An expert witness is an expert in a particular area that may be called as a witness to inform the jury about technical issues or research and interpret the psychological aspects of a crime. They are able to give an opinion whereas a standard witness is only able to give factual evidence, (Ryan, 2010). An expert witness in this case would inform the jury about the reliability of eye witness testimony.
Reliability and validity issues when using expert psychological witnesses.
The use of expert witnesses is often encouraged in cases that rely on eye witnesses where there is no other evidence. This allows the jury to understand the limitations of eye witness accuracy to ensure an individual is not falsely convicted. Cutler, Dexter and Penrod (1989) supported the need for expert testimony as it improves juror's knowledge of the reliability of an eye witness's evidence. Expert witnesses give general information on the reliability and accuracy of eye witnesses as they re not directly involved in the specific case they cannot give evidence of a specific witness's testimony, (Preussel, 2006). This may be problematic as the evidence given is not directly related to the case which could confuse jurors and influence the results of the case.
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Benton, Ross, Bradshaw, Thomas and Bradshaw (2006) looked at jurors' knowledge of eyewitness accuracy compared to that of expert witnesses. It was found the average person has little understanding on the influencing factors within the accuracy of eye witness memory; which suggests expert witnesses would be useful in some cases relying on evidence in this area. However, a lack of knowledge with the jury may cause them to over rely on the expert information which may influence the results of a case retrospectively. Research by Preussel (2006) showed that the defence can raise issues of identification accuracy within eye witness testimony without the need of expert witnesses. This can be argued to be more effective as it doesn't completely overlie evidence given by the prosecution.
The information given within court by expert witnesses is often based on research which lacks ecological validity. Participants are normally students therefore the sample findings cannot be generalised across the entire population. Other problems with research used includes that it relies on witnesses of eyewitness memory yet in real life crimes it is generally the victim who gives the most evidence, (Prussel, 2006). This means that the findings and therefore expert information is not as reliable and valid as might be put across within a court case. Preussel (2006) showed there are issues with how memory is tested within eye witness research; studies often rely on how much is recalled rather than the accuracy.
Various researches on eye witness testimony often have conflicting findings. For example some studies have found the theory of weapon focus to be much more of an influence in effecting identification accuracy compared to others. Another example is of the correlation between level of stress and eye witness memory. Yuille and Cutshall (1986, as cited in Kebbell & Wagstaff, 1999) found that participants under more stress made more accurate identifications whereas other research suggests the more stress an individual experiences the less they remember. This therefore shows that expert witnesses within court may actually hinder convictions within a case as the information put forward is not completely reliable and valid.
Information and evidence expert witnesses would put before the court for prosecution.
Expert witnesses are likely to propose that due to the stressful nature of the offence Mrs. Hussain is likely to go over the event in her mind which will help aid an accurate memory of the attacker. Research by Kebbell and Wagstaff (1999) has shown that witnesses find it easier to recognise people rather than accurately describe them. This is supported by the fact both Mrs. Hussain and Mr Hargreaves chose Mr. Kevin Clough as the offender from mug shots and a video identity parade but gave a very limited description of his appearance.
Expert witnesses would consider factors that may affect the accuracy of eye witness statements. In this case it may be argued that the three witnesses were likely to accurately recognise the offender as they have a reason to remember, due to viewing the violent attack. Research by Pezdek and Prull (1993, as cited in Kebbell & Wagstaff, 1999) showed that individuals remember things in more detail if the event is memorable or unusual. Due to the fact both Mrs Hussain and Mr Hargreaves chose Mr Kevin Clough to be the offender in mug shots and a video line up it can be argued that this is reliable evidence to ensure a correct prosecution.
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It is likely in the evidence for prosecution expert witnesses will consider the time lapse between the actual incident occurring and the recognition of the attacker. Mrs. Hussain and Mr Hargreaves both identified the offender two days after the crime took place as this is a fairly short time delay recognition memory should be more complete and accurate. Kebbell and Wagstaff (1999) suggested that in traumatic cases witnesses' memory is more stable and accurate for longer lengths of time as the event is rehearsed.
Expert witnesses will discuss the effects of violence on eye witness memory. Individuals generally experience arousal and stress in situations where violence is used or threatened which may lead to the event being more accurately stored than an everyday non violent situation; this is known as the Yerkes-Dodson law, (Kebbell & Wagstaff, 1999). In this case the victim is being threatened so she is likely to focus her attention on the attacker and what he is doing. Other external influences such as other things or people in the vicinity and other background thoughts are no longer dividing attention as they would in a case where Mrs Hussain was just walking down the street. The stressful situation of being threatened with a knife causes a narrowing of attention focus so Mrs Hussain and the two other witnesses would be concentrating on the attacker which suggests that descriptions and recognition of the attacker is likely to be accurate.
All three witnesses recalled the offender to be male; they also judged him to be within a similar age range which provides support for an accurate eye witness account. Expert witnesses are likely to discuss how eye witnesses are better at estimating the age of those who are of a similar age to themselves, (Kebbell & Wagstaff, 1999). In this case the offender was twenty years of age; the three witnesses were 68, 37 and ten years which are not close at all to the age of the defendant. Due to the fact the three witnesses estimates a similar age for the offender it can be argued that this is an accurate account regardless of the lack of similarity between themselves and the offender in terms of the age gap; this demonstrates how the use of expert psychological witnesses would be effective in terms of prosecution.
Expert witnesses may discuss how witnesses are generally poor at estimating height and build especially when they are of a greater difference to themselves. Both Mr Hargreaves and Freya Odgen estimated the offender to be about six foot; however there was some debate on the build of the offender; medium or slight. Research analysed by Kebell and Wagstaff (1999) shows that witnesses tend to over estimate the build of a violent offender. Expert witnesses of eye witnesses' testimony will put forward research that shows witnesses are more accurate when identifying members of their own race. All three witnesses identified the offender as white; even though they themselves were of different racial backgrounds.
In terms of ensuring a prosecution expert psychological witnesses will be useful for the case when discussing that witnesses descriptions of an offenders clothing tends to be accurate. All three witnesses reported the offender wore dark clothing and a woollen hat. The description given by Freya Odgen was much more detailed due to the offender passing her under a light; she was able to describe colours of the clothing and logo's. This is effective to ensure a conviction of the offender to see if these descriptions match.
Expert witnesses may consider eye witnesses confidence levels when identifying an offender. Sporer, Penrod, Read and Cutler (1995, as cited in Kebbell & Wagstaff, 1999) proposed that a witness who is 'slightly confident' is more likely to accurately identify the offender compared to those witnesses who state they are not very confident. However, witnesses can be very confident they have picked the right person and be mistaken and vice versa. It is generally assumed the more confident a witness is about something the more likely it is to be accurate. This is supported by a study conducted by Kebbell, Wagstaff and Covey (1996, as cited in Kebbell & Wagstaff, 1999); who found that when participants stated they were 'absolutely certain' on something in 97% of cases they were correct. Mrs. Hussain stated categorically that Mr Clough was the man who stole her bag which provides support for the prosecution due to her certainty.
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Information and evidence expert witnesses would put before the court for defence.
Expert psychological witnesses are likely to raise issues concerning memory when for defending evidence. An individual's perception of an event or an individual is influenced by expectation; people perceive what they expect to perceive, (Moses, 2001). Kebbell and Wagstaff (1999) have shown that in cases of selecting the offender from a line up if the individual doesn't find an exact match they is an underlying tendency to pick a similar one. Perception is a decision-making process and emotions can confuse the thought process. In cases of a high level of arousal due to excitement or stress it is likely that the situation will be memorable but accurate recall of details will be flawed. It may be proposed in court that Mrs Hussain would have been too stressed during the attack to accurately recognise the offender and Mr Hargreaves would not have seen the offender in enough detail due to not being directly involved in the attack.
There are problems with eye witnesses in that their accounts of events are often over relied upon and thought to be more accurate than they actually are (Cutler and Penrod, 1995, as cited in Kebbell & Wagstaff, 1999). Memory is a process that goes through three stages of encoding, storing and retrieval. Encoding is the initial representation of perceived information, what actually enters memory depends on what the individual is focusing their attention on; obviously not everything observed can be encoded due to a limited capacity. Because of this memories for events have gaps; individuals automatically fill in these gaps with prior information of attitudes, beliefs and expectations. Research has also shown that memory for details that are inconsistent with individuals' values can be changed to match expectations, (Kebell and Wagstaff, 1999). Due to the likelihood of errors within memory eyewitness statements should not be relied on to heavily without other supporting evidence. All three witnesses only saw the proposed offender for a small amount of time less details are likely to be observed and noticed reducing the reliability of the identification when using recognition from memory.
Expert witnesses are likely to suggest that Mrs Hussain's attention towards the attacker would be limited due to weapon focus therefore reducing the validity of her account of identifying the offender. In cases of weapon focus the witness gives full attention towards the weapon therefore other details are less well remembered. This is supported by the fact Mrs Hussain described the knife in great detail but gave a limited description of the attacker. It may be argued that her identification of the offender is not reliable enough. Research to support this was conducted by Loftus, Loftus and Messo (1987). Participants watched a video where a cashier was with a customer who held either a gun or a chequebook; eye fixations were recorded on the two items. It was found participants had more and longer fixations on the gun. A problem in this case is that the weapon was never recovered therefore Mrs Hussain's description of the knife could not be matched as belonging to the offender which would have provided evidence for prosecution.
Expert witnesses may question the reliability of identification through viewing mug shots. If a picture of the offender is old it may be dismissed by the witness also more mug shots a witness are shown the less accurate the identification is. Lindsay, Nosworthy, Martin and Martynuck (1994, as cited in Kebbell & Wagstaff, 1999) conducted research which supported this and found that looking at faces can interfere and confuse witnesses' memory when making further identifications. The reliability of Mr Hargreaves' and Mrs Hussain's identifications of the offender may be questioned in terms of accuracy due to this problem. Gorenstein and Ellsworth (1980) found there are some accuracy issues when identifying an offender from both mug shots and a line up. People tend to match the person they identified in the mug shot to the person in the line up rather than looking directly for the offender. Therefore, if the wrong person is selected from photos it is likely the wrong person will be identified within a line up. These findings may be considered when questioning accuracy due to how the offender was identified in this case.
Expert witnesses are likely to put forward evidence which shows that the larger the distance between the witness and the crime the worse the ability is for that individual to accurately remember the crime, (Kebbell and Wagstaff, 1999). Being as Freya Ogden and Mr Hargreaves where some distance away descriptions they gave of the offender may not be accurate. There are also issues with the evidence given by Mrs. Hussain as not only was she attacked from behind the offender also knocked off her glasses and she is short sighted. Due to the lack of reliable witness evidence when describing the offender the defence may propose to the court that the wrong person is being accused.
Other issues when arguing for defence include visibility. The attack took place in January at 7.35pm which would be dark outside therefore reducing eye witnesses' ability to accurately recall details. Freya Odgen may have given a better description due to the fact the offender passed her under street lights, however due to her not identifying the offender after the crime a match cannot be confirmed. Yarmey (1986) showed different groups participants a video of an assault set in various lighting conditions. It was found recognition was more accurate in daylight rather than night time. The prosecution is relying on the identifications of Mrs Hussain and Mr Hargreaves who both observed the offender in poor lighting conditions. Expert witnesses are likely to raise research which supports this theory such as that by Wagenaar and van der Schrier (1994, as cited in Kebbell & Wagstaff, 1999) who found that identification is poor even at a three metre distance if there are no surrounding street lights.
In terms of defence expert witnesses may bring up evidence to question the reliability of the witnesses identifications due to their ages. Research by Wells and Loftus (2003) showed that children have a less well developed memory compared to adults. Being as Freya Ogden is only ten years old her description of the offender may be inaccurate and reduce the reliability of the prosecution evidence. Research to support this was demonstrated by List (1989, as cited in Kebbell & Wagstaff, 1999) who found that children's memory was accurate in 73% of cases, whereas for adults it was 84%. There are also issues with the reliability of older witnesses' accuracy in identifications. Research by Coxon and Valentine (1997, as cited in Kebbell & Wagstaff, 1999) shows that perception declines after the age of forty which reduces the amount of available information seen to be able to be stored and retrieved from memory. Due to Mrs Hussain being 68 the defence may argue her identification of the offender is unreliable due to a decline of perceptual abilities; this matter is also reinforced by the fact her glasses were knocked off during the attack further impinging on her observation.
The appropriateness for the use of expert psychological witnesses in this case
In this case it may be proposed that the use of expert witnesses would be more effective for the defence rather than for prosecution. All three witnesses gave similar descriptions of the offender and two both chose the same individual from mug shots and a line up which suggests a fairly accurate identification. Being as research demonstrates that generally jurors have common sense regarding the reliability of eye witness testimony and the fact there are many issues questioning the reliability and validity of expert witnesses within court I would suggest expert witnesses would not be useful in this case.