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.