Experiment on eye witness testimonies

By Thea, Jody, Rachel and Pennie

Psychology experiemnt • Loftus and Palmer, two psychologists, interested in the accuracy of eye witness testimony after

witnessing a car accident, created an experiment of which they could see if leading questions distorted the accuracy of an eyewitness’ immediate recall. Loftus and Palmer’s experiment influenced the aim of ours, to observe the accuracy of eye witness testimony and with which we replicated their study with appropriate changes, adapted to our investigation. Loftus and Palmer showed their participants a short clip of a car crash on two separate occasions and afterward, gave them a questionnaire with specific questions about what they had watched. A critical question would vary the words used in order to test whether a participant’s eye witness testimony altered when they’d been lead to believe they’d seen something they hadn’t. Our investigation also showed a short film of a minor car accident and after, the participants would answer a short questionnaire. However the participants in our experiment were not observed in different conditions, nor did they take part in repeated measures. Our study allowed the two groups of participants to be split in the same condition as independent groups. We used a critical question which asked participants if they had seen broken glass from the impacted car or not. The independent variable differentiated between participants who were asked if they’d seen “any broken glass” to those who were asked if they’d seen “the broken glass”. We expected to see a change in results between the two groups of participants, specifically that the participants asked to recall “the glass” would be more likely to believe they had, indeed, witnessed that. It was appropriate to conduct a directional hypothesis in order to have an expected outcome to our study. Our investigation was to study the difference in the two groups and then to record the number of participants who answered “yes” to seeing broken glass in each condition.

Method

• For our experiment, first of all we had to find a suitable video clip of a car accident to show to our participants. To respect our participants and the Ethical Guidelines of psychological experiments, we made sure the clip we chose to use wasn't too violent and graphic, so our participants didn't become stressed or harmed in any way.

• When we decided on a suitable clip, we devised 2 similar questionnaires regarding events that happened in the video, changing the wording of 1 question to test the eye witness testimony of our participants. We wrote 6 questions in total, including ‘What was the colour of the first car you saw?’, ‘Was the person in the car a man or a woman?’, ‘Name as many characters of either number plate as you can’, ‘Were there any other cars on the road when the collision occurred?’ and ‘How fast do you think the swerving car was going when it collided with the other?’. For the 4th question, we added in ‘Did you see any broken glass?’ in which we changed the word ‘any’ to ‘the’, and used this as the question to test the eye witness testimony. We then printed out 10 copies of the questionnaire, 5 with the word ‘any’ used, and 5 with the word ‘the’.

• We then gathered 10 participants, and randomly gave them a card saying ‘1’ or ‘2’ in order to split them into two groups. Group 1 were given the questionnaire containing the question ‘Did you see any broken glass?’ and group 2 were given the questionnaire containing the question ‘Did you see the broken glass?’.

• Before showing the participants the clip, we read a short speech explaining what to do, their Right to Withdraw at any time, and the simple rules of our experiment (no talking, turn your questionnaire over when finished, etc).

• We then showed the participants the clip once and gave them as much time as they needed to fill in the questionnaire. When they had finished, we collected in their questionnaires, and read a debrief to them, explaining what we were trying to find out in the experiment, and answering any questions they may of had and listened to their opinions/comments of the study.

Results

• Condition 1 Condition 2• “Yes”3 0• “No” 3 6

• The results that we gained from our experiment were very different to the results that we were expecting. We predicted that the participants in condition 2, in which the phrase “the broken glass” was used, more participants would answer ‘Yes’. However the opposite occurred and participants in condition 1, in which the phrase “any broken glass” was used, more people said yes. This was unexpected because we thought that the use of the word “the” would lead out participant to think that there was broken glass when there wasn’t. However, when we analysed our results we can up with a few reasons as to why our results came out the way they did. Despite the fact we split the group using numbers pulled out of a hat, condition 2 was primarily boys. We thought that this could be significant because boys generally play more computer games, in which there is violence. Because of this, we thought that the leading question would not affect them as something like broken glass would generally go unnoticed by them.

Results

Evaluation • In our experiment, in which we based on one conducted by Loftus and Palmer concerning the

accuracy of eye witness testimonies, we actually found unusually and to the contrary to their findings, the opposite results. We anticipated that the participants who had the words ‘the’ is when asked if they saw glass, would answer yes that they did see broken glass (when there was none of the footage we showed them) however, we found that more of our participants answered yes to seeing broken glass when they had the questions with the word ‘any’ in it. We came up with some ideas about the reasons for our unusual results and why the response biased was not as Loftus and Palmer found by using a critical word.

• In our experiment, we only used ten participants and we thought that this was not enough participants to gain accurate results and that if we used more we may have had a better average of people answering yes when the word ‘the’ was used. And also, the participants, however we separated them randomly and gave out the questionnaires randomly, we realised that those who had the questionnaire with ‘any’ in it were all boys. And those who had the questionnaire with ‘the’ in it were all girls. We concluded from this that however there was no glass, because boy generally and stereotypically play a lot of video games and see a lot of violence and action in it, they may of from this altered their memory and though that they saw broken glass by making it seem more violent than it actually was.

• To conclude our experiment was a good way to allow us to conduct our own experiment even though we did not gather the information that we thought we would get, we believe that had we used more participants and has an equal amount of girls and boys doing each questionnaire – perhaps our results would of matched more closely those of Loftus and Palmer.