Forensics - MaC - Witnesses

Forensics - MaC - Witnesses

1. Bruce: Internal and External features

   • George Ince
     • Tried for murder after he was identified by a witness who saw the attacker for at least 20 minutes
     • Discharged after he produced an alibi
   • Three Lab Experiments
     • Experiment 1
       • 30 staff and students (15 m, 15 f) from Sirling University, paid £2 to sort composites.
       • 10 celebrities and 40 composites produced by EvoFIT, E-FIT, PRO-fit and Sketch
         • Three sets - complete, external and internal
       • Participants tested individually on one of three conditions. They were asked to place each composite in front of the celebrity face in their own time until the task was completed
     • Experiment 2
       • 48 undergrad students from Stirling University (21 m, 27 f)
       • Photo array line-up with distractor faces, or foils to make the task more difficult
       • Composites were presented one at a time with the photo array and the ppt had to pick out the celebrity face from the array matching the composite
         • Composites were, again, either of internal or external features
   • Results
     • Experiment 1
       • Whole composites with external features were sorted similarly at 35 %, with internal features at only 19.5%
     • Experiment 2
       • Composited of external features (42%) were identified more easily than internal feature (24%)

2. Loftus: Weapon focus

   • Lab Experiment
     • 36 students from University of Washington, aged 18-31. Half recruited through an advertisement and were paid $3.50, the other half were given extra credit for their psychology classes
     • Two sets of 35 mm slides were shown with 18 slides showing people queuing in a Taco Time restaurant.
       • Control
         • Person B (Second in line) hands the cashier a cheque
       • Experimental
         • Person B pulls out a gun
       • Participants had to identify person B from 12 head-to-shoulder photos in a random sequence and were asked, in a questionnaire, how confident they were in their indentification
   • The concentration of a witness's attention on a weapon and the resultant difficulty in remembering other details of the scene