The aim of Loftus and Palmer’s experiments was to investigate how information supplied after an event, influences a witness's memory for that event.
The participants in the first experiment were 45 students of the University of Washington.
They were each shown seven film-clips of traffic accidents. Following each clip, the students were asked to write an account of the accident they had just seen. They were also asked to answer some specific questions but the critical question was to do with the speed of the vehicles involved in the collision.
There were five conditions in the experiment (each with nine participants) and the independent variable was manipulated by means of the wording of the questions.
The critical question was ‘About how fast were the cars going when they ***** each other?'. In each condition, a different word or phrase was used to fill in the blank. These words were; smashed, collided, bumped, hit, contacted.
The dependent variable was the speed estimates given by the participants.
Speed estimates for the verbs used in the estimation of speed question
Verb Mean estimate of speed (mph) Smashed 40.8 Collided 39.3 Bumped 38.1 Hit 34.0 Contacted 31.8
The results demonstrated that the phrasing of the question brought about a change in speed estimate. With smashed eliciting a higher speed estimate than contacted.
A similar procedure was used whereby 150 student participants viewed a short (one minute) film which contained a 4 second scene of a multiple car accident, and were then questioned about it. There were three conditions and the independent variable was manipulated by the wording of the question.
50 of the participants were asked 'How fast were the cars going when they hit each other?’
50 of the participants were asked 'How fast were the cars going when they smashed…