Vrij And Mann: Police Ability To Detect Lies

Question 1

Sample

Answer 1

Study1 interviewee was a convicted criminal

Study2 59 male 6 female police officers, West Sussex

Question 2

Aim

Answer 2

To investigate behaviour of a suspect telling lies during police interviews and assess the accuracy of police in detecting lies

Question 3

Background

Answer 3

Best signs of lying:
Persons voice 
Unconscious language choice 
Lack of key details
Recall minute details that truth tellers forget
Increase pauses
Don't describe feeling

From ‘the curious science of everyday lives’
Wiseman,r

Question 4

Study 1- procedure

Answer 4

Suspect(later convicted for murder) video taped in interview
He denied involvement but hair found in car, later confessed but continues to lie

6 fragments of interview isolated and coded for 12 behaviours (smiling, speech rate)
Observers didn’t know if truth or lie

Question 5

Study 2- procedure

Answer 5

Fragments shown to 65 police officers (before and after confession)
Asked:
Lying, tense, controlling his behaviour, thinking hard
Wrote down behavioural cues

Question 6

Study 1 results

Answer 6

In pre confession, long pauses, spoke slowly, more speech disturbance

In confession interview he showed similar patterns when he was lying compared to telling truth

When lying he had to think hard and when telling truth he controlled behaviour

Question 7

Study 2 results

Answer 7

Overall accuracy 64%

Detecting truths 70% lies 57%

Large individual differences

Their that were better looked at more subtle cues e.g speech rate

Question 8

Conclusions

Answer 8

Murderer contradicted common belief that liars behave nervously

However he had previously been interviewed before trying hard to control fidgeting

Police officers better at judging truths

More training required