Eye witness testimony

• Eyewitness testimony - Information recalled about a crime by an eyewitness.
• Factors affecting eye witness testimony

  • Accuracy may decrease through the influence of misleading information in the form of leading questions and post-event discussions.
• Leading questions:

  • Investigated by Loftus and Palmer (1974)

  Participants watched a clip of a car crash and then gave speed estimates of the cars based on leading questions. Each group was exposed to a different verb (eg - smashed, contacted etc). Those exposed to the verb 'smashed' gave an estimate of 8.7mph greater than those who heard 'contacted'. This suggests leading questions, because of the way they are phrased, suggest there is a correct answer.
• Post-event discussion - Discussions which take place between co witnesses after the crime has taken place.

  This is subject to the influence of media and TV reports on the crime, as well as participant's pre-conceived expectations of how they would imagine the crime.
• Post-event discussion

  Gabbert et al (2003) - Used a matched pairs design and showed participants a film clip of a crime scene, but with different details for each member. After a test of recall, the researchers found 71% inaccuracy rates of information gained through such discussions, compared to 0% control group who had worked alone throughout.
• Post-event discussions also demonstrate the idea of 'memory conformity', where we are more likely to pick up on incorrect details or ideas because we believe we are wrong and the other person is right.

  
  

  Bonder (2009) set up a study similar to Gabbert. Participants were discouraged from sharing information in their testimony. Findings showed there was significantly less information gained from other witnesses, suggesting if warned about the dangers of post-event discussion, effects can be reduced.
• Limitations of EWT:

  • Age bias - Anastasia and Rhodes argued studies on EWT often use the same, young target to identify. This may be affected by own age bias, - the tendency to recall others from your own age group with a high degree of accuracy, with lower accuracy for those of other age groups. This means participants aged 55-78 years may be inaccurately represented as having a lower accuracy of EWT, due to the frequent use of young targets.
• Limitations of EWT:

  • Demand characteristics - Reduces reliability of findings. Zaragosa and McCloskey suggested participants often want to be as helpful and attentive as possible. This means that through the mechanism of social desirability, or when in doubt of their own answer, they're less likely to give a beneficial answer, thus biasing the results and reducing validity if the study was conducted again.
• Limitations of EWT:

  • Lacks mundane realism - Artificial tasks (Loftus and Palmer, alongside Gabbert) reduces ecological validity of the realism and methodology. For example, the film clips of the car crashes do not expose participants to the anxiety of experiencing a real life car crash. This anxiety may have a negative (Johnson and Scott) or positive (Yuille and Cutshall) effect on the accuracy of EWT (bias of the findings).
• Factors affecting the accuracy of EWT

  • Anxiety - A physiological response to external pressures, characterised by an increase in heart rate, sweat production, vasoconstriction of blood vessels etc. Anxiety can either have a positive or negative effect on EWT.
• Anxiety on EWT:

  • Johnson and Scott (1976) - Anxiety has a negative effect on the accuracy of EWT. High-anxiety condition overheard a heated argument in the next room with the sound of glass shattering and a man walking through the waiting room with a bloody paper-knife, as opposed to a greasy pen in the low-anxiety condition. When asked to identify the man, participants in the HA condition experienced 16% lower accuracy rates than the LA condition. This may be explained by the tunnel theory of memory and weapon focus effect, where the weapon is the source of anxiety.
• Anxiety on EWT:

  • Yuille and Cutshall (1986) - Anxiety has a positive effect on EWT. Followed up 13 eyewitnesses, 5 months after a real-life shooting at a shop in Canada. Recall accuracy was still high; 11% higher of those who ranked their anxiety as 'high' at the time of the shooting, (7 point anxiety scale). This supports the idea that heightened anxiety draws our attention to external cues through the 'fight or flight' response, where such attention may have increased our chances of survival. It suggests misleading information and anxiety may not be a problem for the real world of EWT.
• Limitations of anxiety on EWT:

  • Yerkes-Dodson Law - There is an inverted U relationship between increased anxiety and increased performance, with moderate anxiety yielding the highest levels of performance. BUT this can be considered as an overly-simplified explanation of anxiety because it does not take into account the multiple factors which make up arousal (eg- cognitive, behavioural, emotional etc).
• Limitations of anxiety on EWT:

  • Loss of objectivity - Weapon focus may be testing for effects of surprise rather than anxiety. Pickel found that the highest levels of accuracy of EWT were experienced in the condition with high unusualness (eg - a raw chicken in a hairdressing salon). This suggests the weapon focus effect can only be used to explain certain influences of anxiety on the accuracy of EWT.
• Limitation of anxiety on EWT:

  • Ethical issues - Participants exposed to distressing images of a car crash (Johnson and Scott) and forcing them to recall traumatic crimes that have occurred in the past (Yuille and Cutshall). This breaches the BPS guidelines of the right of the participant to be protected from psychological harm, meaning that a cost-benefit analysis should be conducted.
• Limitations of anxiety on EWT:

  • Extraneous variables - Yuille and Cutshall's field study could not have controlled the influence of post-event discussions, which have been suggested to reduce the accuracy of EWT, as demonstrated by Gabbert et al. Alongside media, TV reports and effects of individual schemas mean that field studies of EWT may be flawed (lack reliability).
• Cognitive interview - A method of interviewing eyewitnesses, thought to be effective in increasing rates of accurate recall.
• Steps of cognitive interviews:

  • Report everything - Even seemingly insignificant details may be important or trigger the recall of larger events by acting as a 'cue'.

  Example - “Please tell me what happened on that day. Start at the beginning; leave nothing out; I am interested in absolutely everything.”
• Steps of cognitive interviews:

  • Reinstate the context - Recalling the weather, location and mood of the day prevents context-dependent forgetting by reminding eyewitnesses of their external cues at the time.

  Example - “I would like you to think back to the day. Try to get a clear picture in your mind. Think of the objects that were there, the colours, smells, sounds. What were you feeling?”
• Steps of cognitive interviews:

  • Change the perspective - Recall events from the perspective of another (victim / criminal) prevents the eyewitnesses' account from being affected by their own schemas or pre-conceived perceptions of how the crime happened.

  Example - “Try to recall the incident from the perspective of another person involved. Describe what he/she would have seen.”
• Steps of cognitive interviews:

  • Reverse the order - Recall events in another order, other than chronological, reduces the ability of the eyewitness to lie (as it is difficult) and reduces the impact of schemas on the perception of the events.

  Example - “I would like you to tell me what happened backwards. I know it sounds hard, but start with the very last thing you remember?”
• Cognitive interviews were introduced by Fisher et al (1987) and focus on the social dynamics of the interactions between eyewitness and the interviewer (eg - knowing when to make eye contact, making the eyewitness comfortable and calm).
• Strengths of the cognitive interview:

  • Not all steps must be used - Milne and Bull (2002) found context reinstatement and report everything produced the greatest accuracy of correct information, compared to any other combination of steps. This means that even if police forces don't have enough time to train the entire 4 steps, gradual change from the standard interview can increase the accuracy and reliability of recall and eyewitness testimony.
• Limitations of the cognitive interview:

  • Time consuming / costly - Kebbel and Wagstaff argued only a few hours of training is insufficient to adequately train interviewers, especially for enhanced social understanding required for CI. It requires specialist trainers and a lot of practice. Therefore, a lack of this training may explain why some forces may be unimpressed with CI.
• Limitations of the cognitive interviews:

  • Limited application - Kohnken (1999) conducted a meta analysis of 42 studies including over 2500 interviews. There was a significant increase of 61% more incorrect information recalled. This resulted in similar accuracy rates of the standard interview (82%) and cognitive (85%). This appears counterintuitive when considering the aim of CI was to improve the accuracy of correct information to increase the reliability of EWT as a whole, suggesting it may be of limited practical value due to increased errors.