Eyewitness testimony accuracy Flashcards
eye witness testimony
an account given by people of an event they have witnessed and can be defined as the ability of people to remember the detail of events such as accidents and crimes
What can the accuracy of EWT be affected by?
misleading information including leading questions and post event discussion
Misleading information
Incorrect information given to the eyewitness usually after the event.
Leading questions
A question that suggests to the witness what answer is desired and leads them to give a certain answer. Studied by Loftus and Palmer
Loftus and Palmer (1974)
45 students watched clips of car accidents and were then given questions- one of which was a leading question. (different people were given slightly different questions)
What were the participants asked in Loftus and Palmer 1974
‘How fast were the cars going when they hit each other?’ Other participants were asked the same question with a different verb. ‘smashed’, ‘Bumped’, ‘collided’ and ‘contacted’
What were the results of the Loftus and Palmer (1974) study?
the verb ‘contacted’ resulted in a mean estimate speed of 31.8 mph. the verb ‘smashed’ was 40.5 mph.
Loftus and palmer (1974)second experiment
If leading question changes memory of clip because participants who heard smashed were more likely to see broken glass (there was none).
Loftus and Zanni (1975) procedure
Participants shown video of car accident and asked questions. Asked if they saw ‘a’ broken headlight and 7% said yes, asked if they saw ‘the’ broken headlight and 17% said yes
Loftus and Zanni (1975)
The word ‘the’ was leading as it implied that there was a broken headlight and leading question affected memory
Post-event discussion
when witnesses discuss a crime after it happened
What are the types of post event discussion
Memory contamination and Memory conformity
Memory contamination- PED
Witnesses mix information from other witnesses into their own memory
Memory conformity- PED
Witnesses pick up details from the eyewitness testimonies of other witnesses as they want social approval or believe the other witnesses are right
What research was carried out on the accuracy of Post-event discussion and EWT?
Gabbert et al (2003)
What was the method of Gabbert et al (2003) study?
60 students from University of Aberdeen and 60 adults from community watched a video of a girl stealing money from a wallet and were tested individually (control) or in pairs (co-witness group) and this group were told they watched the same video but they watched different perspectives of the same video. only one in the pair saw the girl steal. participants then discussed the crime together and did a questionnaire
what were the results of the Gabbert et al (2003) study?
71% of witnesses recalled information they hadn’t seen (compared to 0% in control group) and 60% said girl was guilty when they had not seen the crime
What is the conclusion of the Gabbert et al study (2003)?
Highlights issue of post event discussion and the effect of accuracy of EWT and witnesses will absorb information from other witnesses.
What are the strengths of research into effects of misleading information on EWT?
- Mostly well-controlled lab studies and extraneous variables are easy to control making it easier to make a conclusion about misleading information. Studied can easily be replicated to test reliability
- Research into misleading information on the accuracy of EWT has important applications to real life as leading questions can effect witness memory
What are the weaknesses of lab studies into EWT
- watching a video is very different to witnessing it in real time and doesn’t cause anxiety. anxiety increases accuracy
- In real life EWT has serious consequences so participants aren’t as motivated to be accurate
- Risk of demand characteristic and effects validity
Yuille and Cutshall (1986)
13 witnesses of a real crime interviewed 5 months after an event. Two leading questions were asked and recall was accurate with no effect on recall accuracy. Shows EWT more accurate in real life
What is anxiety’s effect on EWT?
Strong emotional and physics effect on eye witnesses and is not clear whether it makes recall better or worse as research supports both
Yerkes and Dodson Law (1908)
The relationship between emotional arousal and performance looks like an inverted U
Deffenbacher (1983)
Lower levels of anxiety produce lower levels of recall accuracy but memory becomes more accurate as the anxiety levels increase. However there comes a point (medium) where the optimal level of anxiety is reached. This is the point of maximum accuracy. If an eyewitness experiences more stress than this, accuracy decreases dramatically.
weapon focus effect
Anxiety levels rise when a weapon is presented and focus shifts from crime to weapon.
Johnson and Scott (1976) procedure
Pps sat outside a lab and heard one of two situations inside and then had to identify a man on the basis of 50 images
What were the two situations in the Johnson and Scott (1976) study?
1) Friendly conversation with a man emerging carrying a pen with grease on his hands (low anxiety condition)
2) An argument with smashing class and overturned furniture followed by a man emerging with a blood stained paper knife (high anxiety condition)
What were the results of Johnson and Scott (1976) study?
Witnesses were 49% accurate with the low anxiety condition and 33% with the high anxiety conditiom
What was the conclusion of the Johnson and Scott (1976) study?
Anxiety generated by the weapon diverted attention away from the face of the man due to weapon focus effect
Christianson and Hubinette (1993)
High anxiety creates more accurate memories. Found enhanced recall when questioning 58 real witnesses to a bank robbery in Sweden. (all victims or bystanders) done 4-15 months after robberies and all witnesses showed good memory and victims (most anxious) had best accuracy.
Weaknesses of Anxiety as a factor effecting EWT
- Weapon focus not caused by anxiety. Pickle (1998) suggests poor accuracy may be due to surprise instead of anxiety
- Field studies lack control and confounding variables may have had an affect.
- Ethical issues when carrying out studies on anxiety
- Yerkes Dodson law is too simplistic as anxiety is hard to define and measure
Who developed the Cognitive interview?
Geiselman et al (1984). Aims to increase accuracy of EWT through use of cues
Pickel (1998)
Pps watch a thief enter hair salon carrying scissors (high threat, low surprise), hand gun (high threat, low surprise), wallet (low threat, low surprise), or a whole raw chicken (low threat, high surprise). Identification least accurate in high surprise conditions.
What are the four principles of the cognitive interview?
1) Context reinstatement or mental reinstatement of original context (mentally recreate physical and psychological environment of original incident)
2) Report everything (even irrelevant information)
3) Recall in changed order (since recollections are influenced by schemas and prevents pre-existing schemas influencing recall)
4) recall from changed perspective (disrupts schemas)
Enhanced cognitive interview (ECI)
Fisher (1987) added elements to the CI that focus more on social dynamics
What are Enhanced cognitive interviews?
Interviewer must know when to establish eye contact and when to relinquish it
Also included ideas such as reducing eyewitness anxiety, minimising distractions, getting the witness to speak slowly and asking open ended questions
Increases effectiveness of eyewitness recall
What are the strengths of the Cognitive interview?
- Supporting research, Gieselman et al (1986)
Gieselman et al (1986) method
Staged intruder with blue rucksack enters and steals slide projector and 2 days later they are questioned with standard interview and CI with misleading question
What were the results and conclusion of the Gieselman et al (1986) study?
CI participants less likely to recall the rucksack colour wrong and shows a reduction in effect of leading questions in CI
What are the weaknesses of CI
- Time consuming - Requires training - May not apply to every day life (staged vs real life crimes) - Less successful with children
