Introduction to Eyewitness Testimony
Eyewitness testimony (EWT) is a legal term. It refers to an account given by people of an event they have witnessed. For example they may be required to give a description at a trail of a robbery or a road accident someone has seen. This includes identification of perpetrators, details of the crime scene etc.
Eyewitness testimony is an important areas of research in cognitive psychology and memory.
Jurys tend to pay close attention to EWT and generally find it a reliable source of informtion. However, research into this area has found that EWT can be affectd by many psycholgical factors:
- Reconstructive Memory
- Weapon Focus
- Leading Questions
Reconstructive Memory
In other words, we tend to see and in particular interpret and recall what we see according to what we expect and assume is ‘normal’ in a given situation.
Bartlett
referred to these complete mental pictures of how things are expected to be as schemas. These schemas may, in part, be determined by social values and therefore prejudice.
Schemas are therefore capable of distorting unfamiliar or unconsciously ‘unacceptable’ information in order to ‘fit in’ with our existing knowledge or schemas. This can, therefore, result in unreliable eyewitness testimony.
In his famous study 'War of the Ghosts', Bartlett (1932) showed that memory is not just a factual recording of what has occurred, but that we make “effort after meaning”. By this, Bartlett meant that we try to fir what we remember with what we really know and understand about the world. As a result, we quite often change our memories so they become more sensible to us.
His participants heard a story and had to tell the story to another person and so on, like a game of “Chinese Whispers”. The story was a North American folk tale called “The War of the Ghosts”. When asked to recount the detail of the story, each person seemed to recall it in their own individual way. With repeating telling, the passages became shorter, puzzling ideas were rationalised or omitted altogether and details changed to become more familiar or conventional. For example, the information about the ghosts was omitted as it was difficult to explain, whilst participants frequently recalled the idea of “not going because he hadn’t told his parents where he was going” because that situation was more familiar to them. For this research Bartlett concluded that memory is not exact and is distorted by existing schema, or what we already know about the world.
This clearly indicates that our memories are anything but reliable, ‘photographic’ records of events – they are individual recollections which have been shaped & constructed according to our stereotypes, beliefs, expectations etc.
The implications of this can be seen even more clearly in a study by Allport & Postman (1947).
When asked to recall details of this picture, participants tended to report that it was the black man who was holding the razor.
Clearly this is not correct and shows that many is an active process and can be changed to 'fit in' with what we expect to happen based on your knowledge and understanding of society (e.g. our schemas).
Weapon Focus
This refers to an eyewitness’s concentration on a weapon to the exclusion of other details of a crime. In a crime where a weapon is involved, it is not unusual for a witness to be able to describe the weapon in much more detail than the person holding it.
Loftus et al. (1987) showed participants a series of slides of a customer in a restaurant. In one version the customer was holding a gun, in the other the same customer held a chequebook. Participants who saw the gun version tended to focus on the gun. As a result they were less likely to identify the customer in an identity parade those who had seen the chequebook version
However, a study by Yuille and Cutshall (1986) contradicts the importance of stress on weapon and focus in influencing eyewitness memory.
They showed that witness of a real life incident (a gun shooting outside a gun shop in Canada) had remarkable accurate memories of a stressful event involving weapons. A thief stole guns and money, but was shot six times and died. The police interviewed witnesses, and thirteen of them were re-interviewed five months later. Recall was found to be accurate, even after a long time, and the two misleading questions inserted by the research team had no effect.
The Yuille and Cutshall study illustrates three important points:
1. There are cases of real-life recall where memory for an emotional / stressful event is accurate, even some months later.
2. Misleading questions need not have the same effect as has been found in laboratory studies (e.g. Loftus & Palmer)
3. Contrary to some research, “weapon focus” does not always affect recall.
Leading Questions
Loftus has been particularly concerned with how subsequent information can affect an eyewitness’s account of an event. Her main focus has been on the influence of (mis)leading information in terms of both visual imagery and wording of questions.
Loftus’ findings seem to indicate that memory for an event that has been witnessed is highly flexible. If someone is exposed to new information during the interval between witnessing the event and recalling it, this new information may have marked effects on what they recall. The original memory can be modified, changed or supplemented.
Key Study: Loftus and Palmer (1974)
Aim: To test their hypothesis that the language used in eyewitness testimony (EWT) can alter memory. Thus, they aimed to show that leading questions could distort EWT accounts and so have a confabulating effect, as the account would become distorted by cues provided in the question. To test this they asked people to estimate the speed of motor vehicles using different forms of questions. Estimating vehicle speed is something people are generally poor at and so they may be more open to suggestion.
Procedure: Forty-five American students formed an opportunity sample. This was a laboratory experiment with five conditions, only one of which was experienced by each participant (an independent measures design).
Participants were shown slides of a car accident involving a number of cars and asked to describe what had happened as if they were eyewitnesses. They were then asked specific questions, including the question “About how fast were the cars going when they (hit/smashed/collided/bumped/contacted ) each other?”
Thus, the IV was the wording of the question and the DV was the speed reported by the participants. A week after the participants saw the slides they were asked “Did you see any broken glass?” There was no broken glass shown in the slides.
Results: The estimated speed was affected by the verb used. The verb implied information about the speed, which systematically affected the participants’ memory of the accident. Those who were asked the “smashed” question thought the cars were going faster than those who were asked the “hit” question. The participants in the “smashed” condition reported the highest speeds, followed by “collided”, “bumped”, “hit”, and “contacted” in descending order.
When people were asked a week after viewing the film whether they saw any broken glass at the scene (there was none), people in the smashed group were more likely to say yes. Therefore, a leading question that encouraged them to remember the vehicles going faster also encouraged them to remember that they saw non-existent broken glass. The question appears to have modified the memory itself.
Conclusions: This research suggests that memory is easily distorted by questioning technique and information acquired after the event can merge with original memory causing inaccurate recall or reconstructive memory. The addition of false details to a memory of an event is referred to as conflabulation. This has important implications for the questions used in police interviews of eyewitnesses.
Criticisms: The research lacks mundane realism, as the video clip does not have the same emotional impact as witnessing a real-life accident and so the research lacks ecological validity.
