eyewitness testimony

Factors affecting eye witness testimony

1. Misleading information

2. Anxiety

Two researchers who studied the role of misleading information on EWT

1. Loftus and Palmer

2. Gabbert

Procedure of Loftus and palmer study into misleading information

45 students shown films of car accidents and were asked to estimate how fast the cars were going when they ‘hit’ each other, some participants had this question whilst others had the verb smashed, contacted, bumped or collided

Results of Loftus and Palmer study

Average speed estimate with the word contacted was used was 31.8mph whilst with smashed it was 40.5mph- almost a 10mph difference between the harshest sounding verb and gentlest sounding verb

Procedure for Gabbert post event discussion study

60 students and 60 members of the local community and were put into pairs. Each participant separately wat he’d a video of the same crime (Mooney stone from wallet) but filmed from different angles. This means the participants could see elements in the event the other could not. Both participants discussed what they had seen with each other having to be led to believe they watched the same video and then participants completed test of recall NOT MATCHED PAIRS

Results of Gabbert post event discussion study

71% of participants mistakenly ‘recalled’ aspects of the event that they did not see in the film but had picked up through the discussion

60% said the girl was guilty despite not seeing her take the money

Explanation of why leading questions affect EWT

RESPONSE BIAS- wording of the question has no real effect on memory but does influence how the question is answered (a bit like demand characteristics)

SUBSTITUTION- the wording of the question actually changes memory

What did Loftus and Palmer find in further research

Participants who had the leading questions 17% reported they had seen glass

Memory conformity

Either to win social approval or because they believe the other is right

Evaluate research into effect of misleading information on EWT

• Real life application- Loftus and Palmer found that misleading questions can affect memory recall, useful to police as to ensure validity of EWT they know not to use leading questions and police can contextualise Gabbert study by not allowing witnesses to have a post event discussion which could alter their memories

• Low in ecological validity- used artificial stimuli meaning it lacks a real life aspect of memory and participants will be aware there is no consequences to what they say e.g. if they agree the girl stole money when in fact they did not see her do so

Weapon focus effect

When a weapon is present the anxiety this induces causes the witness to focus so much on that weapon that they do not recall more peripheral details e.g. what the perpetrator looked like

Yorkers-Dodson law

A bit o anxiety at the time can actually improve recall but too much anxiety impairs later recall

Johnson and Scott study on anxiety impairing EWT (results and procedure)

Procedure- participants believed they were waiting to take part in some research were exposed to either: low anxiety (overhead a casual conservation in the next room and then witnessed a man leave the room carrying a greasy pen) or a high anxiety group (overheard a heated argument and the sound of breaking glass in the next room and then witnessed a man leaving the room holding a bloody knife) participants were then asked to identify the man from a set of 50 photos

Results- 49% of people in low anxiety group and 33% of people in high anxiety group were able to correctly identify the man

Yuille and Cutshall study on anxiety affecting EWT (procedure and results)

Procedure- 13/21 witnesses in a real life shooting outside a Gun shop in Vancouver Canada agreed to take part in the study and were interviewed 4-5months after incident and their responses were compared to their police interviews straight after the event and the participants were also asked to rate how anxious they felt at the time of the event on a 7-point scale and whether they had experienced any subsequent problems

Results- participants who reported highest stress levels were the most accurate- about 88% accurate whereas those who were less stressed about 75% accurate

Evaluate Johnson and Scott study on anxiety affecting EWT

• High In internal validity- controlled e.g. same man each time therefore can establish change in % of correctly identifying man must be due to anxiety

• Ethics- informed consent not received, participants are being deceived and psychological harm (more stress than everyday) so breeches guidelines

• High in ecological validity- participants believe it is a real life situation so less prone to demand characteristics, participants act authentically, therefore we can generalise results to others

• Alternative explanations- Pickell found poor recall in the presence of both a gun and a raw chicken in comparison to scissors or a wallet in a video set in a hairdressers This suggests that unusualness rather than anxiety may be what causes poor recall

Evaluate Yuille and Cutshall study on anxiety affecting EWT

• Not Generalisable- small sample size, bias volunteer sample, can’t use for less severe crimes therefore cannot generalise results to larger target population

• Application to real life- proven reliable so can be used in court and police don’t have to worry about leading questions

• Low in internal validity- accuracy was judged by comparing to original interview regather than what actually happened therefore may not actually be measuring EWT accuracy

• High in ecological validity- real life situation so they will behave authentically and there will be no demand characteristics

• Ethics- psychological harm, making participants discuss a traumatic event can cause stress, justifiable: minimises harm and maximises benefit

Improving the accuracy on EWT

The cognitive interview

Cognitive interview

Method of interviewing to help EW retrieve more accurate memories

Four main techniques of cognitive interview

1. Report everything

2. Reinstate context

3. Reverse the order

4. Change perspective

Enhanced cognitive interview techniques

• Take steps to ensure anxiety is reduced

• Maintain eye contact at certain times but not others

• Take steps to minimise interruptions

• Speak slowly

• Ask opened ended questions

Evaluate cognitive interview

• Time consuming and expensive- link to psychology and the economy

• Supporting evidence- Konken found cognitive interview gave a 41% increase in accurate information compared to standard police interview. Suggests CI are very effective. Furthermore, thus study was a meta-analysis of 55 studies and only four of these studies showed no difference between the types of interviews so fairly strong and convincing evidence. However, they also found the enhanced cognitive interview lead to more inaccurate recall, which suggests that these additional techniques are not beneficial, ad police should stick to using the four main techniques of the cognitive interview.

• Supporting evidence- Milne and Bull found each technique used on its own produced more information than a standard police interview but that report everything and reinstate context used together produced the most recall of any other combinations. This suggests that if the police are on a tight time scale or low on resources they should focus on these two techniques alone.