factors effecting the accuracy of eyewitness testimony

What is the eyewitness testimony?

• an account or evidence provided by people who witnessed an event, such as a crime, reported from their memory

• In appeals against conviction is the US, DNA evidence has overturned over 200 cases and in 75% of these, eye-witness testimony was the main evidence

• E.g. Cornelius Dupree spent 30 years in prison for rape because the victims incorrectly identified him - DNA proved he was innocent

• Variables that could effect EWT - misleading questions, post-event discussion, anxiety felt by those who witnessed or were the victim

Define misleading information

• cognitive psychologists agree that our memories of events are not precise copies of what happened

• We only accurately retain fragments of information and fill in the gaps

• This reconstruction leads to inaccuracies in recall, which can be compounded if we receive information after the event which distorts our original memory

• Any subtle change in the wording of a question can have a dramatic effect on what is recalled

Who researched into misleading information?

Loftus and Palmer

What was Loftus and Palmer’s first experiment?

• two experiments

• P’s viewed films of automobile accidents and then answered questions about events occurring in the films

• Experiment 1 - 45 university students divided into 5 conditions

• The question ‘about how fast were the cars going when they smashed into each other’ - the word ‘smashed’ was changed to collided, bumped, contacted or hit - to see what verb elicited higher speed estimates

What were the results of experiment 1?

• smashed - 40.5mph

• Collided - 39.3mph

• Bumped - 38.1mph

• Hit - 34.0mph

• Contacted - 31.8mph

What was Loftus and Palmer’s second experiment?

• 150 different students split into three conditions

• On condition were asked the question with ‘smashed’, the other condition asked the question with ‘hit’ and the other condition had no question

• On a retest one week later, those p’s who received the ver smashed were more likely to say yes to the question ‘did you see any broken glass?’ - even though there was no broken glass present

What were the results of the second experiment?

• ‘Yes’ - smashed = 16 , hit = 7 , control = 6

• ‘No’ - smashed = 34 , hit = 43 , control = 44

What were Loftus and Palmer’s conclusions?

• in both experiments, it can be seen that the memory of the incident was changed due to the leading question in the first experiment

• These results are consistent with the view that the questions asked subsequent to an event can cause a reconstruction in one’s memory

What are the three evaluation points for EWT?

1 - ❌ validity - Loftus and Palmer

2 - ✅❌ reliability - Loftus

3 - ✅ applications

Evaluation point 1 - validity ❌ (EWT)

P - there is an issue with the validity of Loftus and Palmers research

E - a witness to a real-life car crash is likely to experience a greater emotional response compared with watching one on film, which research has shown may affect the memory of the witnesses in this study

E - other critics suggest that the participants may have worked out the aims of the study, and on hearing the word ‘smashed’, gave the higher answer that they thought the researcher was hoping to get (demand characteristics)

L - if either criticisms are correct, then the findings of these experiment tell us little about real-life eye witness testimony

Evaluation point 2 - reliability ✅❌ (EWT)

P - the reliability of research in this area can be praised as many laboratory studies have found similar findings when p’s are faced with leading questions

E - however, one experiment found that leading questions did not change the accuracy of the EWT when the misleading information was obviously incorrect

E - Loftus showed p’s slides that showed the theft of a large purse from a handbag. 98% of p’s remembered the correct colour of the purse. They were then asked to read an account of the incident that was allegedly written by a professor of psychology. In this account the professor stated that the purse was brown, a false statement as the original colour was red. Only 2 p’s changed their answer to brown on a subsequent test, with most keeping to their original identification of a red purse

L - this means we cannot reliably conclude that all misleading information will have the same effect in all circumstance. The testimony is unlikely to change if the information they relieve and the event they witnessed was obviously different

Evaluation point 3 - applications ✅ (EWT)

P - research into misleading information has led to some important practical applications

E - for example, it has been used to train professionals e.g. the police not to use leading questions when questioning witnesses. In addition, psychologists have also used research in this area to develop the cognitive interview, designed to increase the accuracy of eye-witness testimony

E - as a result, this has lead to positive economic implications. It has helped the conserve limited police resources and money by reducing the likelihood of police officers obtaining inaccurate information about criminal suspects

L - this demonstrates the importance and value of the research conducted into misleading information ans the positive impact it can have on obtaining accurate witness testimonies

Define post-event discussion

• co-witnesses are likely to discuss the event with eye-witnesses and this could be a source of further distortion

• 58% of eye witnesses had reported discussing the incident post-event with other witnesses (Skagerburg and Wright)

• Errors in eyewitnesses accounts can occur when a witness comes into contact with post-event ‘misinformation’

• A common way to encounter misinformation is through face-to-face interaction

• The current research compares this kind of misinformation with the non-social post event narrative method typically in laboratory studies

Who researched into post-event discussion?

Gabbert et al

What did Gabbert et al investigate?

• the effect of post-event discussion on the accuracy of EWT

• Sample of 60 students from the Uni of Aberdeen and 60 older adults recruited from a local community

What was Gabbert et al’s procedure?

• p’s watched a video of a girl stealing money from a wallet

• The p’s were tiger tested individually (control) or in pairs (co-witness group)

• Co-witness group - told that they had watched the same video, however they had seen it from different perspectives and only one person had actually witnessed the girl stealing - they discussed the crime together

• All of the p’s then completed a questionnaire, testing their memory of the event

What were Gabbert et al’s results?

• 71% of the witnesses in the co-witness group recalled information they had not actually seen

• 60% said that the girl was guilty, even though they had not seen her commit a crime

• These results highlight the issue of post-event discussion and the powerful effect this can have on the accuracy of EWT

What are the three evaluation points for post-event discussion?

1 - ❌ validity

2 - ✅ reliability - Gabbert et al

3 - ✅ applications

Evaluation point 1 - validity ❌ (PED)

P - the mundane realism of these research findings are under scrutiny due to the controlled nature of the research

E - an eye-witnesses to a real crime who is then involved in post-event discussion may not act in the same was as the p’s under lab conditions. E.g. there might have been a conformity effect in this research because they knew it was a study. Thus, the outcome of the p’s answers had no social impact and this meant no one would suffer as a result of their testimony

E - this might make them more likely to conform and recall information they hadn’t seen, as there are no consequences for doing so

L - the lack of validity in lab research suggests we must be cautious when making firm conclusions about the role post-event discussion would play in real life testimonies

Evaluation point 2 - reliability ✅ (PED)

P - a strength of the research into post-event discussion in the consistency of the findings

E - there are many search studies that have found similar findings to Gabbert et al. For example, Gabbert et al found that p’s receiving misinformation after an event were less accurate at recalling the event than controls.

E - especially if this information came from a social source compared to a non-social source

L - this means the research into this area has high reliability and allows us to suggest with confidence that EWT can be distorted by post-event discussion

Evaluation point 3 - applications ✅ (PED)

P - research into post-event discussion has many practical applications

E - e.g. police officers should advise witnesses not to discuss the case with any other co-witnesses and will strive to interview the witnesses as soon as possible, to prevent their testimony from being distorted

E - however, in the aftermath of an incident, it would be natural for co-witnesses to discuss what they have just seen. Thus, police officers are advised to take this into consideration when later questioning them on events

L - this demonstrates the value of the research findings and they can be used in many ways to improve the accuracy of testimonies

Define anxiety

• eyewitnesses are often very anxious and stressed when witnessing a crime, especially if they are a victim

• This is because of the danger they perceive to be in

• Anxiety can be a distortion for EWT

• Tends to be accompanied by physiological arousal which affects performance

• The Yerkes-Dobson effect is the observation that arousal has a negative effect on performance when it is very high or very low - can be used to explain errors made by eyewitnesses especially after a violent crime.

Define the weapon focus effect in relation to anxiety

• Loftus argues that anxiety is most problematic for later recall when the crime involves a weapon

• Research suggests that the anxiety of seeing a weapon focuses all of you attention on the central details making you less able to recall the peripheral detailed

Evidence of the weapon focus effect was done by?

Loftus

Loftus et al

What did Loftus’ research say?

• Con 1 - where p’s heard a hostile and aggressive argument by two people in another room, followed by one of them emerging holding a letter opener covered in blood

• Con 2 - heard a harmless conversation between two people, followed by one of them holding a pen with grease on his hands

• P’s were asked to identify the culprit from photographs

What were Loftus’ findings?

• 33% correctly identified the culprit in Con 1

• 49% correctly identified the culprit in Con 2

• Loftus argued that the anxiety caused by seeing the letter opener cased the weapons focus which lead them to not paying attention to other information

What was Loftus et al’s research?

• asked p’s which of two sequences: person pointing a gun at a cashier and receiving cash, and a person passing a cheque to the cashier and receiving some cash

• Found that participants correctly identified details about the incident in the ‘cheque’ condition more than in the ‘gun’ condition

What are the three evaluation points into anxiety?

1 - ❌ internal validity - Johnson and Scott

2 - ❌ reliability and artificiality of research - Yuille and Cutshall

3 - ✅ applications

Evaluation point 1 - internal validity ❌ (anxiety)

P - One criticism of the weapon focus effect is that the effect may not be caused by anxiety.

E - Critics have suggested that Loftus is testing surprise, and not anxiety. In another study, researchers (Johnson and Scott) showed an incident in a hair-dressing salon, but in one condition, the confederate appeared with a raw chicken.

L - This produced just as many inaccurate details as when the incident involved a handgun, suggesting surprise rather than anxiety could account for the weapons effect.

Evaluation point 2 - reliability and artificiality of research ❌ (anxiety)

P - There are differences in the results between research conducted on real-life eye-witnesses and research conducted in a lab environment, showing that there is a lack of consistency in the research.

E - Yuille and Cutshall conducted research into a real-life crime. 13 people, who had witnessed a shop keeper shooting a thief dead in Canada, were interviewed 5 months after the event.

E - These interviews were compared with the original police interviews immediately after the event. Participants were asked to rate how much anxiety they felt during the incident. Those who had reported high anxiety levels reported the highest level of accuracy when recalling the incident five months later (88% accuracy), compared with those who had reported a relatively low level of anxiety (75% accuracy).

L - This is in contrast to Loftus's laboratory findings.

Evaluation point 3 - applications ✅ (anxiety)

P - Research into the effect of anxiety has had important real world applications.

E - Recognising the role of anxiety in EWT has meant the police proceed with extreme caution when pursuing lines of enquiry.

E - Today criminal investigations rarely rely on Eye witness testimony's alone and instead commonly look for alternative evidence, such as DNA sampling or CCTV footage that could be used to collaborate the witness's testimony before charging someone or making a conviction.

L - Therefore research into the effect of anxiety on EWT has had positive benefits for the criminal justice system by reducing the chances of erroneously convicting the wrong person.