Factors affecting eye witness testimony Flashcards
What are schemas?
Memories are not accurate snapshots of events, They are reconstructed by schemas which are ready made expectations based on previous experiences. We use them to make sense of the world by filling in the gaps in our knowledge.
What are leading questions?
A leading question is a question which prompts the respondent to answer in a particular way.
Misleading information EXPERIMENT 1 - Loftus and Palmer
Aim - to investigate the accuracy of memory after witnessing a car accident.
Procedure - 45 students shown 7 films of car accidents and had to complete a questionnaire after each one. There was one critical question - ‘How fast were the cars going when they hit each other’. One group had this and other 4 groups had verb either smashed, collided, bumped or contacted.
Results - verb smashed gave higher speed (41) and contacted gave lowest (30)
Conclusion - EWT is inaccurate and therefore unreliable as form of questioning can affect the answer.
Why did Lofts and Palmer do a second experiment?
Experiment 1 didn’t test LTM as EWT usually happens hours or days later rather than straight after. She also wanted to test response bias and substitution explanation.
Misleading information - Loftus and Palmer EXPERIMENT 2 (broken glass)
Aim - to see if ppts estimates of the speed cars could be influenced by misleading questions.
Procedure - 150 ppts shown clip of car accident that didn’t have any broken glass. They were again asked how fast the car was going with either the verb smashed hit or the control. A week later they were asked if they saw any broken glass.
Results - more people reported seeing broken glass with verb smashed - 32%
Conclusion - eye witnesses are unreliable and can have false memories as leading questions can reconstruct them.
Loftus and Palmer EXPERIMENT 1 evaluation
+ reliable
+ internal validity
- bad sample - 45 students
- poor ecological validity
- unethical
- poor application to real life
Loftus and Palmer EXPERIMENT 2 evaluation
+ good sample - 150 ppts
+reliable
+ internal validity
+ good real life application
- poor ecological validity
- unethical
What is post event discussion?
Post event discussion occurs when there is more than one witness to an event. Witnesses may discuss what they have seen with other co-witnesses and influence the recall of the event.
Research into post event discussion - GABBERT
Aim - to investigate the effect of post event discussion on the accuracy of EWT
Method - 60 younger and older ppts. they were put into two groups either individually or in a pair ppts watched video of a girl stealing money from a wallet but from 2 different perspectives where only one group could see the crime. the co witness group discussed the crime and everyone completed a questionnaire.
Results - 71% of co witness group recalled information they hadn’t actually seen and 60% said she was guilty when they hadn’t seen the crime.
Conclusion - this highlights the issue of post event discussion and how it affects the accuracy of EWT.
Research into post event discussion GABBERT EVALUATION
Strengths
- good sample - 60 students and 60 older adults
- real life application - useful for police that eye witnesses should not speak to each other before interviews.
- reliable - easy to repeat.
Weaknesses
- ethics - deception as they were told they were watching the same video
- possible demand characteristics
- lacks ecological validity - doesn’t hold the same emotion or consequences of a real crime.
Research into anxiety - Weapon Focus Study - JOHNSON AND SCOTT (LOFTUS)
Aim - to investigate the effect of anxiety on EWT.
Method - ppts sat outside of a lab where they think they are hearing genuine exchanges. CONDITION 1 - hear a friendly discussion about equipment failure and see a man walk out with greasy hands holding a pen. CONDITION 2 - hear a hostile discussion with the sound of breaking glass and overturned furniture and see a man holding a knife covered in blood.
Ppts were then given 50 photos and asked to identify the man who came out the lab
Results - ppts who had witnessed man with pen were more accurate (49%) than ppts who saw man with knife (33%)
Conclusion - anxiety caused by knife took away attention of face and therefore effects EWT.
What is the Yerkes-Dodson Law
Shows the relationship between emotional arousal and performance represents an inverted u. It explains why some research shows a negative relationship between anxiety and EWT whilst others show a positive one.
CASE STUDY - Yuille and Cutshall - anxiety increases accuracy of EWT
Used witnesses to a real crime involving a gun shooting outside a gun shop in Canada where a thief stole guns and money was then shot 6 times and died. The police interviewed witnesses and 13 were interviewed again five months later.
Recall was found to be accurate even after a long time and two misleading questions had no effect on recall accuracy.
Pickel - challenges the idea that anxiety affects EWT ( surprise)
Pickel arranged for ppts to watch a thief enter a hair salon carrying either scissors ( high threat low surprise), a handgun ( high threat high surprise), a wallet (low threat low surprise) or a whole raw chicken (low threat high surprise)
Identification of the thief was least accurate in the high surprise conditions rather than the high threat conditions.
Valentine and Mesout - anxiety decreases accuracy of EWT
Investigated the memory recall of visitors in the London Dungeons. Whilst walking through the maze, ppts wore a heart monitor to measure anxiety. They were scared by a target person who they had to describe and recall information n once they had left.
Participants in a high anxiety state reported fewer correct descriptions, gave more incorrect details and made fewer correct identifications from a lineup.
