Conducted a classic experiment to investigate the effect of leading questions on the accuracy of eyewitness testimony
Sample
45 American students, divided into five groups of nine
Experiment procedure
1. Participants watched a video of a car crash
2. Asked a specific question about the speed of the cars
3. Loftus and Palmer manipulated the verb used in the question
Verb used in the question
Affected the estimated speed
Verbs used
smashed
collided
bumped
hit
contacted
Participants who were given the verb "smashed" reported an average speed of 40.5 mph, while those given "contacted" reported 31.8 mph, a difference of 8.7 mph
The results show that the accuracy of eyewitness testimony is affected by leading questions and a single word in a question can significantly affect the accuracy of judgements
Second experiment
150 American students, divided into three groups
Watched a one-minute video of a car accident
Given a questionnaire to complete
Questionnaire
1. One group asked "How fast were the cars going when they smashed into each other?"
2. Another group asked "How fast were the cards going when they hit each other?"
3. Control group not asked about speed
Verb used in the question
Affected the likelihood of participants reporting seeing broken glass (which was not actually present)
32% of "smashed" group reported seeing broken glass, 14% of "hit" group, and 12% of control group
