factors affecting accuracy of eyewitness testimony

• effects of misleading information

  leading questions - questions that suggest a certain answer - e.g. Did you see the knife?

  post event discussion - where two witnesses have a conversation after a crime has taken place - could make a witness think something else had happened
• leading questions research aim and method

  Loftus and Palmer

  AIM - investigate effects of misleading information on accuracy of eyewitness testimony

  METHOD - lab - 45 students (5 groups of 9) shown 7 fits of different car accidents - after each film participants given questionnaire asking to describe accident and answer questions - one critical question: 'How fast were the cars going when they hit each other?' - other 4 groups replaced hit with smashed, collided, bumped or contacted - calculated mean speed estimates for each condition
• leading questions research findings and conclusion

  FINDINGS - mean speed estimates: smashed (40.8 mph) collided (39.3 mph) bumped (38.1 mph) hit (34 mph) contacted (31.8 mph)

  conclusion - leading questions can affect accuracy of eyewitness testimony and may cause information to be changed before its stored so the memory is permanently affected
• LEADING QUESTIONS EVALUATION - high degree of control over variables

  study conducted in controlled environment of laboratory and potential extraneous variables could be easily controlled - e.g. Loftus and palmer ensure lighting and noise levels same when viewing film for each participant - high internal validity
• LEADING QUESTIONS EVALUATION - practical applications

  may be used to warn the criminal justice system about problems with eyewitness evidence - e.g. juries warned against fully trusting evidence from eyewitnesses - may help to avoid inaccurate judgements being made in court
• LEADING QUESTIONS EVALUATION - sample unrepresentative

  participants only one type of person not generally representative of population - e.g. students may be above average intelligence
• LEADING QUESTIONS EVALUATION - Yuille and Cutshall


  4 months after real life robbery in Canada, 13 eyewitnesses not affected by leading questions and gave same responses they'd given in initial report straight after robbery - concluded misleading information doesn't effect real life EWT due to level of anxiety and emotion experienced in real life - doesn't generalise to real life EWT
• post event discussion research aim and method

  Gabbert et al

  AIM - test effects of post event discussion on accuracy of eye witness testimony

  METHOD - 120 participants in pairs - shown video of girl returning borrowed book to university office from different points of view - one partner could read the title and one could see the girl commit a crime of sliding £10 note out of a wallet into her own pocket - participants discussed what they had seen before individually completing recall test
• post event discussion research findings and conclusion

  FINDINGS - 71% of participants mistakenly recalled aspects of event they didn't see - control group with no discussion was 0% - 60% of participants who couldn't see the crime reported the girl as guilty despite not witnessing it take place

  CONCLUSION - witnesses go along with each other due to memory conformity - either to win social approval or because they believe the other witnesses are right and they are wrong
• POST EVENT DISCUSSION EVALUATION - easy to replicate

  study was conducted in controlled environment (laboratory) and used video of crime, easy to use over and over again - e.g. same video can be shown in same conditions - can easily be tested for reliability
• POST EVENT DISCUSSION EVALUATION - practical applications

  can warn eyewitnesses about second hand information from other witnesses to reduce these problems - e.g. before giving evidence warned about memory conformity and how it can unfairly influence criminal justice system - avoid inaccurate judgements in court
• POST EVENT DISCUSSION EVALUATION - positive effect on economy

  developing strategies to combat effects of post event discussion should help improve efficiency in legal system - e.g. allowing police to spend less time and money investigating inaccurate claims - reduces waste in the system
• POST EVENT DISCUSSION EVALUATION - mock crimes lack consequences of real life crimes

  participants aware the information they give doesn't have a serious consequence as it would for eyewitnesses in real life where the information they give can lead to people being wrongly sent to prison - e.g. less likely to say they saw the girl commit crime if they hadn't in real life as it could have a damaging effect on her life - lacks ecological validity