Eye Witness Testimonys Flashcards
What does EWT refer to
Evidence provide by those recalling an event who were present when the event took pace
What did Bartlett state about the influence of schema
- memory is not like a camera
- memory is reconstructed based on previous experience and expectations
- our existing experiences and expectations form schemas
- schemas override what we actually see
- schemas are individual but also reflect cultural expectations and stereotypes all of which can cause distortions in recall
What can distortions in recall affect in EWT
Cause a miscarriage of justice
2 factors that effect EWT
- misleading information
- anxiety
What is the effect of misleading info on EWT
Refers to info that suggests a particular response which is actually not accurate
2 types of misleading info
- leading questions
- post event discussion
What is a leading question
Questions that increase the likelihood that an individual schemas will influence them to give an inaccurate answer
What is post event discussion
- Inaccurate information can be added to a witnesses memory of an event through something they hear mentioned after an event - post event information
- occurs because of co witnesses discussing what they saw
Who researched the effect of misleading information
Loftus and palmer
Loftus and palmer experiment 1 - effect of leading questions
procedure
- 45 university students were shown 7 video clips of car crashes
- divided it to 5 groups with 9 ptps
- write down their account of what they could recall after each accident
- they where asked the key question how fast were the cars going when they … with each other
- blank was filled with either hit smashed collided bumped or contacted
- ptps estimation of the speed was recorded
Finding
- contacted = 31.8 mph
- hit = 34.0 mph
- bumped = 38.mph
- collided = 39.3 mph
- smashed = 40.8 mph
Conclusion
- demonstrates that the verb used in the question can have an effect on the estimated speed
- supports assumption that leading questions can have an effect on the accuracy of EWT
Loftus and palmer - experiment 2 - research into the effect of post event info
Procedure
- 150 students ptps viewed a video of a car crash
- questions on what they saw
- 50 ptps asked a key question (same as experiment 1 ) with word smashed
- 50 ptps asked key question with with word hit
- 50 ptps not asked key question
- 1 week later they where questioned about their memory pf the even and was asked if they saw any Brocken glass - there wasn’t any
Findings
Answer Smashed Hit Control
Yes 16 7 6
No 34 43 44
Conclusion
- misleading info in the form of post event info can affect the accuracy of recall of EWT
Gabbert et al - research into post event discussion on accurcay of eye witness testimony
Procedure
- ptps watched a video of girl stealing money from a wallet
- ptps tested individually (controlled) or in pairs (co-witness groups)
- ptps in co witness group were told that they had watched the same video but had seen different perspectives of the same crime and only one person witnessed the girl stealing
- co witness groups discussed crime together
- all ptps completed a questionnaire
- tested uni students and older adults
Findings
- 71% of the witnesses in co witness groups recalled info they had not actually seen
-60% said girl was guilty, despite not seeing her commit the crime
- little difference between groups studied
Conclusion
- post event discussion can have a powerful effect on the accuracy on eye witness testimony
What is post event discussion
Discuss what they have seen with other witnesses
Distort their own memory of an event
Post event info
Witnesses receive info about the crime
Which can distort their own memory of crime eg through media and police
Strengths of research into the effect of misleading questions
Importance of research
- Contributed to better understanding of how misleading information affects EWT
- developed better questioning techniques for police when dealing with witnesses
Weaknesses of research into the effect of EWT
Low ecological validity - lab study, artificial tasks cant generalises finding to real world situations
Low population validity - manly studies on students difficult to generalise to wider society however gabbert did study older adults
Ethical issues - psychological harm, ptps deliberate put in distress for the sake of research
What can anxiety cause
- bodily arousal (activates physiological stress response
- heightens attention and focus, so an be beneficial
What is yerkes Dodson law
Dictates that performance increases with physiological or mental arousal but only up to a a point
What happened when arousal becomes to high
Performance decreases
How is yerkes-Dodson law illustrated
Inverted u shape curve which increases and decreases with higher levels of arousal
How are studies on EWT conflicting
Lab studies suggest that anxiety decreases Ed accuracy where as real life studies contradict this
Research into negative effect of anxiety on EWT
Loftus
Procedure
- ptps sat in a waiting room in 2 conditions
- condition 1: ppts overheard a discussion in a laboratory about an equipment failure, a person then emerged from the lab holing a en with grease on his hands
- condition 2: ptps overheard a heated hostile exchange between people n the laboratory, after a series of loud sounds and man emerged from the lab holding a knife and cover in blood
- ptps were then given 50 photos and asked to identify the person who had come out the lab
Findings
- 49% of ptps in condition 1 correctly identified the man
- 33% ptps in conditions 2 correctly identified the man
Conclusion
- anxiety caused by a weapon can divert attention from other important features of a situation as the witness focuses on the weapon
Strengths of Loftus study on the effect of anxiety
Lab study
- Easy to control extraneous variables
- easy to replicate
Weakness of Loftus study on the effect of anxiety
- lack ecological validity, conducted in a lab, artificial, annotate generalise finding to real life
- ethical issues, psychological harm, put in distress
Studies of real life EWT and anxiety
Christianson and huinette
Procedure
- 110 witness of 22 bank robberies were interview 5 months after te robberies
Found
- witness were surprisingly accurate in their recall of the robbers clothing and behaviour, even in those who had been directly treated and subjected to violence
Conclusion
- suggests that anxiety increases and has no effect on EWT
Strengths of real life studies of anxiety and EWT
- high ecological validity, can generalise findings
- beneficial use real witness of real crimes
Weaknesses of real life studies on anxiety and EWT
- hard to replicate
- less control of extraneous variables eg possible post event discussion or post event info
