation of false lure at
  encoding
• -gt lack of distinctiveness at encoding makes
  accurate remembering difficult

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Episodic memory illusions

• how can we reduce memory illusions in categorized
  picture paradigm?
• -gt change of retrieval focus
• 3-response recognition test rather than simple
  yes/no test
• yes, identical yes, but only related no,
  unrelated
• -gt participants maximize use of info other than
  semantic gist at retrieval
• -gt fewer false alarms to non-studied cats

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Episodic memory illusions Imagination inflation

• do we sometimes confuse whether we imagined
  something or whether it really happened?
• e.g., trying to remember on way to work whether
  I turned off coffee maker
• -gt I know I was planning to do it, but did I
  really?
• -gt typical source monitoring problem!
• important in false-memory debate
• can traumatic memories be planted through
  therapy?
• (see Loftus example)

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Episodic memory illusions Imagination inflation

• experimental demonstration of imagination
  inflation in research by Goff Roediger (1998)
• 3 sessions separated by delays
• 1) study (a) hearing action (e.g. break
  toothpick) (b) hearing and performing action
• 2) imagination session
• imagine performing actions once or more
• (from (a), (b), and new ones)
• 3) recognition and source memory test
• Did you encounter this action in session 1?
• If yes, did you perform or only hear about it?

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Episodic memory illusions Imagination inflation
more frequent imaginings in session 2 lead to
more frequent false remembering of performing
actions (heard only or even never heard at all
in session 1)
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• Study on imagining autobiographical events from
  childhood by Loftus
• three phases
• (1) judge confidence that event occurred
• delay
• (2) imagine that event occurred
• delay
• (3) judge confidence again

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Episodic memory illusions Suggestibility

• Def. suggestibility
• individuals tendency to incorporate misleading
  info from external sources into personal
  recollections from episodic memory
• external sources e.g., other peoples oral or
  written statements, pictures, films

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Episodic memory illusions Suggestibility

• situations in which suggestibility can be
  important factor
• eyewitness testimony in police investigations
  and courtroom
• -gt can reports from eyewitnesses reflect
  memory illusions due to suggestions during
  interrogations?
• recovered memories (of abuse) in psychotherapy
• -gt can they reflect memory illusions due to
  suggestions by therapist?

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Episodic memory illusions Suggestibility

• groundbreaking research by E. Loftus on
  suggestibility in memory
• demonstration of misinformation effect
• when people who witness an event are later
  exposed to new and misleading info about it,
  their recollections often become distorted
• classic experiment with slides showing situation
  that leads to car accident (Loftus, Miller,
  Burns, 1978)

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Misinformation effect
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Misinformation effect

• classic experiment with slides showing situation
  that leads to car accident (Loftus, Miller,
  Burns, 1978)
• subsequent to watching slides, subjects receive
  questionnaire with misleading, consistent, or no
  info about traffic sign
• variation of delay between slide show and
  questionnaire (20 min vs 1 week)
• Critical forced-choice recognition memory test
• Did you see stop- or yield-sign?

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Misinformation effect

• even with short delay less accurate memory after
  misleading info
• with delay (i.e. fading of original memory),
  higher susceptibility to memory errors

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Misinformation effectFurther research questions

• How can the effect best be explained?
• actual memory impairment (over-writing)
• versus
• demand characteristics of situation
  (compliance)
• related question
• Do subjects really remember misleading info as
  original? (i.e. is it truly memory illusion?)
• Or can they keep sources apart if asked
  directly?

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Misinformation effectFurther research

• research by Lindsay Johnson addresses nature of
  errors
• change of questions at time of memory testing
• simple recognition vs source monitoring
  question
• Did you see info in slide?
• Did you see info in slide, read it, both, or
  neither?
• -gt more memory errors with recognition than
  with source monitoring questions
• -gt suggests when demand characteristics are
  changed and source info is emphasized, people
  make less errors
• BUT some errors occur even on source questions
• -gt suggests that some but not all errors
  reflect actual mis-remembering (illusions)