Eyewitness Testimony

Factors affecting EWT

• leading question

• post-event discussion

• anxiety

What is Eyewitness Testimony

• details of crime

• provided by a witness of it

What is a Leading Question

• wording may mislead to give certain answer

• may direct witness towards a particular answer

Research into Leading Questions

loftus and palmer speed of car

loftus and palmer glass at accident

Overview of Research into Car Accident

• 45 participants in 5 groups

• watched same film clips of car accident

• after they’re given questions about accident

• describe how fast cars travelling

• different verbs are used

• e.g. contacted vs smashed

Results of Research into Car Accident

• more aggressive verb = faster estimate mean speed

• smashed = 40.8 mean second average

• contacted = 31.8 mean second average

Overview of Research into Glass Experiment

• 150 students in 3 groups

• shown clip of car accident

• asked how fast cars were travelling

• one asked hit, smashed, how fast (control)

• 1 week later asked if glass present after crash

• no glass was

Results of Research into Glass Experiment

higher number saw glass with smashed than other conditions

Conclusion of Research into Glass Experiment

leading questions alter memory of event

Research Support strength of Leading Questions

• Loftus asking question with low or high number demonstrators

• asked to estimate number of demonstrators

• gave lower or higher number based off question

• negatively influence memory affecting answers

• BUT demand characteristics of helpfulness internal validity

Real-World strength of Leading Questions

• research used to warn criminal justice system of EWT

• important role and value of EWT research

• innocent people not convicted of not committed crimes

• CJS careful not ask leading questions so don’t rely

Mundane Realism criticism of Leading Questions

• different watching clip to witnessing in real life

• artificial task less influence on EWT than research suggests

• not reflective of real life

• external validity cannot apply outside experiment setting

Other Factors criticism of Leading Questions

• witness accurate memory of high stress real life event

• resistant to effects of misleading questions

• leading question little effect on recall accuracy

• stress has more influence - anxiety

What is Post-Event Discussion

• eyewitnesses discuss after the event

• experience and memories

• with others involved or who give input

Research into Post-Event Discussion

gabbert et al crime POV

Overview of Research into Post-Event Discussion

• paired participants shown different video

• same crime filmed

• each saw elements of crime other didnt

• all pairs allowed to discuss

• then individually did recall test

Results of Research into Post-Event Discussion

• 71% recalled aspects not in their video

• 0% recalled aspects not in their video in control with no discussion

2 Reasons for these Results

• memory contamination

• memory conformity

Memory Contamination

• actually distorted memories

• due to discussion

• combined misinformation from other witness

• with own memories

Memory Conformity

• memories aren’t distorted

• go along with witness

• to gain social approval

• or believe they are right and individual isn’t

Research Support strength of Post-Event Discussion

• discuss crime video 1 week after

• memory heavily influenced by information shared in discussion

• PED distort memory since incorporated details and decrease accuracy

• important factor to minimise to prevent inaccuracy

Social Media strength of Post-Event Discussion

• exposed to misleading PED performed worse on later recall test

• tiktok style video delivering information was worst

• misleading detail can directly distort memory with format more vulnerable

• PED real threat and credible explanation for inaccurate PED

Contradict criticism of Post-Event Discussion

• witness collaborate produced fewer errors than lone recall

• PED not universally negative factor

• not always lead to memory contamination as witnesses can correct others mistakes

• PED not always distort memory, nuance research needed about EWT

Incomplete criticism of Post-Event Discussion

• effects depend on additional factors e.g. source credibility

• research found more influenced by misleading information from highly credible source (police) than low-cred source (child)

• PED alone can’t explain memory accuracy issues

• social factors play major role, incomplete explanation cannot be relied solely on

What is Anxiety

• unpleasant emotional state

• stress induced

• result in physiological arousal

• e.g. increase heart rate, blood pressure, breathing, sweatiness

What is this Law

Yerkes-Dodson Law

What does Yerkes-Dodson Law suggest about Anxiety

performance is best under moderate anxiety

Weapon Focus Effect

• anxiety of seeing weapon

• focuses all attention onto weapon

• won’t be able to recall much else

Research into Anxiety

johnson and scott - negative effects

yuille and cutshall - positive effects

Overview of Research into Negative Effect of Anxiety

• wait in reception alone

• low anxiety = overheard argument next room then left room with grease covered hand and pen

• high anxiety = overheard argument and glass break next room then left room running with paper knife covered in blood

• both groups shown 50 pictures identify person

Results of Research into Negative Effects of Anxiety

• low anxiety = 49% successful identification

• high anxiety = 33% successful identification

Conclusion of Research into Negative Effects of Anxiety

• weapon focus effect

• high anxiety reduces accuracy of EWT

Overview of Research into Positive Effects of Anxiety

• interview real witnesses of real crime

• gun shooting incident

• 13/21 witnesses took part in study

• various locations of witnesses

• interviewed again 4-5 months later

• compare recording to original interview

• accuracy = number of details reported

• asked to rate how stressed at time of incident 7-point scale

• asked emotional state before incident

• asked problems caused by incident e.g. sleepiness

Results of Research into Positive Effects of Anxiety

• witnesses very accurate

• little change in amount of accuracy after 5 months

• some details less accurate

• e.g. colour, age, height, weight estimates

• high level stress witnesses most accurate

• high stress = 88%

• low stress = 75%

Research Support of Negative Effects of Anxiety

• london dungeon high anxiety (heart monitor) recalled fewer details about encountered actors

• 17% high could identify line up 75% low could

• anxiety negatively impact if too high

• CJS consider in EWT identifying criminals

Research Support strength of Positive Effects of Anxiety

• witnesses to bank robbery had good memory for details

• most anxious had best recall

• enhances recall not inhibits by becoming aware

• real life scenario strong support increase validity

• BUT real-life lack control of extraneous variables of discussion or prior memory

Contradictory criticism of Weapon Focus Effect

• thief enter hair salon carrying scissors, handgun or raw chicken

• eyewitness accuracy poorer on raw chicken

• accuracy poorer - unusual sight not anxiety

• WFE due to surprise not threat - no tell on effects of anxiety

Theory criticism of Yerkes-Dodson

• ignores many elements of anxiety (cognitive, behavioural, emotional, physical)

• focus on physical arousal as only element linked with EWT

• simplistic approach to impact of anxiety as cognitive may majorly effect

• limited, incomplete explanation future research should focus on all components to fully understand

How to Improve the Accuracy of EWT

cognitive interview

What were features of Standard Interview

• sequential approach (chronological order)

• structured approach (prepared questions)

• specific questioning (closed, leading)

• less emphasis on psychological principles (optimising memory recall)

What is the Cognitive Interview

• police technique for interviewing witnesses

• encourages retrieval more accurate memories

• 4 techniques

What are features of Cognitive Interview

• report everything

• reinstate the context

• reverse the order

• change the perspective

Report Everything

• report every detail

• including trivial or irrelevant information

• unimportant detail might act as trigger for key information

Reinstate the Context

• mentally reinstate environment and personal context of crime

• asking general activities and feelings on day

• asked to use all 5 senses in recollection

• helps recreate event clearly

Reverse the Order

• recount incident in different narrative order

• from end to beginning

• prevent people reporting expectation (schema)

• and not actual event

• prevent dishonesty as harder to produce untruthful account if reversed

Change the Perspective

• report incident from a different perspective

• other witness or criminal might have seen

• aids recall reduces witness’ prior knowledge, expectation or schema

Elevated Cognitive Interview

• social dynamics

• e.g. maintain/establish eye contact

• e.g. ask open ended question

• e.g. get witness to speak slowly

Research Support strength of Cognitive Interview

• watch film of violent crime and 48 hours later interviewed by police with cognitive, standard and hypnosis interview

• cognitive highest number of correctly recalled facts

• effective in improving memory for events

• BUT artificial task lacks mundane realism

Real-Life strength of Cognitive Interview

• trained miami police department detectives to use CI

• produced 46% increase recall and 90% accuracy

• provides clear, real life evidence CI is more effective than standard

• important implication and CI use all the time to improve accuracy

Time Consuming criticism of Cognitive Interview

• requires specialist training and interview takes longer

• unlikely proper version of interview is used

• difficult to accurately evaluate effectiveness

• some elements more valuable so police should focus on using those elements if time is limited

Not Effective criticism of Cognitive Interview

• 41% increase correct information but also increase inaccurate information

• even though effective it increases inaccuracy

• questions if should be used or not

• police should treat eyewitness evidence from cognitive interview with caution too