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EyewitnessTestimony

Page history last edited by PBworks 13 years ago


Critical Issue: Eyewitness Testimony

 

Introduction

An important explanation of organisation in human memory relies on the concept of schemas. These are simplified, generalised representations of things based on our experience. If you try to remember what you had for lunch on Christmas Day last year, you will probably find that the memory is as much influenced by the idea of a typical Christmas lunch, as it is by the actual details of the lunch itself. Memory capacity limitations prevent us from remembering precise details about our everyday lives, but schemas allow us to overcome these limitations because we can summarise the regularities in our lives. There is a cost to this, however, in that we may mistakenly ‘recall’ events that never really happened, because they make sense within a particular schema.

 

Reconstructive memory

Much of what we recall from LTM is not an accurate representation of what was presented to us. We organise incoming material and impose meaning upon it so that what we recall is effectively our version of what happened, which may be more or less accurate. The fact that memory works in an active way like was first demonstrated in experiments by Bartlett (1932) by using the technique known as serial (or repeated) reproduction.

 

He gave participants complex and unusual stories such as a North American Indian folk story called ‘The War of the Ghosts’ (see activity below) and asked them to reproduce it six or seven times over various retention intervals. Although there was some accurately recalled information, the stories were distorted and altered in various ways.

 

Many studies have supported Bartlett’s speculations (e.g. Hunter 1964), and have extended his findings to related phenomenon. Spiro et al (1980) demonstrated that even a simple story will be remembered in different ways, according to the particular viewpoints of the participants. (They used a story about an engaged couple where the man was against having children.)

 

The criticism that is sometimes made about Bartlett method is that the reason the story is poorly reproduced is that it is written in an unusual style. To try to improve the ecological validity of Bartlett’s study, Wynn & Logie (1998) asked students about an event that had happened to them earlier in the year. As most people would probably predict, their results contradicted Bartlett. They found that memories were actually very resistant to change over the year. However, this study is not a direct replication of Bartlett’s, since the information was an episode that had happened to the individual. This type of information is likely be so well-remembered that it will be less subject to the kind of distortions that more unfamiliar material will be prone to.

 

Activity: Replicating the War of the Ghosts Study

 

Eye-witness testimony

Bartlett’s ideas have been developed and extended by Elizabeth Loftus in relation eyewitness testimony (EWT). Loftus believed that the reconstruction of memories was one of the reasons why EWT was often inaccurate. For example, witnesses might try to fit information into a schema resulting in distortions. Another aspect of memory that she emphasises is interference by post-event information (such as that which might be introduced during questioning).

 

Reliability of eye-witness accounts

Eye-witness testimony is often a vital factor taken into account by juries in deciding whether defendants are guilty or not guilty. It is important, therefore, that we have some idea of how reliable these testimonies really are. The answer to this question seems to be that they are not always very accurate. Cromberg et al. (1996) interviewed people one year after an air crash in Amsterdam. Of the 193 questioned, 55% said that they had seen the plane hit the building when they had not and 59% inaccurately reported that a fire had started immediately on impact.

 

This should not surprise us. Bartlett (1932) suggested that although we think we remember accurately, we are continually trying to make sense of what is around us and our memories tend to be fitted into existing schemas. This process is known as effort after meaning. Loftus’s research shows that memory is not simply a ‘tape-recording’ of past events.

 

Effects of leading questions

According to Loftus, one way of adding information after the event is by the questions asked by interviewers. A leading question is one that is phrased in such a way that it suggests a particular answer to the witness. Loftus & Palmer (1974) showed how leading questions might affect the way that memory is recalled.

 

In a further investigations, Loftus and her colleagues showed how quite subtle changes of wording during questioning may distort recall (Loftus & Palmer, 1974 and Loftus & Zani, 1975).

Criticisms of this type of research, however, suggest that it lacks ecological validity as it is laboratory based and does not have the emotional impact of witnessing an incident. Also, research has focused on the recall of ‘peripheral’ details and, as Fruzetti et al. (1992) point out, it is more difficult to distort witnesses’ memory for key details such as the murder weapon involved in the incident.

 

Role of emotional arousal

Experimental evidence shows us that emotional arousal can lead to poor recall for details. Loftus et al (1978) showed a film of a hold-up and then tested memory for details. The results showed that a high-arousal version of a young boy being shot and falling to the floor clutching his bleeding face, led to poorer recall than a low-arousal version. However, research into so-called ‘flash-bulb memories’ does show that in certain circumstances memory can be intensified by emotionally charged events.

As a result of evidence from eye-witness studies, in 1976 the Devlin Report recommended that judges should instruct juries that it is not safe to convict on a single eye-witness alone, except in exceptional circumstances such as the witness is a friend or relative, or when there is substantial corroborative evidence.

 

Cultural variations in recall

It seems that the race or culture of the person attempting to recall information, and that of the person about whom the information is to be recalled, can have an impact upon the accuracy of recall.

Goldstein & Chance (1985) suggest that recognising faces is a complex skill that we develop and improve upon. However, to do this we have to have experience of the faces we want to recognise. Western people tend to experience difficulties in recognising faces of Japanese people. Similarly, to many Asian or black people, whites all look very similar. But these effects tend to come from lack of experience in meeting people from the different groups. With experience, we can soon learn to be more sensitive to the differences in people’s faces.

 

Improving recall

Hogg & Vaughan (1996) have examined a number of factors that lead to improved accuracy of eye-witness testimony. For example, it can help if the witness goes back over the scene or the crime to reinstate additional cues. It also helps if the witness was exposed to the person’s face for a long time and give their testimony a very soon after the crime. Certain personality factors are also important, i.e. does the witness habitually attend to his/her surroundings and does he/she generally form vivid mental images. Finally it helps if the person’s face was not altered by disguise and if he actually looks dishonest!

 

More controversial is the idea that hypnosis will aid eye-witness memory. Many studies have found no advantage from using this technique (e.g. Smith, 1983). Indeed, Orne et al. (1984) have shown that hypnosis can actually distort recall.

 

Some of the reasons why evidence gathered under hypnosis should be treated with caution are as follows:

  • People may pick up on suggestions communicated by the hypnotist and incorporate these into their own memory — in effect ‘leading questions’ are more likely to produce distorted memories.
  • Hypnotised people sometimes ‘see’ things that were not there and fail to report things that were there.
  • Confidence with which people give information is high even though it may be incorrect. This may lead to false trails in the investigation.
  • If hypnosis makes mental images more vivid, hypnotised people may confuse these images with actual memories.

 

[Based on findings by Laurence & Perry (1983), Rathus (1987) and Hassett & White (1989).]

 

The conclusion of a panel appointed by the American Medical Association was that hypnosis sometimes produces additional details that are unreliable. Police are recommended to limit its use to the investigative stage of an enquiry where it may produce clues whose details could be checked by other sources rather than accepting recall under hypnosis as evidence itself.

Other methods of improving recall have been more widely accepted. One such technique, the cognitive interview, has proved to be a better tool at extracting information than the standard police interview with no more errors (Fisher & Geiselman, 1988). The technique uses four strategies designed to maximise recall:

 

  • Mentally reinstating the environmental and personal context that existed at the time of the crime.
  • Reporting everything regardless of its perceived importance
  • Recounting events in a variety of different orders
  • Reporting the events from a variety of perspectives

 

References: EWT

 

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