Lie detection

Question 1

Who invented the polygraph?

Answer 1

William Marston in 1938

Question 2

Study - accuracy of lie detection

Answer 2

Bond & DePaulo (2006)
Method - meta analysis of 380 deception studies
Results - overall accuracy of 54%; better at detecting honesty (61%) than deception (47%)

Question 3

What are three risks of police lie detection training?

Answer 3

Often less accurate but more confident after training
Dangerous decisions theory - initial judgments about suspect can affect how later information is interpreted (confirmation bias)
Investigator bias - training and experience increase tendency to believe person is lying

Question 4

Who devised the six basic expressive emotions? What are they?

Answer 4

Paul Ekman

Fear, anger, sadness, hapiness, disgust, surprise

Question 5

Study - cues of liars

Answer 5

Brink & Porter (2012)
Method - studied 78 emotional please to the public for return of missing relative; 1/2 of pleas by killer (lying)
Results - verbal cues: liars used fewer words, more tentative language (higher cognitive load); nonverbal cues: liars failed to show sadness, occasionally let happiness slip through

Question 6

What are four risks of relying on verbal/nonverbal cues?

Answer 6

Individual differences in expressivity
Cultural differences in expressivity
Makes neurotypical assumptions
Creates assumptions about victim integrity in court

Question 7

What are the four physiological markers of nervous lying?

Answer 7

Elevated heart rate
Elevated blood pressure
Elevated perspiration
Changes in breathing

Question 8

Study - lie detection wizards

Answer 8

O’Sullivan & Ekman (1991)
Method - tested lie detection ability of more than 12,000 people
Results - 42 wizards identified with accuracy of 80%; wizards can notice more cues and more subtle cues than the rest

Question 9

What are the three polygraph methods in increasing reliability?

Answer 9

Relevant/irrelevant test
Control question test (CQT)
Guilty knowledge test (GKT)

Question 10

What are the three kinds of questions used in the CQT?

Answer 10

Irrelevant questions
Relevant questions
Control (comparison) questions

Question 11

What are two weaknesses of the CQT?

Answer 11

High false positivity rate (20%)

Not standardized, subject to interpretation by examiner

Question 12

What are four limitations of the GKT?

Answer 12

Must have sufficient crime facts available
Culprit must know details
Crime facts must not be public knowledge
Time consuming, costly

Question 13

What is the major strength of the GKT?

Answer 13

Accuracy (95%) with very low false positives