Memories are easily manipulated by the questions used to recall the memories.
Lawyers and courts recognize the power of the leading question—a question that by either its form or content suggests to the person answering the question the desired answer (Loftus & Palmer, 1974). Psychologists took this known phenomenon a step further by demonstrating that such leading questions can alter memories putting serious doubt on the veracity of eyewitness testimony.
In the first experiment, 45 students were showed seven brief film clips of car accidents. Following each film, nine of the subjects were asked, "About how fast were the cars going when they hit each other?" The rest of the students were split into similar size groups and asked the same question, except that the word hit was exchanged with either smashed, collided, bumped, or contacted. Would there be a difference in reported speed?
In the second experiment, the researchers wanted to know if the phrasing of the question (in this case, the changing of a single word) could conjure a false memory about the accident. One hundred and fifty students were shown a video of an accident. Fifty students were asked the same "hit" question, another fifty were asked the same "smashed" question, and fifty were not asked any question about the speed. A week later, the students were asked a series of questions, one being, "Did you see any broken glass?" There was no broken glass in the video. Would the students that were asked how fast the cars were going when they smashed into each other be more likely to report seeing broken glass?
In the first experiment, the average speed estimated was significantly correlated with the verb used:
smashed = 40.5 mph
collided = 39.3 mph
bumped = 38.1 mph
hit = 34.0 mph
contacted = 31.8 mph
The way the question was phrased changed the subject's perception (memory) of how fast the car was going by as much as 21%.
In the second experiment, out of the fifty subjects who were not asked about the speed of the cars, 6 reported seeing broken glass. Out of the fifty who were asked about the speed using the word hit, 7 reported seeing broken glass. Out of the fifty who were asked about the speed using the word smashed, 16 reported seeing broken glass.
It is possible that students are more susceptible to influence, especially if a question is asked by an authority figure, although this is speculation.
It is important not to read too much into these results. While the phrasing of the question can alter the memory, the effects are limited.
This is a technique that can be used to get the answer desired. Like all cognitive techniques, they can be used for noble purposes or for manipulation, so beware.
This research and similar research by Loftus has had significant impact on the criminal justice system when it comes to eyewitness testimony.
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