Eyewitness testimony

The following experiment is a modification of the Loftus & Palmer experiment. This measures the difference in responses in the 'smashed' and 'bumped' condition after participants are subjected to reading a passage describing a accident. 60 participants were selected out of which 30 were male and 30 female. Equal no. of participants of each sex were subject to both the conditions. The results supported the hypothesis that the mean score in the 'smashed' condition will be higher than that of the 'bumped' condition.


Eyewitness testimony plays an important role in the criminal justice system. Many cases have been given a judgement purely on the basis of eyewitness testimony. Numerous cases of mistaken identification have led to grave concern in the society. Not only does the government have to provide huge monetary compensations but the life of the convict and his family is very severely affected. It is at such times when one wonders how important it is to go on false evidence and punish the innocent for a crime and put society at peace until finding that the convict was innocent. This led to research in the loop holes of eyewitness testimony and how they can be avoided.

Kassin, Ellsworth & Smith (1989) suggested that there is a 5% chance that eyewitnesses tend to overestimate the duration of events and a 27% chance that the testimony is affected by how the questions are worded. Plenty of research was done by Loftus & Palmer but an experiment which played an important role was their study in 1974. Bird (1927) says that most people are inaccurate in reporting numerical details and the inaccuracy tends to be an overestimate. Loftus & Palmer decided to study the causes of these inaccuracies. Wording of a question plays an important role when eyewitness are questioned about a particular incident.

Loftus & Palmer used the concept of leading questions in their study. A question that by its form or content suggests a desired answer is known as a leading question. In their study they showed videos of an accident to the subjects and questioned them on it by changing a word in the question. They used the words 'smashed' or 'bumped' or 'hit' or 'collided' or 'contacted'. The mean estimation in 'smashed' condition was higher than the rest. Changes were made to their study and the following study was carried out.

This was done to see whether the same effects occur when people merely read about an incident. In this study participants were asked to read a passage and answer a question asking them about the estimation of the blood alcohol content. The change made was that in the passage and the question either the word 'smashed' or 'bumped' was used. The experimental hypothesis: The mean estimation of responses will be higher in the 'smashed' condition than the 'bumped' condition.

The results of this experiment support the experimental hypothesis. They signify that the construction of a question systematically affect the answer of the witness. Levene's test for Equality of Variances (as shown in appendix D) indicated that the likelihood of the population variances being equal in the case of the 'smashed' and the 'bumped' condition scores is 0.161. As this is more than 0.05 there is no significant difference in the variances of the two conditions, and therefore it can be assumed that they are equal. An independent samples t-test was carried out and it indicated that the results are significant i.e. the mean score in the 'smashed' condition is significantly higher than the 'bumped' condition.

It can be seen that when participants were asked to respond to the question they decided to take a higher figure in the 'smashed' condition since the impact of the word is much stronger. There were some extraneous variable which might have affected the results. Since all participants did not simultaneously carry out the task there can be a difference in the results e.g. capabilities of participants may vary with the time of day due to different routines.

In a replication of this study tasks should be carried out simultaneously. In the vignette given to the participants 3 figures were already given to explain the question. Participants could have replied one of these figures to finish the task faster. Most participants would have given a multiple of 10 since it strikes faster to the mind and hence would not have given a sincere thought to the question, causing a inaccuracy in responses.


Baddley,A. (1993). Your Memory: A User's Guide, UK: Penguin Books.

Eysenck,M.,Keane,M. (2001) Cognitive Psychology: A Student's Handbook, UK:Psychology Press.

Loftus,E. (1974) Reconstruction of Automobile destruction: An Example of the Interaction Between Language and Memory. Journal of Verbal Learning and Verbal Behaviour 13, 585-589.