Interviewing Witnesses

Aim: to investigate the recogonisability of internal and external facial features.

Procedure:

Experiment 1: Pp's were given pictures of 10 celebrities of which they had to match to the correct composite image. 42% of whole composites and external features were sorted correctly. Only 19.5% correct of internal features.

Experiment 2: Used a photo line up where they had to identify the celebrity composites from the array. External features indentified 42% of the time compared to only 24% internal features.

Conclusion: External features are more important for facial recognition meaning faces are processed holistically.

Aim: provide support for the weapons focus effect when witnessing a crime.

Procedure: Pp's were shown slides of a series of events in a resturant. For both groups all slides were exactly the same however the control group a person in the que hands a cheque to the cashier, however in the experimental group a gun is pulled out. Pp's then given a questionaire and also shown 12 photos and had to rate how confident they were that they were the criminal.

Results: In control group 38.9% made a correct identification however experimental group only 11.1%. Eye fixation data also showed a higher fixation time on the gun than the cheque.

Conclusion: Participants spent longer focusing on the weapon and therefore had trouble identifying suspect in a line up.

Aim: To test the cognitive interview in the field.

Procedure: Detectives were asked to record a selection of their next interviews using standard techniques. They were then divided into two groups and one was tought the CI techniques the other was a control. They then recorded more of their interviews which were then analysed by a team who were blind to the conditions.

Results: After CI training detectives elicited 47% more information than before and 63% more than the other group.

Conclusions: CI techniques do seem to work, more information is gathered. This could help police solve more crimes.