lecture 8 - False memories Flashcards
explain the memory model
sensory memory
to (attention)
short term memory
working memory (rehearsal)
to (encoding and retrieval)
long term memory
what is a false memory
Defined as: “either remembering events that never happened, or remembering them quite differently from the way they happened” (Roediger & McDermott, 1995, p.803)
describe the method of Roediger and mcdermotts 1995 - Experiment 1
examined false memory for related prototype words
- 6 lists of 12 words were presented audtitorially (1 word per 1.5 seconds) followed by a free recall of each list
- saw a list of words and pps rated confidence that each word was on the list (1-4)
lists were composed of 12 related words linked by an omitted prototype word
- examining recall of unsustained ‘critical lure’
explain the results of Roediger and mcdermotts 1995 - Experiment 1
- free recall produced a serial position curve
- recall of words = 0.6
recall of unrelated words = 0.14 (non studied)
recall of critical words = 0.4(non studied)
False memory effect not due to guessing
58% of participants used highest confidence rating (4 = sure that the item was old) for the non-studied critical lure
Whereas 80% of non-studied unrelated words received the lowest confidence rating (1 = sure it was new)
explain why roediegar and mcdermott did the 2nd experiment
The absence of a false memory signature in meta-cognition is important
…
Imagine a witness in a court of law … a confident witness would appear more convincing to a jury
But there is a weak correlation between confidence and eyewitness accuracy (Sporer et al., 1995)
Consider how flashbulb memory for an event (or crime) might be susceptible to false memory and misleading confidence
explain roediegar and mcdermotts study
- As DRM study list is presented a ‘gist’ (general meaning) is developed
Subsequent accurate recall depends upon item-specific memory and ‘gist’
Whereas false memory relies upon ‘gist’ but not item-specific memory
Gist and item-specific recollection can exist in parallel (Brainerd & Reyna, 2005)
Accurate DRM performance necessitates distinguishing between gist and item specific recollection
explain the associative networks of roediegar and mcdermotts stud
Associative networks: seeing a particular word (e.g. ‘plant’) activates related words (e.g. ‘tree’)
The critical word is repeatedly activated in these associative networks and the participant may claim to recall it
Importantly this is not simply an increased familiarity effect (as ‘R’ responses)
what was lodtus and palmers study based upon
false memorys in an applied forensic setting
explain the method of loftus and palmers study
False memory from a witness can result in a conviction
(Loftus & Palmer, 1974)
Participants saw video of an accident and then estimated speed of impact following different vocabulary
explain the results of loftus and palmer
Contacted = 31.8mph Hit = 34mph Bumped = 39.3mph Smashed = 40.8mph
There was no broken glass in the footage but … for those that heard ‘hit’, 14% said they saw broken glass
… for those that heard ‘smashed’, 32% said that they saw broken glass
explain loftus and palmers study on memory malleability
Loftus (1975) subjects viewed film (no barn in film)
“How fast was the white sports car going when it passed the barn while traveling along the country road?”
assessd a week after the experiment about seeing a barn
what are the results of loftus and palmers study on memory malleability
Week later
17% who were asked the misleading question reported seeing a barn
3% asked the control question reported seeing a barn
what is the method of Loftus and Pickrell (1995) study of if you can get people to have memories of events that never happened
Interviewed relatives to generate 3 true stories and one false story about being lost while shopping as a child
Given the stories and asked to recall what they could of the events
what are the results of the study on of Loftus and Pickrell (1995) study of if you can get people to have memories of events that never happened
68% recall of true events
29% recall of false events
True memories were rated as more clear and more words were used to describe them in recall
explain the results of Hyman, Husband, and Billings (1995) study
Hospitalization, birthday/clown, wedding/punch, evacuate/store
80-90% of true events
no false events recalled in first interview
20% in a second interview
Some participants elaborated upon their false memories (added details never presented)
why are falses memories so important in forensic settings
1980s and 1990s spate of criminal trials premised on the recovery of lost memories following therapy
View that following trauma, unpleasant memories are repressed but can later be retrieved intact (e.g. Tarr, 1994)
But might these ‘memories’ arise from suggestive techniques during therapy
what is a suggestive technique during therapy
making people remember things that didn’t happen
what did baioui investigate
whether we can differentiate a memory which is false from a real one
Can you differentiate between true and false memories by physiological responses?
what did baioui hypothosise
“a stimulus that a person has already encountered bears higher significance than a completely unknown stimulus … We therefore hypothesize that stimuli that have been falsely recognized bears less significance than comparable correctly recognized stimuli … reflected in smaller electrodermal responses for falsely as compared to truly recognized stimuli” (p. 2)
what physiological measures can be used to test whether a memory is real or fake
HR, skin concordance, respiration etc.
describe the methodology usd by baioui 2012
- pictorial DRM task
- semantically related component removed from the image
- 20 min retention interval (completed a filler personality questionnair)
- critical lure included a test
what are the results of baioui et al 2012
Standard false memory effect reported
- Higher recognition for related lures compared to unrelated (non-studied) items
- Stronger physiological effects for the true memories versus the false memories (lures)
- Some awareness that the ‘lure’ is false
what did Cabeza et al. (2001) investigete
Neural mechanisms of false memory using fMRI
what was the method used by Cabeza et al. (2001)
List of associated words presented:
“cucumber, pea, potato, onion …”
Different voices alternated for each list
At test participants performed recognition test on three different word conditions …
what were the three word condiditions used by Cabeza et al. (2001)
True Items: items from the list (“onion”)
False Items: items not from list but related (“carrot”)
New Items: items not from list and unrelated (“Belgium”)
what are the results of Cabeza et al. (2001)
- , Dissociation in medial temporal lobe activation
- Hippocampus activation was greater for true (old) items than new items
- But the same activation as false items
- Suggests hippocampus is involved in semantic memory (since items were semantically associated)
- Dissociation in medial temporal lobe activation
- Left parahippocampal gyrus: false items and new items produced similar activation (much less than true/old items)
- Suggests parahippocampal gyrus involved in memory for sensory information
- Lists delivered in different voices!
what does Cabeza et al. (2001) summarise about teh brain regions which play a part in false memories
mixed messages from the medial temporal lobe
- Medial temporal lobe provides different types of messages when stimuli are presented in a false memory paradigm
- Anterior hippocampus suggests that false items are similar to true (old) items
- Correct in respect to semantic information
Posterior parahippocampal activity suggests that false items are similar to new items
- Correct in respect to sensory information
explain what happened in Neuroscience of False Memories: Atkins & Reuter-Lorenz (2011)
an fmri study of the DRM task
what was found in Neuroscience of False Memories: Atkins & Reuter-Lorenz (2011)
- Dorsolateral prefrontal cortex (DLPFC) activation associated with correct rejections of lures
- This part of the brain linked to post-retrieval source monitoring (Achim & Lepage, 2005)
- Areas showing increased activation for correct rejection of lures versus unrelated negative probes (Atkins & Reuter-Lorenz, 2011)
what is the take home message
In recognition and recall, false memories can be induced using semantically related ‘foils’
Not just increased familiarity: participants believe that the item was presented (K and R responses)
False memories of real life events can be induced.
Potentially devastating impact!
Legal context highlights the importance of understanding these memories
Some indication that brain activity differs for true and false memories.
Mixed messages in medial temporal lobe depending on the type of information about an item
