Lecture 2: Eyewitness Testimony and Memory Flashcards
What are the 3 stages of memory?
- encoding: gathering info and putting it in a form that can be held in memory
- storage: holding encoded info in the brain over time
- retrieval: accessing and pulling out the stored info at a later time
Do our brains objectively record data?
- No, memory is made up of subjective interpretations—some info is more salient than others
- Old information has more influence than new
- Belief perseverance
- Memory traces fade over time
- It is surprisingly easy to distort and/or create memories
- Memory is strongly influenced by our views, attitudes and beliefs at the time of recall
- Sensory input is influenced by expectation
- Psychologists have difficulty telling the difference between real and implanted memories
What are heuristics and cognitive biases?
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Heuristics are shortcuts, simplified processing
- Filling in the blanks w/ pre-existing knowledge
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Cognitive biases are mental errors
- Often caused by heuristics
What 4 criteria are jurors given for evaluating eyewitness testimony?
- (1) The reliability of the witness
- e.g. Was the eyewitness’s ability to observe the event impaired?
- (2) The circumstances under which the observation was made
- e.g. How good was the visibility? What was the duration of the observation?
- (3) The description of the observation given
- e.g. How specific was it? Did the eyewitness express certainty?
- (4) The circumstances of the procedure used to obtain an identification
- e.g. How much time had elapsed between the observation and identification?
- Was the lineup procedure fair?
Is there any correlation between eyewitness confidence and accuracy?
- There is a very weak correlation (+0.10) between confidence and accuracy—might not be an actual correlation at all
- Jurors tend to not believe witnesses whose memory for trivial details is poor, but these are actually usually the best (most accurate) witnesses
- Why? The more details remembered about the scene, the less details remembered about the face + victim
- Discussion or questioning about events can alter or add to memory
How do we distinguish between real and suggested memories?
Subtle differences:
- Actual memories tend to include more sensory details
- Suggested memories include greater references to cognitive processes
Real and suggested memories are often indistinguishable b/c:
- Suggested memories are retrieved just as quickly and w/ as much confidence as real memories
- Equally likely to be maintained following contradictory info
Who is susceptible to misinformation and why?
- The relationship is complex—the most susceptible were those with either the best or the worst memory abilities
- Why? The incorporation of misinformation into memory requires two opposite memory demands:
- 1) Forgetting the original information → bad memory
- 2) Remembering the suggested → good memory; overconfident
What causes misinformation to be integrated into memory?
- The act of recollection itself
- Specifically? Encouraging the remembering of misinformation reduces access to the original info
- Which happens a lot in the legal process when you have to go to the police several times, have to talk to lawyers, etc.
- Repetition also increases your confidence
What is the cross-race effect (or “own-race bias”)?
- When it’s harder for people to recognize the faces of people outside their own racial group vs. w/in their own racial group
- Maybe b/c we encode features of people from other races more superficially
- Or b/c we have more experience + contact w/ people our own race → develop better rules for making useful distinctions between faces
- But our ability to recognize faces from other groups increases w/ increased contact
Explain the Morgan et al. (2004) study on effects of stress on memory.
- Found that the rate of correct identifications (after a mock interrogation) was significantly higher for participants in the low stress vs. high condition
- High stress condition produced significantly more false positives
- Further studies have shown that high stress impairs memory
What is the weapon focus effect?
- If eyewitnesses see a perpetrator holding a gun or a knife, their ability to recognize the assailant is impaired
- More focus on weapon since it’s more dangerous → less likely to remember details of the assailant
What are the arousal/threat hypothesis and unusual item hypothesis?
- arousal/threat hypothesis → the danger imposed by weapon is an important part of this effect
- unusual item hypothesis → if you see a bank robber holding a goose hostage, your attention would be on the goose, not b/c it’s dangerous but b/c it’s unusual
Explain the Loftus & Palmer (1974) study on the effects of leading questions.
- Ps watched a video of a minor fender bender
- 5 groups of Ps were asked separate Qs:
- How fast were the cars going when they _____ each other?
- Smashed vs. contacted; smashed on average over 10km faster
- Implications for research: Ps remembered the car as going faster depending on the language/verb being used
- Real life implications? Might be harsher sentences if witnesses report the car as going a faster speed, depending on how the police question them, where there shouldn’t be this difference
- Police officers should strive for more open-ended questions
What is the misinformation effect?
- Happens when a person’s recall of episodic memories becomes less accurate because of post-event information
- Depends on an individual’s suggestibility + misattribution
What is the source misattribution hypothesis?
- When info is retained in memory but the source of the memory is forgotten; i.e. confusion as to the source of details
- Attributes information to wrong source
- “Is this something I actually experienced? …or was I told about it?”
What is the misinformation acceptance hypothesis?
- When people guess answers based on what they heard most recently and/or what they think the police or lawyer wants to hear
- And then begin to believe that info
- Especially if authority figures give subtle cues
What is unconscious transference?
- When a face that is familiar from one context is transferred to the scene of a crime
- e.g. Identifying someone who closely resembles the perpetrator or someone else who was near the scene of the crime
Explain the Loftus (1979) study about misleading cues including stop signs and yield signs.
- Ps came in + watched a video:
- A silver car is parked at a yield sign vs. stop sign
- Another car drives up and passes the silver car, turning a corner
- After a few seconds, you hear a crash/shattering glass sound
- Ps do a filler task, then asked Qs
- “Did another car pass the silver car while it was stopped [answer IS yes] at the stop/yield sign?”
- 4 different conditions: stop vs. yield + consistent vs. inconsistent
- Ps do another filler task, then asked whether they had seen certain pictures/stills from the video
- Inconsistent (misinfo effect group): 41% correct identification
- Higher amount of false positives + not recognizing things they actually have seen
- Consistent (control group): 75% correct identification
- Inconsistent (misinfo effect group): 41% correct identification
- Real world application: running a stop sign would carry much heavier penalties than running a yield sign—you would hope police actually go back to the site of the crime to confirm what kind of sign it was
What is retrieval inhibition?
Selectively retrieving only some aspects of a scene “inhibits” recall for other aspects of that same scene
What are hypnotic hypernesia and memory hardening?
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hypnotic hypernesia: People usually recall more information when they are hypnotized than when they are not hypnotized
- But more info isn’t necessarily better info
- memory hardening: Once an event is vividly imagined under hypnosis, a witness may become confident that the memory is true
What are the 4 admissibility guidelines for information obtained under hypnosis?
R v. Clark (1984): admissibility criteria for hypnosis-induced evidence
- (1) The hypnotic interview should be conducted by an independent and qualified professional.
- (2) The hypnotist should only be given minimal information to perform the interview.
- (3) The hypnotist should try his or her best to avoid any leading questions, suggestive body language, or any other potentially biasing interview techniques.
- (4) The interview should be recorded.
These were overturned in 2007 b/c they were found to be insufficient
What are scripts?
Widely held beliefs about sequences of actions that typically occur in particular situations
Explain the Holst & Pezdek (1992) study on the effects of scripts on recall of a crime.
- Ps heard a mock trial of a defendant accused of convenience store robbery
- Elements such as pulling out a gun + demanding money weren’t present
- But Ps ended up recalling these events happening
What are system variables and how can they affect memory?
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System variables: Variables that are part of the Justice System, over which the police and justice system have at least some control
- e.g. procedures used to select members of line-up, the presentation, instruction given to witness, conditions in the interview, interview style
- How people respond to these questions can be controlled by interview style
- Closed or leading questions: “…when the car smashed…”
- vs. Open-ended questions: “What did you see?”
What are estimator variables and how can they affect memory?
- Estimator variables: outside the control of the legal system (e.g. who witnesses a crime, if the victim is a different race than the criminal)
- Their impact on the accuracy of an identification can only be estimated
- e.g. physical and temporal context of the crime (distance, lighting, duration, weather), age + gender (both of suspect + witness themselves), emotional state, witness eyesight
How can perception influence a person’s memory?
- We perceive events selectively and use imagination (familiarity/plausibility) to fill in the gaps
- Central vs. peripheral details; change blindness
How can plausibility and familiarity contribute to misinformation effects?
- Plausibility is the apparent validity of the statement → increases the perceptions that an experience is correct
- Familiarity is having knowledge of the subject → provides additional details about a possible event
- Our plausibility is usually compared against our familiarity; e.g. What does a bank robber look like?
- Even if the robber didn’t have a gun or wasn’t wearing a balaclava, b/c these things are familiar, they’ll seem more plausible to you
Explain the Loftus (1979) study on impact of eyewitnesses for conviction rates.
- Really weak robbery/murder case (insubstantial evidence)
- Conviction rate: 18% under normal circumstances
- Add an eyewitness → Conviction rate jumps to: 72%!
- Discredit the witness → Conviction rate falls to: 68%!
- Basically not statistically different compared to having an eyewitness
Explain the Lindsay, Wells, & Rumpel (1981) study on the influence of confidence of eyewitnesses on jury’s belief.
- Viewing conditions vs. accuracy of witness
- Witnesses were much better at identifying the thief if the conditions were good (75% correct) vs. moderate (50%) or poor (35%)
- However, the confidence levels of all three groups were equivalent (83%)
- For jurors, they believed the witnesses in the poor + moderate conditions at around 60% (conviction rate) and 78% for the good condition
What are 3 reasons why confidence is not a good indicator of accuracy?
- (1) Confidence increases over time; witnesses have to relive the same moment over and over, giving the same story + looking at the same photographs
- (2) post-identification feedback effect: tendency for biased feedback to distort the memory of eyewitnesses
- e.g. If you’re told you identified the right person → thinking you had a better view of the criminal + had paid more attention during the crime
- (3) cognitive dissonance: once you commit yourself to a particular course of action, you will become motivated to justify that course of action
- → once you’ve identified someone, uncertainty will make you uncomfortable
- → increase your level of certainty to reduce dissonance