accuracy of eye witness testimony Flashcards
what is eye witness testimony?
evidence supplied by people who witness a specific event or crime, relying on their memory
what are the 2 factors that can affect eye witness testimony?
● misleading information
● anxiety
what is misleading information?
● incorrect information given to eyewitness usually after event
● for example, leading questions and post event discussions
what is a leading question?
a question which, because of the way it’s phrased, suggests a certain answer
explain the key research of loftus and palmer
● students shown video clips of road traffic accident
● then students were split into 5 different groups
● all participants were asked ‘how fast were the cars going when they (smashed / contacted / another verb) into each other
● participants recalled that the mean estimate of speed was higher when verb smashed was used
● whereas, mean estimate of speed was lower when verb contacted was used
what did loftus and palmers research conclude about leading questions?
● leading questions can clearly influence people’s perception of speed
● as those who heard more emotive verbs (smashed) will give higher speed estimates than less emotive verbs like (contacted)
why do leading questions affect EWT?
● response bias
● substitution
what is the response bias explanation for leading questions affecting EWT?
● wording of a question has no actual effect on a person’s memory
● but instead just influences how they decide to answer
what is the substitution explanation for leading questions affecting EWT?
wording of question actually does change a person’s memory of an event
explain the loftus and palmer follow up study
● students watched short video of car accident
● group 1 asked how fast cars going when they hit (low impact verb) each other
● group 2 asked how fast cars going when they smashed (high impact verb) into each other
● group 3 was not asked about speed of vehicle
● followed up a week later and asked - ‘did you see any broken glass?’ (there wasn’t any)
what were the findings of loftus and palmers follow up study?
● critical verb in question altered memory of incident (substitution)
● participants genuinely believed that there was broken glass in the smashed condition
what is post-event discussion?
● occurs when there is more than one witness to an event
● those who have observed event will discuss what has happened with other co-witnesses
why does post-event discussion affect EWT?
● memory contamination
● memory conformity
what is memory contamination?
when co-witnesses discuss an event, they mix information they get from others with their own memories
what is memory conformity?
● people simply go along with what each other are recalling simply for social approval
● or because they believe other person must have the right info
what is anxiety?
a state of emotional and physical arousal to a stressful situation
why does anxiety have a negative effect on recall?
● creates physiological arousal in body
● which prevents us paying attention to important cues / details in environment
what is the supporting research that suggests anxiety has a negative effect on recall?
● johnson and scott
● p’s thought - taking part in lab study - put in ‘waiting room’ - disagreement next door
● condition 1 (low anxiety group) - heard quiet disagreement - saw man leave room holding pen with grease on his hands
● condition 2 (high anxiety group) - heard heated argument - saw man leave room holding knife with blood on his hands
● had to later identify man from set of 50 photos
what were the findings and conclusion of johnson and scott’s research?
● 49% in low anxiety group were accurate
● 33% in high anxiety group were accurate
● conclusion: supports ‘the weapon effect’ in that witnesses attention is drawn towards weapon as it is a source of danger and anxiety and therefore will not take in any other info of scene
why does anxiety have positive effect on recall?
● stress of seeing crime / accident triggers fight-or-flight response which increases alertness
● so we become more aware of surroundings including cues/details of situation
what is the supporting research that anxiety has positive effect on recall?
● yuille and cutshall
● studied real life robbery / shooting in gun shop where owner shot thief dead
● witnesses interviewed 5 months later and compared recall to original account given to police at time of incident
● also asked to rate stress levels at time of incident and if they had experienced any emotional problems since
what were the findings and conclusion of yuille and cutshall’s research?
● witnesses were very accurate in their accounts with little changes in accuracy over 5 months (some minor details = less accurate)
● found that those who reported highest levels of stress were most accurate in recall = 88% in most stressed and 75% for less stressed
● conclusion: anxiety can have positive impact on recall of events
how can we explain the contradictory finding of anxiety both having a positive and negative effect on recall?
the inverted U
what does the inverted U suggest?
● anxiety increases accuracy of EWT (due to increasing attention) up to optimal point
● after this, strong anxiety impairs accuracy of EWT
