Measurements of Accuracy of Eyewitness Testimonies Essay

Custom Student Mr. Teacher ENG 1001-04 7 September 2017

Measurements of Accuracy of Eyewitness Testimonies

This study was designed using an account of a car accident. The aim was to measure the affect of re-wording a single sentence, on the estimation of how much alcohol was in the bloodstream of the driver. 20 undergraduate participants (10 male and 10 female) all with clean licences were used. They were randomly given a vignette describing the car accident, where half the subjects read that the driver ‘smashed into’ a garden wall, and the other half read that the driver ‘bumped into’ the garden wall. Participants were required to read the vignette and then estimate how much over the British legal alcohol limit the driver was, for example, 200% indicates that the driver was twice the limit, 110% would mean he was 10% over and 50% would mean he was half the limit.

The hypothesis predicts that those who received the vignette stating the driver ‘smashed into’ the wall are more likely to estimate a higher limit, than those who read that the driver had ‘bumped into’ the wall. The results of this investigation show that the mean estimation for those in the ‘smashed into’ condition (143%), was significantly greater than those in the ‘bumped into’ condition (108%), where p<0.05. This means that the experimental hypothesis was accepted, and the null hypothesis was rejected. Furthermore, these results gave further support for work done by Loftus and Palmer (1974) on leading questions, who showed that slight manipulations in questions can alter eyewitness testimonies.


The increasing demand for accurate and detailed evidence in today’s society means that there is a greater dependence on eyewitness testimonies. However, the idea that we are capable of recalling the exact details of a past event has been criticised and contradicted by a number of psychological studies. This investigation aims to measure the accuracy of Eyewitness testimony and discuss the relevance and implications of these findings in today’s society.

In October 1992, an El Al aeroplane crashed into an eleven-story apartment building, due to losing its engine after takeoff. The crash received masses of media coverage, however footage was never actually shown because the incident was never filmed. In a study about the crash by Crombag et al. (1996), 193 subjects were asked if they saw the plane hit the building. Astonishingly, 55% said that they had seen the crash, and 59% claimed that the fire started immediately on impact. A follow-up study showed that 68% of subjects said that they had seen the crash, and 67% said that they saw the plane hit the building horizontally, when in reality the building was hit vertically.

This study demonstrates that our memories are not entirely reliable. Another experiment by Loftus and Palmer (1974) shows how memories can be corrupted when presented with contradictory external stimuli. The aim was to investigate the effects of leading questions on the accuracy of speed estimates and perceived consequences of a car crash. In one laboratory experiment, subjects were shown seven films of traffic accidents (5-30 seconds long), and then asked to answer specific questions about the footage. The independent variable was the critical question, “About how fast were the cars going when they  (into) each other?”, where the words ‘hit’, ‘smashed’, ‘collided’, ‘bumped’ or ‘contacted’ were randomly inserted into the gap. Results showed that the mean speed estimate when the word ‘smashed’ was used, was higher (40.8) than ‘collided’, ‘bumped’, ‘hit’ and ‘contacted’ (31.8) respectively.

In a second experiment each subject was shown a short film that showed a multiple car accident. Loftus and Palmer asked 50 subjects, “How fast were the cars going when they hit each other?”, and 50 subjects were asked the same question with the word ‘smashed’ substituted instead of ‘hit’. A control group of 50 subjects were not interrogated about the speed of the vehicles. The subjects were then asked to return a week later and without re-viewing the film, answered a series of questions about the accident. In this case the critical question was, “Did you see any broken glass?”.

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  • University/College: University of California

  • Type of paper: Thesis/Dissertation Chapter

  • Date: 7 September 2017

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