eye witness testimony

what is a Leading questions

 questions that make it likely that a participant’s schema will influence them to give a desired answer. E.g. how fast was the car driving when it bumped/smashed….?

what is Misleading information

incorrect information given to the eyewitness that may alter a memory after the event. Information that suggests a desired response.  E.g. What colour was the man’s tie?

what is Post-event discussion

a misleading conversation after an incident has occurred that may alter a witnesses’ memory. Information added to a memory after the event has occurred.  E.g. discussing what you have seen with other witnesses or other people.

Loftus & Palmer experiment procedure

• Experiment 1: 45 student participants were put into groups and shown short films involving car accidents. After each film they were shown, they were given a questionnaire to fill in, where only one question was critical: estimation of the speed that the cars were travelling at. 

• There were five different conditions for this experiment, which differed only by the phrasing of the critical question. In one group, participants were asked “how fast do you think the cars were travelling when they hit each other”, and another was asked “how fast do you think the cars were travelling when they smashed into each other”. The only word that differed between the groups was the choice of verb. Apart from ‘hit’ and ‘smashed’, the words ‘collided’, ‘bumped’ and ‘contacted’ were used also. 

• Altogether, there were seven films shown to the participants. In order to get a precise series of results, the average estimation was taken for each participant group. 

Findings of Loftus and Palmer

Findings Loftus and Palmer found significant differences between the average estimations depending upon the severity of the verb: 

• ‘smashed’ gave an average estimate of 40.8mph 

• ‘collided’ gave an average estimate of 39.3mph 

• ‘bumped’ gave an average estimate of 38.1mph 

• ‘hit’ gave an average estimate of 34.0mph 

• ‘contacted’ gave an average estimate of 31.8mph 

The more extreme the verb was in the question, the higher the average estimation of the cars’ travelling speeds. 

This allowed Loftus and Palmer to conclude that leading questions did have an effect on eyewitnesses accuracy of recall.

factors affecting accuracy of ewt in loftus study

Loftus and Palmer (1975) Misleading Information Experiment

Experiment 2: New participants watched a video of a car accident and were asked similar ‘speed’ questions to Experiment 1.  A week later some participants were also asked “Did you see any broken glass?”.  There was no broken glass in the video,  but more participants in the ‘smashed’ condition reported seeing some. 

Conclusions: Loftus and Palmer concluded that the phrasing of the questions had a clear effect on witnesses’ answers, and therefore that leading questions and misleading information can affect the way that eyewitnesses respond.