Factors affecting the accuracy of eyewitness testimony Flashcards
What is the Eyewitness Testimony? (EWT)
-Ability of people to remember the details of events, which they have observed.
-Accuracy can be affected by lots of factors such as misleading info, leading questions and anxiety.
What are Leading Questions?
A question suggests a certain answer due to the way it is phrased.
What is Misleading Information?
Incorrect information given to eyewitnesses, usually after the event.
Factor 1 Affecting EWT - Leading Questions
-Loftus and Palmer arranged for students to watch fil clips of car accidents and then gave them questions about the accident.
-One critical question - about how fast were the cars going when they (insert different verb) each other?
-Students split into 5 different groups, each received a different question.
-The question contained a verb that changed depending on which group the students were in. e.g. hit, contacted, bumped, collided, smashed.
-Is a leading question as the verb suggests the speed of which the car was going. Mean estimated speed calculated for each participant group.
-Found that verb ‘contacted’ had lowest mean estimated speed.
-Smashed had highest mean estimated speed.
-Can be explained by the response bias explanation, suggests that wording of a question has no effect on memories just how the participants choose to respond.
Loftus and Palmer follow up experiment on Leading Questions
-Participants who had originally received the question that included the verb smashed were interviewed a week later.
- Found that they were much more likely to have seen broken glass than those who heard the verb hit.
- No glass in original clip.
-Can be explained by the substitution explanation - wording of a leading question actually changes the participants memory of the clip.
What is Post Event Discussion?
-Occurs when there is more than one witness to an event.
-Witnesses may discuss what they have seen with co witnesses or other people.
-May influence accuracy of each witnesses recall of the event.
Factor 2 Affecting EWT - Post Event Discussion
-Gabbert et al studied participants in pairs.
-Each participant watched a video of the same crime but filmed from different points of view.
-Participants could see elements in the event that others could not.
- Both participants then discussed what they had seen before individually completing a recall test.
-Found that 71% of participants mistakenly recalled aspects of the event they had not actually seen in the video but had picked up during discussion.
- In a control group with no discussion, 0% recalled inaccurate information.
-Concluded that the witnesses often go along with one another and display memory conformity, to win social approval, or because they believe the other participant within their pair is correct.
Evaluation of Misleading Information - increased awareness
-Has increased our awareness of serious implications of misleading information.
-Police force has now realised that it is important to take extra care when interviewing eyewitnesses to ensure questions do not lead eyewitnesses in any way.
-Strength - research has led to positive improvements in the legal system as more people are aware of the consequences of misleading information on EWT.
Evaluation of Misleading information - real life applications
-Has been used to help eyewitness recall.
-The cognitive interview technique, a technique that requires special training of police officers to ensure that they prevent the effects of misleading information has been developed. Suggests that research can prevent the wrongful conviction of individuals that might occur if leading questions were asked or if post event discussions were allowed.
-Strength- Research has prevented the effects of misleading information in real life.
Evaluation of Misleading information - Artificial Tasks
-Researchers often use artificial tasks to investigate.
-Loftus and Palmer asked participants to watch film clips of car accidents as opposed to real life car crashes. Suggests that results of the study may have been inaccurate due to the physiological state participants were in at time of encoding.
-Weakness - emotions can influence memory, suggesting that lab studies may tell us little about how leading questions affect real eyewitness testimonies.
Evaluation of Misleading information - demand characteristics
- Research is conducted in artificial environments.
-Participants are completing memory studies in labs, may simply be displaying demand characteristics and over or under exaggerating the effects of misleading information.
-Weakness - results will be invalid and effects of misleading information may be stronger than or not as strong as what research suggests.
What is Anxiety?
-A state of emotional and physical arousal.
-Has strong emotional and physical effects.
-Unclear whether these effects make eyewitness recall better or worse.
Factor 3a Affecting EWT - Anxiety has a negative effect on recall
-Recall is worse due to anxiety.
-Johnson and Scott investigated this.
-Participants believed they were going to take part in a lab study.
-In condition 1 - participants heard an argument in the next room before a man holding a pen with grease on his hands emerged from the room. (low anxiety condition).
-In condition 2 - Participants also heard an arguments in the next room but this time a pan emerged holding a paper knife covered in blood. (high anxiety condition).
-Found that when participants were asked to pick out the man from a set of 50 photos, 49% in the low anxiety condition were able to identify him whereas only 33% in the high anxiety condition could.
-Tunnel theory suggests that a witness’ attention narrows to focus on a weapon as it is a source of anxiety.
Factor 3b affecting EWT - Anxiety has a positive effect on recall
-Fight or flight response is triggered which increases alertness and improves memory for the event as we become aware of cues.
-Yullie and Cutshall investigated this.
-Interviewed eyewitnesses of a real shooting in a gun shop in Canada.
- Shop owner shot a thief dead.
-21 witnesses - 13 agreed to take part in study
-Interviews were held 4-5 months after the incident and these were compared to the original police interviews made at time of shooting.
-Accuracy was determined by the number of details reported in each account.
-Witnesses asked to rate how stressed they had felt at time of incident using a 7 point scale and asked if they had experienced any emotional problems since the incident.
-Witnesses accurate in their accounts and little change in amount of accuracy after 5 months
-Participants who reported highest levels of stress were most accurate(88% to 75%. Suggests that the fight or flight response created arousal, leading to better recall.
Yerkes and Davidson & Deffenbacher theory about the effect of anxiety on EWT
-Yerkes and Davidson suggested that the relationship between emotional arousal and performance looks like in inserted U.
-Deffenbacher applied this hypothesis to EWT.
-Lower anxiety produces lower recall accuracy.
-Memory becomes more accurate as the level of anxiety increases up to the optimal level of anxiety.
-If an eyewitness experiences and more stress then their recall declines drastically.
