To investigate how information provided to a witness after an event will influence their memory of that event
They used a lab experiment with 45 students which were split into 5 groups of 9
Each participant watched 7 video clips of staged crashes and answered a questionnaire about each one. They were all asked 'about how fast were the cars going when they _______ each other'
Each group was given a different verb to fill the gap, they ranged from smashed to contacted. Therefore the IV was the verb used and the DV was the estimate of speed given by participants
How the question was phrased influenced the participants estimate of speed, for example the estimate of speed for the verb smashed was 40.8mph and for contacted it was 31.8mph which is exactly 9mph difference.
The wording of the question did affect the estimate of speed, with the more severe sounding verbs producing higher estimates. Loftus suggested 2 reasons for why leading questions affect memory:
Distortion: the verbal label attached to the event by the question could have led to the participant cognitively changing their memory
Response bias: the participant is not sure of the exact speed and therefore adjusts their estimate to fit in with the expectations of the questioner