It makes evolutionary sense (Trivers, 2013) as lying to ourselves raises self esteem and it can give us the edge in things such as hunting
Detecting deception could also help us evaluate friends and foes
What are the types of deception?
Granhag & Hartwig (2008)
Falsification (everything reported is false)
Distortion (the truth is twisted to match the aims of the liar)
Concealment (the liar holds back some of the truth)
What is the emotional approach to lying?
Lying generates emotions different to truth telling such as the fear of being caught
These cause behaviour affects such as sweating, curling of the mouth etc
What is the content complexity approach to lying?
Zuckermann et al (1981)
Lying is more cognitively demanding than telling the truth
This cognitive effort reduces the number of gestures and changes behaviour
What is the attempted control approach to lying?
People are aware that the cognitive task of lying causes them to give off cues so they attempt to counteract this by acting normal
Do people behave differently when lying?
Yes (DePaulo et al, 2003)
120 samples and over 150 behaviours analysed
There are limited robust and reliable cues to deception
Liars tend to be more tense and have more dilated pupils and higher voices
The stories of liars are less vivid and contain fewer facts
Only students and mock crimes were used so this is pretty much all bullshit, good job
Have there been any studies into liars that haven't used students like retards?
Yep (Klaver, Lee & Hart, 2007)
Looked at nonverbal deception cues in Canadian prisoners
Asked to give a true account of the crime they committed and to make a false story about an imaginary one
Didn't display different rates of body movement when lying (nonverbal behaviour is usually reduced in non-criminal liars)
Spoke fewer words and showed more head movements but more psychopathic offenders spoke more faster and with more words
Vrij & Mann (2001) looked at nonverbal behaviour of murders before confession
When lying they spoke more slowly and with more pauses, this was also found in Mann (2002)
Who make the best lie catchers?
Average accuracy of 'lie detectors' is 54% (Bond & DePaulo, 2006), chance is 50%...
Expert lie catchers are similarly accurate to laypersons (45-60%)
Confidence is unrelated to accuracy (Vrij, 2004)
These are under lab conditions though, and they might be better in real life
What are the major cues to deception?
Gaze aversion is the most frequent
Speech disturbance such as pausing and stuttering (also common signs of nervousness though so could just be a nervous innocent person)
Liars aren't more nervous than truth tellers
The most effective human lie detectors are the ones who hold the least stereotypical views on lie detection (Mann et al, 2004)
What traits do liars show in Linguistic enquiry and word count?
Fewer first person pronouns (to dodge blame and distance themselves)
More angry, hostile and sad words due to guilt
This method is about 60% accurate in non forensic settings
Verbal leakage, things such as accidentally referring to a missing person in the past tense
Adefence that places the defendant at the relevant time of the crime in a different place than the scene involved and so removed therefrom as to render it impossible for one to be the guilty party” (Nolan, 1990, p. 71).
Ideally corroborated by another person and physical evidence
What makes a good alibi?
Person or Physical
Physical is much more effective and harder to fake (security feeds etc)
People are not always believable, however the average person does not appear to doubt whether they were mistaken in seeing the suspect or not (Olson & Wells, 2004)
People are much more likely to lie than hard evidence, however
What is the PEACE model?
Clarke & Milne (2001)
Plan and prepare
Engage and explain
Account, clarify and challenge
What happens in the planning phase of the peace model?
Prepare a plan
Familiarise yourself with the case file
Know the characteristics of the interviewee that could come in handy during the interview
Consider the questions you want to ask
What happens in the engage and explain phase of the peace model?
Introduce yourself and inform the suspect of the allegations
Tell them their rights
Outline how the interview is going to go down
Build up a rapport with the suspect
What happens in the account, clarify and challenge phase of the peace model?
Let the suspect give a full explanation from their point of view without interruptions
Probe the account
Challenge and clarify any inconsistencies
What happens in the closure phase of the peace model?
Sum up their side of the story
Respond to any remaining questions
Inform the suspect of the next steps
Exchange contact info
What happens in the evaluation phase of the peace model?
Evaluate the information you have received
Critically reflect on your own performance by watching tapes of the interview
Seek feedback from others
PEACE or REID?
PEACE emphasises and enforces ethical practice and is not based on detecting deception
No coercion and is confession orientated
70% of interviewers well trained in PEACE got at least a comprehensive account of events with 20% getting full confessions (Bull, 2010) upon review of 142 interviews
BUT only 5% of novice peace users got a full confession