Transcript A pioneer of the scientific study of memory: Hermann

Please rate for each of the
following words how much
you like what it refers to!
Bed
Rest
Awake
Tired
Dream
Wake
Blanket
Pillow
Peace
Yawn
Snore
Slumber
Drowsy
Please rate for each of the
following pictures how
much you like it!
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’ -> “burnt-in”
->may hold for positive and negative experiences
->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
Are traumatic memories different in terms of
cognitive mechanisms?
• memory for personal trauma frequently characterized by
vivid intrusive recollections;
-> 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
Are traumatic memories different in terms of
cognitive mechanisms?
• How accurate are they?
intrusive recollections suggest high accuracy and persistence
due to vividness
-> Schacter: good reason to believe that traumatic
memories are more accurate than those for nontraumatic events
BUT even traumatic memories are subject to distortion
-> systematic investigation by Lenore Terr:
+ research on memory in kids who were part of school
bus kidnapping at gun point
Are traumatic memories different in terms of
cognitive mechanisms?
• Lenore Terr’s 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
-> recall being safer then they were
-> protective mechanism
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
-> 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
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
Importance of accuracy of traumatic memories
in larger context
• large-scale consequences of accuracy vs lack of accuracy of
autobiographical memories for traumatic events
->
reports of recovered memory for childhood abuse
+ psychological consequences for potential victims
+ psychological and legal consequences for (falsely
accused?) perpetrators
> hot debate in media, law, academic
psychology on false-memory syndrome in 1990s
How much can we trust our episodic memory?
• is there any research evidence to suggest false remembering
of non-traumatic info from episodic memory?
-> are all errors in episodic memory errors of omission?
i.e. reflect unavailability of info?
-> 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?
Perceptual illusions
Perceptual
Illusions
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
Indicate for each of
the following words
whether you heard it
earlier:
Awake
Brain
Computer
Blanket
Dream
Sleep
Snore
Bed
Rest
Awake
Tired
Dream
Wake
Blanket
Pillow
Peace
Yawn
Snore
Slumber
Drowsy
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
Episodic memory illusions
(Roediger &
McDermott)
experience of false recognition of critical lures can be
accompanied by sense of ‘remembering’ (with R/K procedure)
Episodic memory illusions
• how can we explain memory illusions in paradigm by
Roediger & McDermott?
-> 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?
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’
Episodic memory illusions
• how can we reduce memory illusions in paradigm by
Roediger & McDermott?
-> 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
-> source monitoring is made easier
Indicate for each of
the following pictures
whether you saw it 1
hour ago!
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)
-> similarity among target items produces robust
memory for semantic content (‘cats’) but poor
memory for specific perceptual details
-> different mechanism at work than in verbal R & D
paradigm, no ‘activation’ of false lure at encoding
-> lack of distinctiveness at encoding makes accurate
remembering difficult
Episodic memory illusions
• how can we reduce memory illusions in categorized
picture paradigm?
-> change of retrieval focus:
3-response recognition test rather than simple yes/no
test:
yes, identical – yes, but only related – no, unrelated
-> participants maximize use of info other than
semantic gist at retrieval
-> fewer false alarms to non-studied cats
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
-> I know I was planning to do it, but did I really?
-> typical source monitoring problem!
• important in false-memory debate:
can traumatic memories be ‘planted’ through therapy?
(see Loftus example)
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?
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)
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
Episodic memory illusions: Suggestibility
• Def.: suggestibility
individual’s tendency to incorporate misleading info from
external sources into personal recollections from
episodic memory
[external sources; e.g., other people’s oral or written
statements, pictures, films]
Episodic memory illusions: Suggestibility
• situations in which suggestibility can be important
factor:
+ eyewitness testimony in police investigations and
courtroom
-> can reports from eyewitnesses reflect memory
illusions due to suggestions during interrogations?
+ recovered memories (of abuse) in psychotherapy
-> can they reflect memory illusions due to
suggestions by therapist?
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)
Misinformation effect
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?
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
Misinformation effect
Further 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?
Misinformation effect
Further 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?
-> more memory errors with recognition than
with source monitoring questions
-> suggests when demand characteristics are
changed and source info is emphasized, people
make less errors
BUT some errors occur even on source questions
-> suggests that some but not all errors reflect
actual mis-remembering (illusions)