Chapter 12 Flashcards
Provide statistics that prove the falsifiability of eyewitness testimony
- Only in 5% of cases is DNA evidence available to prove eyewitness testimony wrong
- Only 55% of items about eyewitness testimony was correctly indicated by 160 judges + they minimized the factors causing eyewitness testimony to be inaccurate.
- Only 23% agreed that: “Only in exceptional circumstances should a defendant be convicted of a crime solely on the basis of eyewitness testimony.”
- Judges’ knowledge was the same as undergraduate students + less than that of law students.
- 100% of experts agreed that an eyewitness’s expectations influence their memory
- 95% of experts agreed that info provided after an event can distort eyewitness memory.
- Lay knowledge differed from expert knowledge on one-third of the factors.
Describe Inattentional blindness
Simons and Chabris gorilla study:
-All the participants watched a video, with some counting how many times students threw a ball to each other. At some point, a gorilla suit walks into the camera shot, thumps her chest, and then walks off. 50% of the observers did not notice the “gorilla” at all.
-Inattentional blindness: The failure to perceive the appearance of an unexpected object in the visual environment.
Describe change blindness
- Involves a failure to detect changes in an object (e.g. it has been replaced) + is extremely common.
- Inattentional blindness and change blindness are very similar phenomena.
- More complex processing is typically required to avoid change blindness
We are often wildly optimistic about our own observational powers
Study: Participants who had been forewarned of the changes saw videos of two people having a conversation in a restaurant. With many changes occurring in different videos of the same scene.
Results: None of their participants detected any of the changes.
-Percentage of people claiming they would have noticed changes: 78% for the disappearing scarf; 59% for the changed man; and 46% for the change in colour of the plates.
Why does change blindness blindness happen?
Change blindness blindness: Individuals’ exaggerated belief that they can detect visual changes and so avoid change blindness .
1) We generally think we are processing the entire visual scene reasonably thoroughly + can detect visual changes.
2) We are much better at detecting changes in objects we have previously looked at directly + underestimate the importance of fixating objects when told to remember their changes
3) Greater change blindness blindness when we detect object changes rapidly/effortlessly rather than slowly/effortfully.
4) Also greater when we believe we’re great at detecting changes.
How do our expectations influence eyewitness testimony?
-Memory is often influenced expectations–>confirmation bias e.g supporters of two teams often have opposing memories of crucial moments in the game.
Confirmation bias: Distortions of memory caused by the influence of expectations concerning what is likely to have happened.
-Study: football game between two American universities
A film of the game was shown to students + had to detect infringements of the rules.
-Results: detected 2x as many rule infringements by opposing team than own team.
This is an example of confirmation bias
- Another study: Swedish + immigrant students saw a videotaped robbery in which the perpetrator seriously wounded a cashier with a knife.
- Then, eyewitnesses were shown photographs of eight men (four Swedes + four immigrants).
- Results: Both immigrant and Swedish eyewitnesses were 2x likely to select an innocent immigrant as an innocent Swede.
- Overrepresentation of immigrants in crime influenced participants’ expectations about the likely ethnicity of the perpetrator
Describe Bartlett’s schema theory to explain why expectations influence our memories
- We possess numerous schemas stored in LT memory which lead us to form certain expectations.
- According to the schema theory, recall involves a process in which all relevant info is used to reconstruct the details of an event based on “what must have been true.”
- Recall of a bank robbery is influenced by the info contained in their bank-robbery schema.
- Recall was better for info relevant to the bank-robbery schema than for irrelevant info. Thus, eyewitnesses used schemas to assist recall.
Describe study where eyewitness memory is distorted to conform to the relevant schemas.
Study: some eyewitnesses saw a robber’s head covered so gender was ambiguous.
Results: Eyewitnesses tended to recall the robber as being male.
-The eyewitnesses tended to misremember gender-inconsistent info–>used their male gender schema to infer that the criminal’s feminine features, clothing, and behaviour were actually ‘masculine’
How does post-event misinformation explain inaccurate memories of eyewitnesses?
-Memories are fragile + easily distorted by what happens after observing the crime.
Study: Participants watched a film about a car accident, described what had happened.
- Asked, “About how fast were the cars going when they hit each other?”
- Others were asked the same question but with the word “hit” replaced by “collided,” “bumped,” “contacted,” or “smashed into,”
- Results: Speed estimates were highest when the word smashed was used, lower with collided, and lower still with bumped, hit, and contacted.
- 32% of those previously asked about speed using the verb “smashed” said they had seen broken glass when asked a week later, in comparison to only 14% of those using the verb “hit”
- Memory can be impaired even when the eyewitnesses were warned about the presence of misleading information very shortly after it had been presented.
- Explicit warnings do not eliminate the negative effects of misinformation on memory but simply reduce it.
- Info acquired between original learning + subsequent memory test can disrupt performance on that test (retroactive interference)
Can eyewitness memory also be distorted by proactive interference (learning occurring prior to observing the critical event)?
Study: Participants saw a video of a museum burglary. On the previous day they listened to a narrative thematically similar (a palace burglary) or thematically dissimilar (a school field-trip to a palace) to the video.
- Results: Made many more errors when recalling info from the video when the narrative was thematically similar than dissimilar.
- Inaccurate eyewitness recall can depend on retroactive and proactive
Are there individual differences in susceptibility to misinformation effects?
- Eyewitnesses with higher intelligence + greater working memory are better at resisting misinformation.
- More intelligent individuals have generally superior memories to those of less intelligence. Personality characteristics associated with resisting misinformation include
- Being high in fear of negative evaluation + low in cooperativeness and reward dependence->more resistant to misinformation
- Memory distortions are more common for peripheral or minor details than for central details.
- Also when participants are informed that others remembered the events differently, memories subsequently became severely distorted
How does misleading info distort what eyewitnesses report?
-Source misattribution–>A memory probe (e.g. a question) activates memory traces overlapping with it in terms of the info they contain.
- Most likely when the memories from one source resemble those from a second source.
- The eyewitness decides on the probable source of any activated memory on the basis of the info it contains.
- Eyewitnesses “accept” misleading info presented to them after an event + regard it as forming part of their memory for that event.
- Accepting post-event info in this way becomes more common as the time since the event increases.
- Why? b/c it is generally adaptive to update + change existing memory traces by incorporating new relevant info into them.
Study: eyewitnesses saw a pedestrian accident involving a car stopping at either a stop sign or a yield sign. Two days later, asked questions about the incident, one of which biased them away from what had actually happened.
Their memory was tested by asking them which sign they had seen
Results: If participants remembered the correct response but did not say to please the experimenter–>bias could be removed by offering a high enough pay-off for making a correct response.
In spite of monetary incentives, between 70%-85% of those tested selected the wrong response. This suggests (but does not prove) that the original memory trace had been altered. -The biasing effect disappeared when participants were questioned systematically starting with earlier incidents and working through to later ones.
What can be done to reduce the negative impact of misleading post-event info on eyewitness memory?
Early opportunity to recall the details of a witnessed crime would strengthen the relevant memory traces by protecting them from distortion by misleading info.
Those who completed a self-administered interview providing all the details of the crime before being given misinformation followed by event recall–>remembered many more correct details at this one-week recall + more resistant to the misinformation.
How does eyewitness confidence influence testimony?
- Eyewitness confidence depends on the amount of info retrieved, familiar knowledge + expectations.
- Jurors are often influenced by how confident the eyewitness seems to be
- Confidence is often moderately associated with accuracy.
-Study: distinguished between choosers (eyewitness making a positive identification) and non-choosers (those not making a positive identification).
No correlation or association between confidence + accuracy among nonchoosers.
However, choosers’ confidence predicted their accuracy to a moderate extent.
The strength of the relationship between confidence + accuracy is variable
What are the two factors that reduce the association between confidence and accuracy?
1) Confirming feedback: involves telling eyewitnesses that they have identified the suspect–> increased
- Results: eyewitnesses’ confidence in identification accuracy much more when it was incorrect than when it was correct.
- If eyewitnesses are told by police that their identification was correct–>higher confidence even when wrong
2) The Dud effect: An eyewitness’s increased confidence in his/her mistaken when the lineup includes individuals very dissimilar to the culprit.
-Study: In one experiment, eyewitnesses observed a mock crime followed by a lineup of 2 people resembling the culprit
-In another, the lineup had the same to 2 people + 4 people very dissimilar to the culprit (duds)
Results: Eyewitnesses were much more confident in the correctness of their choice when duds were present, even when incorrect
-The presence of duds increased the perceived similarity of the other members to the culprit.
Does high emotion impair facial/detail recognition?
- 82% of defence lawyers and 32% of prosecution lawyers believed that high emotion impairs facial recognition.
- Face recognition was correct on average 54% of the time in low anxiety or stress conditions, compared to 42% in high anxiety or stress conditions–>Heightened anxiety has a negative impact on identification accuracy.
- Recall of culprit details, crime scene details, and the actions of the central characters was correct 64% of the time in the low anxiety conditions compared to 52% in the high anxiety conditions.
- Physiological arousal had no effect on the recall of central or peripheral details.
- In contrast, medium emotional arousal improved recall of central + peripheral details
- whereas high emotional arousal impaired recall of central details.
Does weapon focus influence recall?
Weapon focus: The finding that eyewitnesses have poor memory for details of a crime event because they focus their attention on the culprit’s weapon.
Overall, there was a moderate effect on eyewitness memory of weapon focus.
Study: each participant waited outside a lab.
- In the “no weapon” condition–>overheard a harmless conversation about equipment failure in the experimental room, after which someone emerged holding a pen
- In the “weapon” condition–>heard a hostile exchange between two people, ending with broken bottles, chairs crashing, + someone leaving holding a letter opener covered in blood.
- Given an album containing 50 photographs and asked if the person was in there
- Results: 49% correct identification in “no weapon” vs. 33% in “weapon” condition.
-Eyewitnesses tend to focus on the weapon at the expense of other aspects of the situation.
People often attend to stimuli that are unexpected in a situation–>impairs their memory for other stimuli.
- Study: participants watched one of two sequences: 1 A person pointing a gun at a cashier. 2 A person holding a check to the cashier.
- They looked more at the gun than they did at the check so memory for unrelated details less vivid
- A stronger weapon focus effect when a female criminal was carrying a knife + when a male criminal was carrying a knitting needle because it is more unexpected
Describe Easterbrook’s hypothesis.
- Stress or anxiety causes a narrowing of attention on central or important stimuli + reduction in the recall of peripheral details.
- Memory for peripheral details was much worse with highly stressful pictures than with moderately stressful ones
Is eyewitness testimony of older adults less accurate than that of young ones?
60-to 80-year-old people are more likely than younger adults to choose someone from a lineup even when the culprit was not present.
- Older people are more strongly influenced than younger adults by misleading suggestions.
- Study: presented misleading info to younger + older adults.
- Results: Older adults had a 43% chance of producing false memories vs.only 4% for younger ones.
- Another study: showed a video to younger + older adults, who later completed a questionnaire that misleadingly referred to events not shown on the video.
- Results: The older adults were more likely to produce false memories triggered by the misleading suggestions.
-older adults are more confident about the correctness of their false memories than younger ones.
What are the reasons why older adults produce more false memories + are more confident about them?
Reason 1: Schemas
Study: examined the effects of the bank-robbery script on recall + recognition.
Results: Older eyewitnesses relied on the bank-robbery script/schema when details of the actual robbery did not correspond to it
Reason 2: Own-age bias
-Differences in the accuracy of memory also depend on the characteristics of the culprit.
-Study: presented crime videos + then asked eyewitnesses to identify the culprit.
Results: They found an own-age bias–> both groups being more accurate at identification when the culprit was of a similar age to themselves.
-Own-age bias is due to the greater exposure most people have to people of their own age whereas teachers who spend lots of time with kids did not have an own-age bias
Describe prosopagnosia and related studies
Prosopagnosia: A condition, also known as face-blindness, in which there is extremely poor face recognition combined with reasonable ability to recognize other objects.
-They can recognize most objects reasonably well in spite of their enormous difficulties with faces.
Study: Participants were presented with a target face taken from a CCTV video + 10 photographs
-Had to select the matching face or to indicate that the target face was not present in the array.
-Results: Performance was disappointingly poor.
When the target face was present in the array, it was selected only 65% of the time.
-When it was NOT present, 35% of participants nevertheless identified someone even when they watched a clip of the video a 2nd time
-We have much greater problems with unfamiliar faces than familiar ones
Study: Participants were presented with 40 photographs + had to sort them into a separate pile for each person shown.
-For Dutch participants, the faces were familiar + their performance was almost perfect
-For British participants, they thought 7½ different individuals were shown across the 40 photographs
-Performance would be even worse if memorization was involved.
-In this case, a single photograph of an unfamiliar face conveys limited info–>passport photographs have limited value.
Average face-recognition performance is poor but very variable. Why?
Study: participants had to decide on each trial whether two faces showed the same person.
Results: Face-recognition performance on the same unfamiliar faces often fluctuated considerably from day to day–> lack of consistency in performance
- Another study: Participants were presented with photos of people undisguised or wearing accessories
- Photos were repeatedly presented until it was consistently recognized + the person’s name given correctly.
- Then presented with photos of the same people with various combos of disguise and had to detect + name the target individuals.
- Results: The effect of disguise was dramatic. Every time an item of disguise was added or removed the probability of correct recognition decreased.
- Clark Kent effect—Adding or removing glasses between the initial encoding + the subsequent recognition memory test impaired performance. Same thing with a wig
- Why? Because face recognition involves holistic processing, thus glasses influence how other parts of the face are processed.
Describe unconscious transference
Unconscious transference: The tendency of eyewitnesses to misidentify a familiar (but innocent) face as belonging to the culprit.
-Eyewitnesses are sometimes better at remembering faces than the precise circumstances in which saw the face.
- Study: A video of a crime in a supermarket with 2 innocent bystanders.
- Eyewitnesses inspected a lineup from which the criminal was absent.
- Results: 23% of the eyewitnesses selected the innocent bystander who had passed behind the boxes + 29% selected the innocent bystander who had been in the produce aisle.
-A psychologist took part in a live television discussion on the unreliability of eyewitness testimony. Sometime later, he was picked up by the police, and placed in a lineup. A very distraught woman identified him + charged with rape
It turned out that the woman had been raped while watching the program.
Describe verbal overshadowing
-Verbal overshadowing: The reduction in recognition memory for faces that often occurs when eyewitnesses provide verbal descriptions of those faces before the recognition-memory test.
- Study: Eyewitnesses watched a film of a crime. Then either did an unrelated task or gave a verbal report of the criminal’s appearance
- Results: The verbal report group performed worse than the other eyewitnesses
- Sometimes describing faces verbally enhances face-recognition memory.
- Beneficial when participants engaged in subvocal verbal processing during the initial face presentation b/c it directed attention to important visual features of faces.
- Harmful when producing verbal descriptions after face presentation b/c it increased participants’ attention to general semantic info about the faces, but reduced focus on the subtle perceptual + spatial info
Describe Cross-race effect
Cross-race effect: The finding that recognition memory for same-race faces is generally more accurate than for cross-race faces.
-Eyewitnesses having the most experience with members of another race have a smaller cross-
race effect than those with less experience
-The faces of ingroup members are processed more thoroughly than those of outgroup members–>recognition should be better for ingroup faces
Study: The cross-race effect disappeared when white, middle-class American students saw photographs of white men in impoverished contexts (e.g. ramshackle housing). -This happened because these white faces were not regarded as belonging to the students’ ingroup.
Describe why the cross-race effect depends importantly on perceptual processes?
Study: British + Egyptian participants were presented with a target face + an array of 10 faces and had to identify the target in the array
- Results: Even though perception rather than memory was involved, there was evidence of the other-face effect.
- When the target face was present, correct identification occurred on 70% of trials with same-race faces vs. 64% for other-race faces.
- When the target face was absent, a face in the array was mistakenly identified as the target on 34% of trials with same-race faces vs. 47% for other-race faces.
- Photographs of the same face often differ considerably from each other + this causes major problems in face recognition. These problems are much greater with unfamiliar faces
- Solution: We can enhance face recognition by combining info from multiple photos of the same face to create an average which leads to faster recognition
Provide evidence that the performance of eyewitnesses is rather fallible in lineup selections
- 640 eyewitnesses who tried to identify suspects in 314 real lineups
- Only 40% of witnesses identified the suspect, 20% identified a nonsuspect, + the remaining 40% failed to make an identification.
-Lineups can be simultaneous (the eyewitness sees everyone at the same time) or sequential (the eyewitness sees only one person at a time).
- When the culprit was present, they were selected more often with simultaneous lineups than sequential ones.
- When the culprit was absent, eyewitnesses mistakenly selected someone with simultaneous lineups more often than with sequential ones.
- Sequential lineups are more diagnostic (better at distinguishing between guilty + innocent)
How to reduce minimizing identification errors in line-ups?
1) By explicitly providing eyewitnesses with a not-sure option.
2) Warn eyewitnesses that the culprit may not be in the line-up–>reduced mistaken identification rates in culprit-absent lineups by 42%, while reducing accurate identification rates in culprit-present lineups by only 2%.
What is a cognitive interview? Why is it effective?
-Historically, the police would ask closed-ended questions, interrupt eyewitnesses and disrupt their concentration + ask questions in a predetermined order.
- Cognitive interview which was originally devised by Geiselman et al. based on four general retrieval rules:
1) Mental reinstatement of the environment + any personal contact experienced during the crime.
2) Encouraging the reporting of every detail regardless of how peripheral it might seem
3) Describing the incident in several different orders.
4) Reporting the incident from different viewpoints including those of other participants or witnesses. - It is effective b/c it makes direct use of our knowledge of human memory.
- The first two rules are based on the encoding specificity principle–>eyewitnesses will remember most when there is maximal overlap between the crime context + the recall context
- The third + fourth rules are based on the assumption that memory traces are complex–>info about a crime can be retrieved using various routes
Enhanced cognitive interview–> all four rules + it also requires investigators to minimize distractions, to persuade the eyewitness to speak slowly, to reduce anxiety, + to review the eyewitness’s descriptions.
Describe the pros and cons of cognitive interview
- The number of details correctly recalled was much greater than with the standard interview.
- But benefits reduced when the situation was highly arousing, or when there was a long interval of time had passed
- There is a small (but significant) increase in recall of incorrect details vs. the standard interview.
- But if they close their eyes recall is enhanced b/c It reduced cognitive load on the eyewitness + also reduced distraction.
- It does not reduce the effects of misleading info on memory when they are presented before, but it does reduce the effects when info is presented after the interview
- Mental reinstatement of the situation + reporting all the details both enhanced recall, however, altering the eyewitness’s perspective + changing the order in which the info was recalled were ineffective.
- Requiring eyewitnesses to recall info in a backward temporal order actually reduced the number of correct details recalled + increased recall errors.
- Context has less effect on recognition memory than on recall + so does not improve face recognition from photographs or lineups
What are the problems with lab studies?
In labs, the event in question is observed by eyewitnesses, not the victim, it is obviously less stressful, and the event is observed from a single perspective in a passive fashion, and typically spend much less time observing the criminal. Plus, the consequences of making a mistaken identification in the lab is trivial
Does the presentation of expert testimony improve the accuracy of jurors’ decisions?
Courts should admit eyewitness expert testimony to correct the misperceptions about the reliability of eyewitness identifications. However, some argue that the experts would not be any better at detecting witness inaccuracy than uninformed jurors.
- Study: There were three versions of the case in which the evidence against the defendant was very strong, moderately strong, or weak.
- In all three versions, the prosecution case depended in part on eyewitness testimony from a man observing the crime from a bedroom window.
- Results: The presence of expert testimony produced a relatively large reduction in guilty verdicts regardless of the strength of the case.
- Even when the overall case was very strong, expert testimony reduced guilty verdicts from 74% to 59%.
Exposing mock jurors to expert testimony made them focus too much on possible inaccuracies at the expense of the otherwise strong evidence against the defendant.
Sensitivity–>ability to weigh up accurately the quality of evidence provided by an eyewitness.
Skepticism–> tendency to disbelieve an eyewitness regardless of the quality of their evidence.
However, the main effect of expert evidence is to increase jurors’ skepticism, not sensitivity
Do lab findings show large + systematic effects on the accuracy of eyewitness memory?
Study: had eyewitnesses watch an event via slide shows, video films, or live staged events. There were only small differences in the accuracy of culprit identification across these three conditions–> lab conditions do not lead to distortions in the findings obtained.
Another study: made use of a staged robbery involving 2 armed robbers
- In the live condition–>the eyewitnesses were ordered repeatedly to “Stay down.”
- In video condition–> saw the video of the above
- Results: Participants in both conditions exaggerated the duration of the event, + the patterns of memory performance were similar.
- However, the video condition recalled more info than those in the live condition.
- Thus, witnesses to real-life events are more inaccurate in their descriptions
- Lab conditions provide an underestimate of eyewitnesses’ memory deficiencies for real-life events–> thus, lab research provides evidence of genuine relevance to the legal system.
Another study: Eyewitnesses observed a staged theft live or via video.
- Identification accuracy of the culprit was comparable in the two conditions.
- However, the live condition reported more stress + arousal.
- Identification accuracy was higher when the eyewitness was exposed to the culprit for a relatively long period of time + when the interval of time between the crime and questioning was short.
Does expert testimony improve juror judgement?
Study: The witnessing + identification conditions were good or poor.
In the poor condition–>the robber was disguised, his gun was not hidden + identification took place 14 days after the robbery, + the lineup instructions were suggestive
In the good condition–>the robber was not disguised, his gun was hidden + identification took place 2 days after the robbery, + the lineup instructions were not suggestive.
- Results: quality of the witnessing + identification conditions had a significant impact on jurors’ judgments as to the accuracy of the witness’s identification
- when expert testimony was not presented–>the conditions had practically no effect
- When expert testimony was presented–>verdict was much more influenced by the witnessing + identification conditions
- Thus, jurors not exposed to eyewitness expert testimony were fairly insensitive to the quality of the witnessing + identification conditions to which the eyewitness was exposed.
Another study: Eyewitnesses view a simulated crime + their subsequent testimony about that crime is videotaped.
Jurors then view the videotapes + judge the witness’s accuracy.
-After that, half of the jurors hear expert testimony, the other half do not.
-Results: Jurors who have heard the expert testimony make more accurate decisions than those who have not.
-In conclusion, the presentation of this evidence to jurors by eyewitness experts needs to be done very carefully.
