Eye Witness Testimony

How do leading questions effect EWT

When dealing with eyewitness testimony (EWT) it is vital not to use leading questions as this could affect the memory of the eyewitness and the accuracy of their testimony

What might leading questions result in

Response bias

When did Loftus and Palmer research into the effects of leading questions on EWT?

1974

What was the aim of L+P 1974 study

To investigate the ways in which memory can be influenced

What was the experimental design of L+P 1974 study

• Independent groups

• Questionnaire

• Opportunity sample (Washington university)

Outline the procedure of L+P 1974 study

• 45 students shown films of traffic accidents

• Ps divided into 5 groups

• There was one critical question about how fast the cars were going, each group had a different verb

What was the IV of the L+P study

Verb used in the critical question

What was the DV in the 1974 L+P study

What was the DV in the 1974 L+P study

What were the 5 verbs used in the critical questions

• Hit

• Smashed

• Collided

• Contacted

• Bumped

Define misleading information

Incorrect information given to an eyewitness usually after the event

• It can take forms such as: leading questions and post event discussion between co-witnesses an other people

Outline the findings of L+P 1974 study on leading questions on EWT

• Mean estimated speed calculated for each group

• Verb contacted = speed of 31.8 mph

• Verb smashed = 40.5 mph

• The leading questions biased the EWs recall of the event - the more violent the verb, the higher estimated speed

Why do leading questions affect EWT

(in terms of the difference between response and substitution bias)

Response bias

• Suggest that the wording of the question has no real effect on the p's memories but influences how they decide to answer

Substitution bias

• L+P 1974 - second experiment

• Proposes that the wording of a leading question changes the p's memory of the film clip

• This was shown because ps who heard the word smashed were more likely to report seeing broken glass (there wasn't any) the critical verb altered their memory of the incident

When did Gabbert et al research post event discussion (PED)

2003

What was the aim of Gabbert et al's 2003 study on PED

To investigate wether or not a discussion or event after it had occurred could alter someone's memory

Define post event discussion (PED)

This involves eyewitnesses discussing the events and their experiences after it has occurred

Outline Gabbert's procedure into PED

ED - Lab study & independent groups

• Ps watched a video of a girl stealing money but from different angles, giving some a clearer view than others

• Ps discussed the video before answering the questions

• There was a control group where there were no discussions

What were the results of Gabbert's 2003 experiment

71% of witnesses recalled information they hadn't seen

• In the control group it was 0%

Why does PED affect EWT (in terms of memory contamination and memory conformity)

Memory contamination

• When co-witnesses discuss the event together, their memories can become distorted

• This is because they combine misinformation from other witnesses into their own memories

Memory conformity

• Gabbert et al concluded that witnesses often go along with each other - either for social approval or because they believe the other witnesses are right and they're wrong

• Unlike MC, the memory is unchanged

Evaluate the strengths of research into LQ and PED

Real world application

• Important practical uses in the justice system, as the consequences of inaccurate EWT can be very serious

• Loftus 1975 - argues police have to be very careful on their phrasing of questions, psychologists are often asked to act as expert witnesses in order to explain the limits of EWTs to juries

• Shows that psychologists can improve the way the legal system works, by protecting innocent people from faulty convictions based on unreliable EWTs

Gabbert's study was a lab based

• Lab studies are easy to replicate; this means there is high reliability to the findings of the investigation

• Ability to control EVs and CVs = increased internal validity

Evaluate the limitations of research into LQs & PED

L+P was a lab study

• Eyewitnesses to car accidents are likely to experience high levels of stress which does not happen with lab-based research

• Participants in lab studies may not take the experiment seriously or give the same motivation if they were witnessing a real-life situation

• Answers given by participants may be prone to demand characteristics

Evidence against substitution

• EWT is more accurate for some aspects of a situation than others

• Sutherland and Hayne 2001 - showed ps a video clip, when asked misleading q's, their recall was more accurate for central details of the event rather than peripheral ones

• Presumable the ps were focussed on the central features of the event, and these memories were relatively resistant to misleading information

• These memories not being distorted aren't what the substitution explanation would predict

Evidence against memory conformity

• Evidence that PED actually alters EWT

• Skagerberg and Wright 2008 showed p's film clips

• There were 2 versions - muggers hair was light or dark brown - Ps discussed in pairs, each seeing a different clip - they either didn't report what they had seen or a blend of what they had seen

• Suggests that memory itself is distorted through contamination by misleading PED, rather than the result of memory conformity

Define anxiety

Anxiety is an emotion that brings on feelings of tension, worry and physical changes such as raised blood pressure

Define the Weapon Focus Effect (WFE)

• negative effect on recall

WFE tends to happen during the commission of a crime in which a weapon is used

• The eyewitness may fixate on the weapon due to fear or the fight-or-flight response

• Due to this intense focus on the weapon, the person wielding it is not really noticed

• Thus, recall of the details of the perpetrator is virtually non-existent

Who researched the WFE

Johnson & Scott (1976)

Outline Johnson and Scott's 1976 study on WFE

• Participants were told they were taking part in a lab study and were asked to sit down in a waiting area

• Participants were split into a low-anxiety group or a high-anxiety group (the two conditions of the independent variable)

• Participants were asked to identify the man from a set of photographs

Low anxiety group

• The low-anxiety group overheard a casual conversation from a room and saw a man walk out with a pen and grease on his hands

High anxiety group

• The high-anxiety group overheard an argument from the room and saw a man walk out with a knife and blood on his hands

What were the findings of Johnson and Scott's 1976 study on WFE

• The low-anxiety group correctly identified the man with a mean accuracy of 49%

• Accuracy dropped to 33% in the high-anxiety group

• The researchers concluded that anxiety focuses attention on the weapon and away from other details of the event

Why might anxiety have a positive effect on recall

• Anxiety may have a positive effect on the recall of events during a stressful situation

• This positive effect may be due to an increase in the hormone adrenaline which triggers the 'fight, flight or freeze' response which results in a state of high alertness

Who conducted research on the positive effect of anxiety on recall

Yuille & Cutshall (1986)

Outline Yuille & Cutshall's 1986 procedure

• Witnesses of a real-life crime shooting (in Vancouver Canada) were asked to take part in the study

  • 13/21 took part

• Participants were interviewed four to five months following the shooting; the interviews were compared to police interviews

• Accuracy was measured by the number of matching details in each interview

• Participants were also asked to rate their stress levels at the time of the incident (using a seven-point scale) and related issues

What were the findings of Yuille & Cutshall's 1986 study

• The witness's recall was accurate as events recalled four to five months later matched original police reports

• Witnesses who reported high-stress at the time of the incident had the most accurate recall with 88% accuracy

• Low-stress witnesses had less accurate recall with 75% accuracy

• The findings stress that anxiety does not have a negative effect on the recall of events or the accuracy of EWT, in fact it may enhance the accuracy of recall

Explain why the findings by Johnson and Scott (1976) contradict the findings of Yuille & Cutshall (1986)

• Yerkes & Dodson (1908) proposed that there is a relationship between arousal (emotion state) and performance

• When a crime is witnessed, a person becomes emotionally (anxiety) and physiologically(adrenaline release) aroused

• Low levels of arousal (anxiety) are associated with low levels of performance (recall and accuracy of EWT)

• As arousal increases performance increases up to an optimum

• After this point, as arousal continues, performance begins to decrease

Evaluate the strengths of search into the effects of anxiety on EWT

Support for negative effects

• Studies support the idea that anxiety leads to less accurate recall:

• Valentine & Mesout (2009) found that participants' recall of actors in the London Dungeons was less accurate with high-anxiety compared to low-anxiety

• This study used an objective measure of heart rate to measure anxiety and so has high validity

Support for positive effects

• Studies support the idea that anxiety leads to higher accuracy of EWT:

• Christianson & Hubinette (1993) found higher recall in witnesses to a real-life bank robbery

• Victims of the robbery (high anxiety) had better recall of the details of the robbery compared to bystanders (low anxiety)

• This suggests that anxiety improves the accuracy of EWT and supports the study of Yuille & Cutshall

Evaluate the limitations of research into the effect of anxiety on EWT

J+S may not have tested anxiety

• It is argued that Johnson and Scott did not test anxiety but instead fear or surprise

• Other research has found that EWT is less accurate when unusual objects are involved (Pickel 1998)

  • experiment used scissors, a handgun, a wallet and raw chicken as the hand held items in a salon video (scissors would be high anxiety, low unusualness)

  • EW was significantly poorer in the high unusualness conditions (chicken and handgun)

• This suggests that the weapon focus effect is due to surprise rather than anxiety, and that their research is limited in the WFE explanation

Problems with the 'law of arousal'

• The Yerkes-Dodson Law does not take into account all the factors that contribute to anxiety, such as cognition, emotional state and physical health which would all affect the accuracy of EWT

• This suggests that the Yerkes-Dodson Law may be too simple

Define the Cognitive Interview (CI)

A method of interviewing EWs to help them retrieve more accurate memories

What are the 4 components of the CI

• Report everything

• Reinstate the context

• Reverse the order

• Change perspective

Who devised the CI

Fisher and Geiselman (1984)

Outline the purpose of 'Reporting everything' in the CI

During the second stage, the eyewitness is asked to report all details of the event without any editing of seemingly irrelevant details

• One specific memory may connect to another and may act as a cue for other important memories

Outline the purpose of 'Reinstating the context in the CI'

The purpose of this stage of the interview is to make the memories more accessible by giving contextual and emotional cues

• This is related to context-dependent forgetting

Outline the purpose of 'reversing the order' in the CI

The purpose of this is that schemas influence the perspective and recollections of events

• Recalling events in reverse order prevents preconceived ideas from influencing what can be recalled as well as dishonesty (it's harder to lie if they have to reverse the account)

What's the purpose of 'Changing the perspective' in the CI

The purpose of this stage is to disrupt the effect of the schemas and prevent a schema overlayingthe memory

• Witnesses should try to recall the event from other people's perspectives

Outline the enhanced cognitive interview (ECI)

• Fisher et al 1987

• Added additional elements to focus on the social dynamics of the situation, for example, the interview needs to know when to establish eye contact and when to relinquish it

• The ECI also aims to

  • minimise distractions, getting the EW to speak slowly, minimise EW anxiety and ask open-ended questions

Evaluate the strengths of the CI

Support for the effectiveness of the CI

• Supporting research on the effectiveness of CI is a meta-analysis carried out by Kohnken et al. (1999) who analysed 55 different studies comparing CI and standard police interviews

• The findings showed that CI improved the accuracy of EWT by 41%

• This suggests that the CI is an effective procedure to aid witnesses in recalling accurate memories that are available but not immediately accessible following an event

Evaluate the limitations of the CI

Some elements may be more useful

• not all elements are effective or useful

• Milne and Bull 2002

  • found that each of the 4 techniques alone produced more information than a standard police interview

  • also found that a combination of report everything and reinstate the context produced better recall than any other combination of them - confirming police suspicions that some aspects are more useful than others

• Casts dome doubt on the overall credibility of the CI

Time consuming

• Carrying out a CI is a time-consuming process

• Police officer's time is limited and there may be resistance to carrying out a full CI due to the time constraints involved in not only conducting the interview but also training police officers in the technique (Kebbell and Wagstaff 1997)

• This suggests that carrying out a full CI is not a realistic procedure for police officers to use