1 A2 Psychology: Unit G543 Making a Case: interviewing witnesses

2 Unit G543: Options in Applied Psychology Forensic Psychology –Making a Case Interviewing witnessesInterviewing witnesses Interviewing suspects Creating a profile –Reaching a verdict Persuading a jury Witness appeal Reaching a verdict

3 Factors Influencing Identification Weapon focus refers to the concentration of a crime witness’s attention on a weapon and the resulting difficulty in remembering other details of the scene fixate their gazePerception experiments have shown that people fixate their gaze for longer, faster and more often on unusual or highly informative objects

4 Factors Influencing Identification Eye fixation data –The participant is filmed while looking at slides or a video clip and minute accurate measurements are made exactly where the eyes are scanning. –These measurements can then be plotted to reveal the gaze concentration

5 Interviewing Witnesses: Loftus et al (1987) Aim weapon focusTo provide support for the weapon focus effect when witnessing a crime Methodology A laboratory experiment

6 Interviewing Witnesses: Loftus et al (1987) Participants 36 students at University of Washington, aged 18 – 31 ½ were recruited through an advertisement and were paid $3.50 The remainder participated in exchange for credit in their psychology classes

7 Interviewing Witnesses: Loftus et al (1987) Procedure Participants were told it was a study of proactive interference 2 sets of 35mm slides were shown The 18 slides in each series showed people queuing in Taco Time restaurant In the control group, person B (2nd in the line) hands the cashier a cheque In the experimental condition, person B pulls a gun (the IV) All the other slides in both series were identical and shown for 1½ seconds DV measured by a 20-item multiple-choice questionnaire Participants were also given a line up of 12 head & shoulder photos in a random sequence, –asked to rate how confident they were of their identification on a scale of 1 (guess) to 6 (very sure)

8 Interviewing Witnesses: Loftus et al (1987) Results Answers to the questionnaire about the slide showed no significant difference between the two conditions Chance performance on the photo line up was calculated to be 8.5% In the control condition, 38.9% chose the correct person B (7 people) against 11.1% in the weapon condition (2 people) –statistically significant There was no difference in the confidence level of either group Eye fixation data showed an average of 3.72 on the gun and 2.44 on the cheque –also statistically significant

9 Interviewing Witnesses: Loftus et al (1987) Discussion The participants spent longer looking at the weapon and therefore had more difficulty in picking the suspect from the line-up –2 nd experiment, using the same procedure with another 80 psychology students, supported the findings This influence may be further enhanced in a real-world situation when a witness will be more aroused and is likely to have increased attention narrowing

10 Interviewing Witnesses: Loftus et al (1987) An unusual attack or one involving a weapon is going to affect the witness’s ability to create an E-fit of the attacker