piatok 21. októbra 2011

Loftus & Palmer

Elizabeth Loftus was born in October 16, 1944 in Los Angeles, California. She received her bachelor's degree in mathematics and psychology from the University of California, Los Angeles in 1966 and her MA (1967) and Ph.D (1970) in psychology from Stanford University. Psychologist Elizabeth Loftus has been particularly concerned with how subsequent information can affect an eyewitness’s account of an event. Her main focus has been on the influence of (mis)leading information in terms of both visual imagery and wording of questions in relation to eyewitness testimony.


To test their hypothesis that the language used in eyewitness testimony can alter memory. So, they aimed to show that leading questions could distort eyewitness testimony accounts and so have a confabulating effect, as the account would become distorted by cues provided in the question.

To test this Loftus and Palmer (1974) asked people to estimate the speed of motor vehicles using different forms of questions. Estimating vehicle speed is something people are generally poor at and so they may be more open to suggestion.

The estimated speed was affected by the verb used. The verb implied information about the speed, which systematically affected the participants’ memory of the accident. Participants who were asked the “smashed” question thought the cars were going faster than those who were asked the “hit” question. The participants in the “smashed” condition reported the highest speeds, followed by “collided”, “bumped”, “hit”, and “contacted” in descending order. When people were asked a week after viewing the film whether they saw any broken glass at the scene (there was none), people in the smashed group were more likely to say yes. Therefore, a leading question that encouraged them to remember the vehicles going faster also encouraged them to remember that they saw non-existent broken glass. The question appears to have modified the memory itself.

Conclusions: This research suggests that memory is easily distorted by questioning technique and information acquired after the event can merge with original memory causing inaccurate recall or reconstructive memory.

Experiment:

The participants were 45 students of the University of Washington. They were each shown seven film-clips of traffic accidents. The clips were short excerpts from safety films made for driver education. The clips ranged from 5 to 30 seconds long.

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.

Condition 1: 'About how fast were the cars going when they smashed into each other?'

Condition 2: 'About how fast were the cars going when they collided into each other?'

Condition 3: 'About how fast were the cars going when they bumped into each other?'

Condition 4: 'About how fast were the cars going when they hit each other?

Condition 5: 'About how fast were the cars going when they contacted each other?'

The basic question was therefore '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 entire experiment lasted about an hour and a half and a different ordering of the films was presented to each group of participants. The dependent variable was the speed estimates given by the participants.

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