Eyewitness Testimony - understanding Flashcards
what are the factors that affect the accuracy of eyewitness testimony
*misleading information
- leading questions
- post-event discussion
- anxiety
what is meant by misleading information
incorrect information given to the eyewitness after the event. It can take different forms such as; leading questions and post event discussion
define leading questions
a question which, because of the way it is phrased, suggests a certain answer
define post event discussion
this occurs when there is more than one witness to an event. Witnesses may discuss what they have seen which may influence the accuracy of each witness’s recall
describe a piece of research into leading questions (without results)
aim - to test the effect of changing a single word in critical questions about the judgement of speed
method - participants were shown a 30 second videotape of 2 cars colliding and then asked several questions about the collision. Group 1 was asked how fast the cars were going when they hit.
For the remaining groups ‘hit’ was replaced with ‘smashed’, ‘collided’, ‘bumped’ or ‘contacted’
These words have different connotations regarding the speed and force of impact.
car crash video
what were the results to the research into leading questions
Results- Those who heard the word ‘hit’ produced an average speed of 34.0mph, for ‘smashed’ 40.8mph, ‘collided’ 39.3mph, ‘bumped’ 38.1mph and contacted 31.8 mph
conclusion - The wording of a question is important to the recall of the events
describe a piece of research into post event discussion (with results)
method- participants in pairs watched a film of the same crime scene but from different angles. This meant that participants could see an element of the event the other could not. Both participants then discussed what they had seen, before individually completing a test of recall.
results - 71% of the participants mistakenly recall aspects of the event they did not see in the video but had picked up in the discussion. The corresponding figure in the control group where there was no discussion was 0%
conclusion discussion with others about an event often leads to new info being added to the memory of the event which a person had not experienced.
define anxiety
a state of emotional and physical arousal. These emotions include having worried thoughts and feelings of tension. Physical changes include increased heart rate and sweating.
How does anxiety effect the accuracy of EWT
anxiety has strong physical effects however it is not clear whether anxiety increases or decreases the accuracy of EWT
Describe a piece of research on the Negative effect of anxiety on EWT (without results)
Johnson and Scott 1976
Method - participants were led to believe they were taking part in a lab study. While seated in a waiting room while participants heard an arguement in the next room. In the low anxiety condition a man walked through the waiting room area with a pen in his hand grease on his hands. In the high anxiety condition participants overheard the same arguement but this time accompanied by breaking glass. A man walked out of the room holding a paper knife covered in blood.
describe the results of the research into the negative effects of anxiety in EWT
results - the participants picked out the man from 50 photos. 49% of the participants were able to identify the man carrying the pen. however, only 33% were able to identify the man carrying the blood covered knife. This could be due to weapn focus
what is weapon focus
the tunnel theory of memory argues that a witness’ attention narrows to focus on the weapon as it is the source of their anxiety.
Describe a piece of research on the Positive effect of anxiety on EWT (without results)
Yuille and Cutshall 1986
Method - conducted a study on a real-life shooting where a store owner shot a thief in a gun shop in Vancover, Canada. There were 21 witnesses with 13 taking part in the study. The interviews were held 4-5 months after the shooting, and compared to the police interview. Accuracy was determined by the nimber of details reported in each account.
The witnesses were also asked to rate their anxiety level at the time using a 7 point scale. then asked if they had had any emotional problems since eg. sleeplessness.
describe the results of the research into the positive effects of anxiety in EWT
results - the witnesses were very accurate in their accounts with little change in accuracy or amount of details after 5 months. Some details were less accurate eg. colour of item/ age/ height/ weight estimates. The participants who reported the highest levels of stress were most accurate ~88% compared to 75% for the less stressed group.
describe Yerkes-Dodson Law
the Yerkes-dodson law posits a relationship between anxiety and performance which looks like and inverted U. This states that performace will increase with stress but only to a certain point where it decreases drastically
Evaluate the theory of weapons focus
The study by Johnson and scott 1976 on weapons focus may test surprise rather than anxiety. Pickel 1998 conducted an experiment using scissors, a handgun, a wallet, or a raw chicken as the handheld item in a hairdressing salon video (where scissors would be low anxiety, low unusualness).
Eyewitness accuracy was significantly poorer in the high unusualness conditions (chicken and handgun).
This suggests that weapon focus effect is due to unusualness rather than anxiety/ threat and therefore tells us nothing specifically about the effects of anxiety on EWT
Evaluate the Yuille and Cutshall 1986 research (weakness)
Field studies lack control
*Researchers usually interview real-life eyewitnesses sometime after the event. *All sorts of things could have happened to the participants in the meantime that the researchers had not control over, for example post event discussion or accounts they may have seen or read in the media, the effect of being interview by the police and so on.
*This is a limitations of field research because it is possible these variables may be responsible for the accuracy of recall.
*The effect of anxiety may be overwhelmed by these other factors, and impossible to assess by the time the participants are interviewed
