Eyewitness testimony: Misleading information

• what are the two explanations of misleading questions?

  the response-bias explanation and the substitution explanation
• response-bias explanation of leading questions

  wording of a question has no enduring effect on an eyewitness' memory of an event, but influences the kind of answer given.
• substitution explanation of leading questions

  wording of a question does affect eyewitness memory: it interferes with its original memory, distorting its accuracy.
• procedure of Loftus and palmer: leading questions

  45 participants (students) watched film clips of car accidents and then answered questions about speed. critical questionL 'about how fast were the cars going when they hit each other?'

  five groups of participants, each given a different verb in the critical question: hit, contacted, bumped, collided or smashed.
• what were the five different verbs in Loftus and palmer's study?

  hit, contacted, bumped, collided and smashed.
• findings & conclusions of Loftus and palmer: leading questions

  • the verb 'contacted' produced a mean estimated speed of 31.8 mph
  • for the verb 'smashed' the mean was 40.5 mph
  • the leading question (verb) biased eyewitness recall of an event.
  • the verb 'smashed' suggested a faster speed of the car than 'contacted'
• what two things are involved in post-event discussion (PED)?

  memory contamination and memory conformity.
• memory contamination

  when co-witnesses discuss a crime, they mix (mis)information from other witnesses with their own memories.
• memory conformity

  witnesses go along with each other to win social approval or because they believe the other witnesses are right.
• procedure of gabbert et al: post-event discussion

  • paired participants who watched a video of the same crime, but filmed so each participant could see elements in the event that the other couldn't
  • both participants discussed what they had seen on the video before individually completing a test of recall
• findings & conclusions of gabbert et al: post-event discussion

  • 71% of participants mistakenly recalled aspects of the event that they didn't see in the video but had picked up in the post-event discussion
  • in a control group, where there was no discussion, there were no errors.
• strength of misleading information: real-life applications

  the research had led to important practical uses for police officers and investigators, important because the consequences of inaccurate EWT can be very serious. loftus claimed leading questions can have such a distorting influence on memory that police officers need to be careful about how they phrase questions when interviewing eyewitnesses. research into EWT is one area where psychologists can make an important difference to the lives of real people, e.g. by improving how the legal system works and acting as expert witnesses
• limitation of Loftus and palmer's study: artificial materials

  participants watched film clips of accidents, a very difference experience from witnessing a real accident (e.g. it is less stressful). yuille and cutshall found that witnesses of a traumatic real armed robbery had very accurate recall after four months. this shows that using artificial tasks tells us little about how leading questions affect EWT in real crimes or accidents.
• limitations of misleading information: may be individual differences in accuracy

  anastasi and rhodes found that older people were less accurate than younger people when giving eyewitness reports. however, they also found that all age groups were more accurate when identifying people of their own age group (own-age bias). research studies often use younger people as the target to identify. so some age groups may seem less accurate but this is not really the case.
• who studied post-event discussion?

  gabbert et al.
• who studied leading questions?

  Loftus and palmer
• limitation: many EWT research studies lack external validity

  foster et al. argue that what you remember as an eyewitness can have important consequences in the real world, but the same is not true in research studies. real eyewitnesses search their memory with more effort because their testimony may lead to a successful conviction (or wrongful if inaccurate). this is not true in research studies. therefore EWT accuracy may be greater in the real world because of the seriousness with which eyewitnesses undertake their role