Loftus and Palmer
Methodology
Findings
Conclusions
Experiment details
Experiment 1
Participant details
45 students in groups of various sizes
Research method
Experimental design
Independent variable
The verb used in the question: "smashed, hit, contacted"
Dependent variable
The students' responses
Independent measures
Procedures
Experiment 1
Experiment 2
Each participant watched 7 films depicting a traffic accident, each film was from 5-30 seconds and were put in a different order for each group
Part 1
After each film the participant was given a questionnaire
The first thing they had to do was give an account of the accudent
The second part was more specific
The critical question was about the speed of he cars
They were asked "How fast were the cars going when they ___ eachover?"
The blank contained one of the following verbs: "hit, smashed, collided, bumped or contacted"
The participant then estimated the speed of the cars
Controlled lab experiment
Experiment 2
Most details are the same as experiment 1 except:
There were 150 students participating
The independent variable was the questions they were given and what verbs they used to describe the crash
This experiment took place on two dates, the first was about one topic then a week later they asked a something different
The 150 students were put into groups of various sizes
They were shown a 4 second clip of a car accident
After the film the subjects received a questionnaire
They described the accident first and then moved onto more questions
The critical question was about the speed once again
50 were not interrogated about the speed of the vehicles
50 were asked "How fast were they going when they SMASHED into eachover?"
50 were asked "How fast were they going when they HIT eachover?"
Part 2
The subjects returned 1 week later
They were asked another series of questions
The critical question was "did you see any broken glass?"
The participants were not told the true aims of the study as they would focus on the critical part of the experiment (demand characteristics)
This is why the critical question was embedded in other questions, the other questions were to "throw them off the scent"
Experiment 2
Experiment 1
Participants estimated that the vehicles had been travelling fastest when the verb "smashed" had been used
Participants estimated that the vehicles had been travelling slowest when the verb "contacted" had been used
Table A
Table B
The findings show that participants estimated higher speeds in the "smashed" condition
The findings relating to the critical question suggest that participants in the smash question were more than twice as likely to report seeing broken glass than those in the "hit" condition
This matches what they found in experiment 1
Experiment 1
Experiment 2
The findings indicate that the form of the question can markedly and systematically affect a witness answer to that question
The findings from experiment 2 indicate that leading questions may cause an actual distortion in someone's memory of an event. This suggests that this effect is not due to a response-bias but that leading questions actually alter the memory a person has of the event
Overall conclusion
Overall conclusion
People's accuracy for reporting the details of a complex event is potentially distorted through the use of leading questions