Factors Affecting Eye-Witness Testimony

• Leading questions- a question that suggests a certain answer because of how it is phrased
• Post-event discussions (PED)- a discussion between multiple witnesses of the same event, where they detail what they saw
• Response-bias explanation for how leading questions affect EWT:

  • The wording of the questions has no effect on the memory of the event, but influences how people decide to answer.
  • E.g. a leading question with an emotive verb (smashed) encourages pps to choose a higher speed estimate.
• Substitution explanation for how leading questions affect EWT:

  • The wording of the leading question changes a persons memory.
  • Loftus & Palmer (1974)- pps who heard 'smashed' were more likely to repeat seeing broken glass than those who heard 'hit', suggesting that the changed verb altered the memory- there was no glass.
• Contradictory evidence against the substitution explanation:

  • Pps watch a video, then were later asked misleading questions- recall was more accurate for central details rather than peripheral details.
  • Suggests central details were resistant to misleading information and weren't distorted- isn't predicted by the substitution explanation.
• How PED affect EWT- Memory contamination:

  • Co-witnesses discussing their accounts might lead to distortion because they combine mis-information from other witnesses with their own memories.
  • Witnesses can recall accurate and inaccurate info, but can't recall where it came from (source confusion).
• How PED affect EWT- Memory conformity:

  • Witnesses often go along with each other, either to win social approval or because they perceive other witnesses as being right- the actual memory of the event hasn't changed.
• Contradictory evidence against memory conformity:

  • Skagerberg & Wright (2008)- pps shown videos of a mugger (2 versions- one with brown hair, one with lighter hair).
  • Pps discussed the video in pairs and were interviewed separately after- found that pps were more likely to report the hair as being a medium brown.
  • Suggests memory is distorted by contamination, rather than conformity.
• Evaluation of misleading information:

  • Application- leading questions and PED likely cause false witness statements, so the cognitive interview is a better tool for memory accuracy- leads to more accurate witness statements and less false convictions.
  • Low external validity- use of artificial materials in studies (watching a video of a mugging means it will be less anxiety-inducing than in real-life), which lowers the mundane realism so it is less generalisable).
• Evaluation of misleading information:

  • Low internal validity- lab study means more extraneous variables due to demand characteristics- cause and effect cant be established- pps behaviour is distorted.
  • Lack of consequences in lab studies lowers reliability of study- Foster et al- pps who believed they were watching a real robbery gave a more accurate ID of the robber, since they believed it would influence a real-life trial (shows more accurate behaviour from pps).
• Anxiety- a state of emotional and physical arousal. Emotions include fear and feelings of tension, physical changes include increased heart rate and sweating
• Negative effect of anxiety on memory recall:

  • Johnson and Scott- anxiety creates physiological arousal in the body, preventing us from paying attention to important info, resulting in worse recall (sensory overload causes us to freeze).
• Weapon-focus effect- when we hyperfocus on the weapon during a crisis situation, leading to us ignoring the other key details, because the weapon causes anxiety
• Positive effect of anxiety on memory recall:

  • Christianson & Hubinette or Huille & Cutshall- physiological arousal within the body triggers the flight response, causing an increased alertness of the environment. This could improve memory (pupils dilate so more light can enter, improving vision).
• Explanation of contradictory findings:

  • Yerkes and Dodson Law- states that performance increases with stress, to a certain point, where it then decreases drastically.
  • Deffenbacher (1983)- reviewed 21 studies of EWT, found supportive evidence of Yerkes and Dodson Law- performance increases as anxiety increases until the optimal level. Any higher anxiety, recall accuracy declines.
• Alternative explanation:

  • Pickel (1998)- argues against Johnson & Scott, says it doesn't test anxiety, it tests surprise (reaction to the weapon).
  • Robber walks into hairdressers, holding one of four options- scissors, handgun, wallet, raw chicken. Pps watch video of robbery.
  • Accuracy of witnesses is worse in high surprise conditions (handgun and chicken), suggests weapon focus is due to surprise, not threat- pps expect the scissors or wallet to be in that environment).
• Evaluation of anxiety affecting EWT:

  • Low external validity- artificial anxiety in lab studies (Johnson & Scott) lacks mundane realism- doesn't represent real-life anxiety, so it's less generalisable.
  • Low internal validity- anxiety is subjective- difficult to operationalise, reliant on self-report and inference (less certainty of cause and effect).
  • Confounding factors influence memory, so anxiety doesn't provide a full explanation.
  • Contradictory evidence suggests the effect of anxiety on EWT is complex (research doesn't focus on cognition, emotion or behaviour, so it is reductionistic).