2.4 Eyewitness Testimony

Eyewitness testimony

The ability of people to remember the details of events, such as accident and crimes, which they themselves have observed. Accuracy of EWT can be factors such as misleading information and anxiety.

Misleading Information

Incorrect information given to an eyewitness usually after the event. It can take many forms, such as leading questions and post-event discussion between co-witnesses and other people.

Leading question

A question which, because of the way it is phrased, suggests a certain answer. For example: ‘Was the knife in his left hand?’ leads a person to think that’s where the knife was.

Post event discussion

Occurs when there is more than one witness to an event. Witnesses may discuss what they have seen with co-witnesses or with other people. This may influence the accuracy of each witnesses recall on the event.

Leading questions: Loftus and Palmer: Procedure

Loftus and Palmer arranged for 45 participants to watch film clips of car accidents and then asked them questions about the accident. In the critical question participants were asked to describe how fast the car were travelling ‘about how fast were the cars travelling when they hit each other?"‘

There were 5 groups of participants and each group was given a different verb in the critical question. One group had the word hit, the others had the words, contacted, bumped, collided, smashed.

Leading questions: Loftus and Palmer: Findings

The mean estimated speed was calculated for each participant group. The verb contacted resulted in a mean estimated speed of 31.8 mph. For the verb smashed, the mean was 40.5. The leading question biased the eyewitness’s recall of an event.

Why do leading questions affect EWT?

The response-bias explanation suggests that the wording of the question has no real effect on the participants’ memories, but just influences how they decide to answer.

Loftus and Palmer conducted a second experiment that supported the substitution explanation. Participants who originally heard smashed were later more likely to report seeing broken glass those who had heard hit. This critical verb altered their memory of the incident.

Research on post event discussion: Procedure

Gabbert et al. studied participants in pairs. Each participant watched a video of the same crime, but filmed from different points of view. This meant that each participant could see elements in the event that the other could not.

Research on post event discussion: Findings

The researchers found that 71% of the participants mistakenly recalled aspects of the event that they did not see in the video but had picked up in the discussion. The corresponding figure in a control group, where there was no discussion, was 0%. This was evidence of memory conformity.

Why does post event discussion effect EWT?

Memory contamination. When co-witnesses to a crime discuss it with each other, their eyewitness testimonies may become altered or distorted. This is because they combine information from other witnesses with their own memories.

Memory conformity. Gabbert et al. concluded that witnesses often go along with each other, wither to win social approval or because they believe the other witnesses are right an they are wrong. The memory is unchanged.

Misleading Information Evaluation: Strengths

-It has important practical uses in the criminal justice system. The consequences of inaccurate EWT can be very serious. Loftus believes that leading questions can have such a distorting effect on memory that police officers need to be very careful about how their phrase their questions when interviewing eyewitnesses.

-The research performed by Gabbert et al. was a lab study and therefore it is easy to replicate and there is high reliability to findings.

Misleading Information Evaluation: Limitations

-One limitation of the substitution explanation is that EWT is more accurate for some aspects of an event that others. Witnesses’ memories are more accurate for central details of an event rather than peripheral ones. Therefore those memories are relatively resistant to misleading information.

-Another limitation of the memory conformity explanation is evidence that post-event discussion actually alters EWT. In an experiment participants were show two versi9ons of a Clio, one where a mugger had dark hair and the other, light hair. Participants discussed the clips in pairs, each having seen different versions. Often, the report from the witnesses was mix of the two, ‘in between dark and light hair’. Suggesting that the memory is distorted throughly contamination of mis-leading information, rather than the result of conformity.

Anxiety has a negative effect in recall

Anxiety creates psychological arousal in the body which prevents us from paying attention to important cues, so recall is worse.

Weapon focus: Procure

Johnson and Scott did an experiment on this and participants believed they were taking part in a lab study. While seated in a waiting room participants in the low-anxiety condition heard a casual conversation in the next room and then saw a man walk past them carrying a pen and grease on his hands. Other participants overheard a heated argument, accompanied by the sound of breaking glass. A man walked out of the room, holding a knife covered in blood. The was the high anxiety condition.

Weapon focus: Findings

The participants later picked out the man from a set of 50 photos, 49% who had seen the man carrying the pen were able to identify him. The corresponding figure for the participants whop had seen the man holding the knife was 33%. The tunnel theory of memory argues that people have enhanced memory for central events. Weapon focus as a result of anxiety can have an effect on this.

Anxiety has a positive effect on recall: Procedure

The fight or flight response is triggered, increasing alertness. This may improve memory for the event as we become more aware of cues in the situation.

Yuille and Cutshall conducted a study of an actual shooting in a gun shop in Vancouver, Canada. The shop owner shot a thief dead. There were 21 witnesses- 13 took parti in the study. They were interviewed 4 to 5 months after the incident and they were compared to the original police interviews. Accuracy was determined by the number of details reported in each account. The witnesses were also asked to rate how stressed they had felt at the time and whether they had any emotional problems since the event.

Anxiety has a positive effect on recall: Findings

The witnesses were very accurate in their accounts and there was little change in the amount recalled or accuracy after 5 months-though some details were less accurate, such as recollection of the colour of items and age/height/weight estimates. Those participants were recorded the highest levels of stress were most accurate. This suggests that anxiety does not have a detrimental effect on the accuracy of eyewitness memory in a real-world context and may even enhance it.

Explaining the contradictory finings- Yerkes-Dodson law

According to Yerkes and Dodson, the relationship between emotional arousal and performance looks like an ‘inverted U’.

Lower levels of anxiety/arousal produce lower levels of recall accuracy, and then the memory becomes more accurate as the level of anxiety/arousal increases. However, there is an optimal level of anxiety, which is the pointy of maximum accuracy. If a person experiences any more arousal, then their recall suffers drastic decline.

Evaluation of anxiety: Strengths

-There is evidence supporting the view that anxiety has a negative effect on the accuracy of recall. The study by Valentine and Meson supports the research on weapon focus, finding negative effects on recall. The researchers divided the participants into high and low anxiety groups. Anxiety clearly disrupted the participants’ ability to recall details about the actor in the London Dungeon’s Labyrinth. This suggests that a high level of anxiety does have a negative e effect on the immediate eyewitness recall of a stressful event.

-There is evidence supporting that anxiety can have a positive effects on the accuracy of recall. Christianson and Hubinette interviewed 58 witnesses to actual bank robberies in Sweden. Some of the witnesses were directly involved and some were indirectly involved. The researchers assumed that those directly involved would experience the most anxiety. It was found that recall was more than 75% accurate across all witnesses. The direct witnesses were even more accurate.

Evaluation of anxiety: Limitations

-Johnson and Scott’s study argues that anxiety may not have tested anxiety. The reason participants focused on the weapon may be because they were surprised at what they saw rather than scared (unusualness) . Pickel conducted an experiment using scissors, a handgun and a wallet or a raw chicken as the hand-held items in a hairdressing salon video. ( scissors would be high anxiety, low unusualness). Eyewitness accuracy was significantly poorer in the high unusualness conditions.

-Christianson and Hubinette interviewed their participants several months after the events and therefore they had a lack of control over confounding variables. Invalidating their support.

Cognitive interview

A method of interviewing eyewitnesses to help them retrieve more accurate memories. It uses four main techniques, all based on evidence-based physiological knowledge of human memory- report everything, reinstate the context, reverse the order and change perspective.

Report everything

-Encouraged to include every single detail of the event , it may be important or trigger other memories.

Reinstate the context

-Return to the original crime scene in their mind and imagine the environment and their emotions.

Reverse the order

Events should be recalled in a different order from the original sequence. This is done to prevent people reporting their expectations of how the event must have happened rather than reporting the actual events. It also prevents dishonesty. ( harder for people to produce an untruthful account if they have to reviser it. )

Change perspective

Witnesses should recall the incident from other people’s perspective. This is done to disrupt the effect of expectations and also the effect of schema on recall. The schema you have for a particular setting generate expectations of what api;d have happened and it is the schema that is recalled rather than what actually happened.

The enhanced cognitive interview

Fisher et al. developed some additional elements of the CI to focus on the social dynamics of the interaction, For example, the interviewer needs to know when to establish eye contact and when to relinquish it. The enhanced CI also includes ideas such as reducing eyewitness anxiety, minimising distractions, getting the witness to speak slowly and asking open-ended questions.

Evaluation of cognitive interview: Strengths

-There is evidence that the cognitive interview works. a meta-analysis combined data from 55 studies comparing CI with the standard police interview. The CI gave an average 41% increase in accurate information compared with the standard interview.

Evaluation of cognitive interview: Limitations

-Not all elements of the CI are equally effective/useful. Milne and Bull found that each of the four techniques alone produced more information than the standard police interview. But they also found using a combination of report everything and reinstate the context produced better recall than any of the other elements or combination of them.

-CI is time-consuming and requires more training than standard police interview.