The words used to question witnesses matter

A widely known research article, by two psychologists from the University of Washington, confirms the view that, "questions asked subsequent to an event can cause a reconstruction in one’s memory of that event". Elizabeth F. Loftus & John C. Palmer, Reconstruction of Automobile Destruction: An Example of the Interaction Between Language and Memory, 13 Journal of Verbal Learning and Verbal Behavior 585, 585 (1974), available at: https://webfiles.uci.edu/eloftus/LoftusPalmer74.pdf .


This study tested whether or not how fast people would guess cars involved in an accident were going would change based on the verb used to describe the collision. Participants were asked to answer one of these five variations on a question about the cars' speed:


- About how fast were the cars going when they smashed into each other?

- About how fast were the cars going when they collided into each other?

- About how fast were the cars going when they bumped each other?

- About how fast were the cars going when they hit each other?

- About how fast were the cars going when they contacted each other?


The speed estimates varied directly with the strength of the word that was used:



A second set of people was shown films showing an auto accident, and different subsets of participants were asked either:

- About how fast were the cars going when they smashed into each other?

- About how fast were the cars going when they hit each other?

. . . or not asked about the cars' speed at all. A week later the group was asked if they had seen broken glass in addition to a list of other questions about the accident. The films did not show any glass breaking. The answers of the three groups varied according to how they were questioned a week earlier:



The study also showed how poorly people estimate speed regardless of the language that is used. Four films showed one collision at 20 mph; one at 30 mph; and two at 40 mph. The participants guessed the speed of the cars in each film to be between 35-40 mph.