To investigate the relative recognisability of internal and external features of facial composite ( e-fits )
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What are internal features ?
Eyes,nose,mouth,brow...
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What are external features ?
Head shape,hair,ears ...
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What method did Bruce use ? And how many experiments were conducted ?
Lab experiment and 3 were conducted
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How many and who were the pts in experiment 1 ?
30 staff and students from stirling university , 15 female and 15 males
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How many and who were the pts in experiment 2 ?
48 undergraduates at stirling university , all volunteers , 21 males and 27 females
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How many and who were the pts in experiment 3 ?
8 staff and students from stirling university , from computer science and psychology departments
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What was the procedure of experiment 1 ?
10 target photos of celebrities were used and 40 composite images created by e-fits were also used.There was 3 different conditions ; 1.composite was a complete face 2. composite only had internal features 3.composite only had external features.
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What was the procedure of experiment 2 ?
Pts were shown 1 composite at a time , along with a photo spread of faces which were either similar to the composite or very different to the composite.They were asked to pick the celebrity that matched the composite.
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What was the procedure of experiment 3 ?
They were asked to produce a composite of a target face
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What were the results of experiment 1 ?
Whole composites and those of external features were the easiest to recognise with 35% of pts getting the matching correct. Internal features proved the hardest with only 19.6% matching correctly
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What were the results of experiment 2 ?
Composites of external features (42%) were identified more easily than internal features (24%) and that was consistent across array type ( easy or hard )
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What were the results of experiment 3 ?
For both groups the external features were much better reproduced in the composites
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What was Loftus's aim ?
To provide support for the ' weapon focus ' effect when witnessing a crime
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What method did Loftus use ?
Lab experiment
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What is the independent variable ?
Whether person B has a gun or a cheque
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What is the dependent variable ?
The score on the multiple choice and the line up rating 1 - 6
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How many and who are the pts ?
36 students at university of washington , aged 18-31. 1/2 were recruited through an ad and were paid $3.50 , the remainder participated in exchanged for credit in their psychology classes
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What was the procedure ?
2 sets of 18 slides were shown , showing people queuing in a taco time restaurant. In the control group person B hands the cashier a cheque , in the experimental group person B pulls out a gun.All the other slides were identical and shown for 1.5 s
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How was the DV measured ?
Its measured using a 20 item multiple choice questionnaire , they were also given a line up of 12 head and shoulder photos in a random sequence and were asked to rate how confident they were of their identification on a scale of 1-6
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What were the results ?
Answers to the questionnaire about the slide show showed no significant different between the 2 conditions. In the control group 38.9% chose the correct person B compared to 11.1% in the experimental group. There was no difference in the confidence.
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What conclusions can we make ?
Pts spent longer looking at weapon meaning that it was more difficult for them to identify the suspect
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What was Fisher's aim ?
To compare the performance of experienced detectives before and after cognitive interview training and compare post training performance to a control group
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What method did Fisher use ?
Field experiment with actual interviews of real witnesses by serving police detectives
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How many and who are the pts ?
16 detectives from the robbery division in Florida , experienced 5 years or more
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What was the procedure ?
All 16 detectives taped several interviews over a 4 month period. After this the detectives were spilt into 2 groups - 7 went for four , 1 hour training sessions on cognitive interview. After this all detectives taped more interviews over 7 months.
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How were the results gathered ?
The interviews were transcribed and scored by independent judges. And the number of relevant , factual and objective statements were recorded
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What were the results ?
Comparison of pre and post training = 47% more info recorded in post training , with 6/7 of the detectives doing better post. Comparison of post and control group = 63% more info recorded in trained group.
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Other cards in this set
Card 2
Front
What are internal features ?
Back
Eyes,nose,mouth,brow...
Card 3
Front
What are external features ?
Back
Card 4
Front
What method did Bruce use ? And how many experiments were conducted ?
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