Factors affecting eyewitness testimony

Factors affecting eyewitness testimony

• Memory research can have valuable applications in everyday life

Misleading information

• Research tells us that one of the main factors affecting the accuracy of memory for an event seems to be what happens after the event has taken place
• Memories are fragile and subject to distortion by post-event information

Leading question

• Procedure
  • Loftus and Palmer arranged for ppts to watch film clips of car accidents and then gave them a questionnaire about the accident
  • In the critical question (a leading question) ppts were asked to describe how fast the cars were travelling: 'About how fast were the cars going when they ____ each other?'
  • Hit
  • Contacted
  • Collided
  • Bumped
  • Smashed
• Findings
  • The mean estimated speed was calculated for each group
  • The verb 'contacted'=31.8mph
  • Smashed=40.5mph
  • The leading question biased the eyewitness recall of the event
• Why do leading questions affect EWT?
  • The response bias explanation suggest that the wording of the question has no real effect on the ppts memory but instead influences how they choose to respond to the question

Post-event discussion

• When co-witnesses to a crime discuss it with each other, their eyewitness testimonies may become contaminated
• This is because the combine (mis)information from other witnesses with their own memories
• Procedure
  • Gabbert studied ppts in pairs
  • Each ppt watched a video of the same crime but from a different point of view
  • This meant that each ppt could see elements in the event that the other could not
  • Bothh ppts then discussed what they had seen before individually completing a test of recall
• Findings
  • The researchers found that 71% of the ppts mistakenly recalled aspects of the event that they did not see in the video but had picked up in the discussion
  • The corresponding figure in the control group with no discussion was 0%
  • Gabbert concluded that witnesses often go along with each other, to win social approval or because they believe others are right and they are wrong
  • Memory conformity

Evaluation of misleading information

+Research into misleading information has real-life applications

• This research has led to important practical uses for the police, important because consequences of inaccurate EWT can be very serious
• Loftus claimed that 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
• Practical applications, improving the legal system 

-Loftus and Palmer's study used artificial materials

• Ppts watched a film clip of accidents, a very different experience from witnessing a real accident
• Yuille and Cutshall found that witnesses of a traumatic real armed robbery had very accurate recall after four months
• Shows that using artificial materials tells us little about how leading questions affect EWT in real crimes/accidents

-Lab studies of EWT suffer from demand characteristics

• Research ppts usually want to be helpful and attentive
• So when they are asked a question and do not know the answer, they guess
• Ppts might give answers they believe to be more helpful
• This challenges the validity of EWT research
• …