Reliability Of Eyewitness Testimony Flashcards
Two models of recognition
Recollection - intentional, conscious, affected by attention
Familiarity- automatic, conscious, not affected by attention, supports priming
Susceptibility of memory; changing an existing memory
1) following exposure to post event information (the misinformation effect)
2) after discussing memories with a co witness (the memory conformity effect)
3) after suggestive questions in an interview or when cross examined in court (interrogative suggestibility)
Why is our memory susceptible to misinformation?
Memory is not a passive store or an exact replica of original events
Humans are best adapted for acquiring knowledge- not providing verbatim accounts
Memory is reconstructive
Exposure to Post Event Information
PEI
Study phase: participants exposed to an event
Misinformation phase: after a period of time, half the participants receive misleading PEI (misinformation) about the event, e.g. They could be asked to read a narrative about the event that contains errant details.
Test phase: participants are given a memory test about the originally encoded information.
The misinformation effect
Misled participants often report the suggested misinformation at test, even when they have been asked to recall the original details of an event
Why do we report Post-Event Information at test
Trace alteration
- original memory trace is overwritten
- creates some kind of memory blend
Trace Blocking
- access to original memory is blocked by the suggested information
Source monitoring
- confusion about source of memories
Social demand
- PEI is reported at test due to processes operating at the time of retrieval, such as task demands or a motivation to be accurate.
Loftus 1978
Participants view slides:
- car turns right at intersection and hit pedestrian
- half see a stop sign, half see a yield sign.
Misinformation phase:
Participants hear a narrative describing the accident which is either consistent or misleading.
Test phase:
Recognition tests for slides
Results:
Critical slides to test for misinformation effect (stop vs yield)
75% of control participants chose correctly
Only 41% of misled participants were correct
McCloskey & Zaragoza 1985
Critique
Criticise Loftus’ methodology
- the final test does not allow the researchers to draw the bold conclusions that were made about misinformation overwriting an original memory trace
Suggests different interpretations of the data, that do not necessarily imply trace alteration
- both traces exist, but participants select the misinformation because they feel obliged, or trust the experimenter more than own memory.
- the initial detail was never encoded, so participants select the misinformation as its the only familiar option.
McCloskey & Zaragoza’s 1895
Believed that misinformation was due to the influences through reports of subjects who never encoded the original event. Subjects would be lured into producing the misinformation, and after deliberation conclude it to be correct.
Participants viewed a yield sign
Half the participants hear about the car passing a stop sign, the other half heard that it’s a yield sign.
Yield vs. Stop sign. 35% drop in accuracy for participants exposed to misinformation.
Yield v NO U TURN sign = high accuracy, and no difference in accuracy between conditions n
This methodology controls for response biases and task demands by excluding the misinformation item as a response choice.
If original memory trace was overwritten, performance would end at chance, performance would be at chance for the misled participants
The misinformation effect summary
To fully understand how suggestible our memory is, it is vital to design well controlled experiments
Recent eye witness research, employing valid methodological procedures, supports the view that both the original information and the PEI coexist in memory.
People sometimes errant lay report post-event at test when the information is available
Okado & Stark 2005
Standard three stage procedure
Man stealing a girls wallet.
Next some subjects got some misinformation about the event, such as the fact that the girls arm was hurt in the process rather than her neck.
Subjects asked to remember what they saw, many claimed they saw the misinformation details in the original event.
The misinformation was remembered as being part of the original event about 47% of the time.
Robust impairment of memory was produced by exposure to misinformation - the misinformation effect.
Okado & Stark 2005
Neural activity
They went on to show neural activity that occurred while the subjects processed the events and later the misinformation predicted whether a misinformation effect would occur.
The when question
Greater susceptibility to misinformation
Loftus 1978
Tousignant 1986
Loftus 1978: People are particularly prone to having their memories affected by misinformation when it is introduced after the passage of time has allowed the original event to fade.
Reason: event memory is weakened, less likelihood that a discrepancy is noticed while the misinformation is being processed.
Tousignant 1986: proposed a fundamental principle in determining when changes in recollection after misinformation would occur: the discrepancy detection principle.
Assefi & Garry 2002
Scoboria 2002
Temporarily changing someone’s state can increase misinformation effects.
If people are good they have drank alcohol they are more susceptible.
When people are hypnotised they are more susceptible
Effects people’s abilities to detect discrepancies
Warning
Greene 1982
Eakin 2003
A warning given after misinterpretation had been processed did not improve ability to resist the misinterpretation effect.
Misinterpreted information had already been encore rated into the memory and altered memory now existing in the mind of the individual.
When people get a warning they suppress the misinformation and it has less ability to interfere.
Suppression may have more trouble when misinformation is too accessible.
Ceci & Bruck 1993
Karpel 2001
Younger children are more susceptible to misinformation than are older children and adults
Elderly are more susceptible than are younger adults
Effect of age may present an idea of cognitive resources, as misinformation effects are stronger when attentional resources are limited.
Personality variables and susceptibility
The more one has self reported lapses in memory and attention, the more susceptible one is to misinformation effects.
Electrophysical studies
Sensory activity is greater for true recognition than false recognition
The hippocampus and a few other cortical regions come into play when people claim to have seen tags they did not see
Suggestible because they want thief report to be correct
Hardin & Higgins 1996
Allan 2012
Allan & Gabbert 2008
Individual doubts their accuracy of this own memory of when the information encountered from another individual convinces them that their initial judgement might be wrong.
Those who believe they have inferior memory quality to others were more likely to become influenced by, and subsequently report items of errant PEI encountered for another person.
Overt confidence with which individuals make their assertions to each other can operate systematically as a cue that promotes conformity
Emotion & suggestibility
Jacobs & Nadel 2006
Roozendal 2000
Gabbert & Hope 2016
Emotionally arousing events are generally remembered better than natural events.
Stress hormones can enhance memory performance
High stress levels experienced in naturalistic settings generally impairs memory and these detrimental effects have been well documented
Suggestibility & stress during encoding
Morgan 2013
Increased level of suggestibility have been associated with stress at encoding.
800 soldiers taking part in survival training. Found those following a high stress interrogate were 40% more likely to identify the person shown at misinformation phase as their interrogator than those who did not receive this information.
27% soldiers mistaken to report their interrogator threatened them with a weapon.
Intoxication & memory
Basic research on effects of alcohol on memory tend to show memory impairment.
Lab study: found intoxicated witnesses were no less accurate or vulnerable to suggestion than sober witnesses in their recall of staged events in a lab based study.
Field study: although accuracy did not differ, significantly less information was provided.
Also found alcohol intoxication impaired memory and increased susceptibility to suggestive questions during an immediate interview.
Suggestibility & alcohol
Gudjonsson, Hannesdottir 2002
High rates of drug and alcohol intoxication associated with false confessions.
Subjects experiencing withdrawal symptoms may be particularly vulnerable to suggestion and false confession.
Working memory suggestibility
Jaschinski & Wentura 2002
Working memory capacity relates to the effect of misinformation on memory.
Found participants with a large working memory capacity were less susceptible to the misinformation.
May be because people with greater memory capacity build a coherent mental model of events during the encoding phase.
Thus they are able to reject misinformation because they recognise it contrasts with their own memory, or because their mental model represents the event is already detailed so additional information is ignored.
Been found working memory capacity negatively associated with suggestibility.
Discussing memories with a co witness
Crimes often have more than one witness
86% surveys found witnesses admitted to they had discussed the event with co witness before being interviewed by the police
Why report unseen information
Normative motivations to conform
Informational motivations to conform
Memory distortion
Normative: reflects a need for social approval, and a manifest as public declarations of agreement despite private disagreement
Informational: Reflects a desire to be accurate, arises when the correct answer is ambiguous.
Memory distortions: information suggested by anther person becoming over time part of an episodic memory. People can only remember seeing information which they only heard from another eyewitness.
Gabbert, Memon & Allan 2003
Participants watched the same mock crime event from different eyewitness perspectives. Found that a significant proportion 71% of participants who had discussed the event reported at least one or two erroneous detail acquired during the discussion of their partner. No age related differences (18-30).
This may be possible social and cognitive mechanisms underlying the distortions of memory due to conformity.
Low ecological validity, due to misleading PEI was controlled, type of information imparted.
Hope 2008
We are more likely to conform to our friends than a stranger, which makes us think our memory must be adaptive
Principe & Ceci 2002
Investigated memory conformity in children
Staged a classroom based archeological dig for three groups of preschool children.
3 main conditions;
- target group (witnessed archeological dig and finding being destroyed)
- classmate group (did not witness either of these)
- control
The children were interviewed in either a neural or suggestive manner on three occasions. Results from the fourth interview by a new experimenter revealed that the combination of suggestive interviews and peer exposure led to claims of witnessing the target activities by the classmate group that were comparable to the children who actually did witness these activities.
Misleading questions and employing peer pressure and false claims of actually seeing vs hearing about the target activities were elevated following opportunities with to discuss these activities with peers.
Martin & Gabbert 2011
The visual partner paradigm
3 households depicting busy household scenes. Participants told that their encoding duration would be half their partners.
Perceived encoding manipulation and then presented forced choice questions.
Response from partner was shown, and it was found that perceived encoding duration only affects memory conformity in the shortest encoding duration condition.
Reliance on other peoples memory is dynamically and strategically adjusted according to knowledge of the conditions under which we and other people have acquired different memories.
Memory conformity
Hebert & wheeler 2017
When people discuss their memories they can influence each other’s such that their subsequent individual memory reports become similar.
Paterson & Kemp 2006
People are more suggestible when post event information is encountered directly from a co witness
Meade & Roediger 2002
Participants were more likely to make source- misattribution errors for items of misinformation encountered from a co -witness, reporting that they could remember seeing items that they had in fact only been suggested.
Gabbert 2004: possible that information encountered during face to face interaction is attended to more fully and deemed to be more credible than information from an absent and anonymous source. This might encourage more active and deeper processing of the information, making it more difficult to later discriminate from the originally encoded information.
People may conform to another persons memory due to;
Not wanting to disagree with the other person
Thinking the other person is right
Having a constructed memory based on what the other person said (due to memory distortion or a source attribution).
Source monitoring
Source monitoring refers to the decision by process by which memories are discriminated against one another in order to make attributions about the source of these memories.
Johnsson 1993
The source monitoring framework
Source monitoring is based on the qualities of experience resulting from combinations of perceptual and reflective processes, usually requires relatively differentiated phenomenal experience, and involves attributions varying in deliberateness.
These judgements evaluate information according to flexible criteria and are subject to error and disruption.
Source monitoring decisions can also be made through controlled deliberate strategies such as;
Retrieval of additional information
Supporting memories
Extended reasoning about whether memory is plausible
Source monitoring errors
Being able to recall memory does not guarantee its authenticity
Source monitoring errors can occur when the heuristic judgement process, based in the expected memory characteristics is wrong.
This can occur when the qualities associated with memory from each source are similar.
Lindsey 1990
136 American students
79 colour slides, man steals money and a calculator from an office.
Tape recorded voice accompanied slides with description of events.
Post event information was the narrative
Low discriminability: female voice, participants listened to second description immediately following the slide show. The recording was in the same voice as had accompanied the slides.
High discriminability: male voice. Participants listened to second description 48 hours after the slide show. In a different room and a different voice.
Participants told to disregard information in the second description because it was wrong.
Results: a misinformation effect was only apparent in the ‘low discriminability’ condition because participants found it difficult to discriminate the source of their memories.
Participants in high discriminability condition took advantage of the differences in the memory characteristics accompanying the original information and the PEI.
