Detecting Deception

Question 1

Motivation to deceive?

Answer 1

Lying is a common communication strategy (Bok, 1978, Zuckerman et al., 1981)
An adaptive strategy for survival
Honesty isn’t always best (Turner et al., 1975)

Cost /benefits

• Save face
• Avoid conflict
• Establish/maintain power
• Terminate relationship

Question 2

Susan Finch: If a person is lying you will see them….

You can tell if a person is lying, they will be……

Answer 2

Rubbing their nose/underneath their nose
Changes in the mouth
Artificial smiling
Pausing and stuttering
Eyes moving – going up and down and around
Finger over their mouth – contemplatin

Looking away from you (gaze aversion) - “Not eye to eye” 
Tremor in the lips
More hand movements
Jaw is “down”
Jaw is “tight”
Feet show nervousness

Question 3

Approaches to detecting deception

Answer 3

Physiological
- Polygraph - Peripheral nervous system (PNS)
-  Central nervous system, fMRI studies
Behavioural
- Reality monitoring
Evidential
- Interviewing

Question 4

Properties of lies…

Answer 4

• Affective - in content and/or impact
• Mental (‘cognitive’) load- To lie (depending on the lie) requires the maintenance of two worlds:
  The world you want the receiver to know and the one you don’t want them to know.
• Lies can be rehearsed: ‘scripted lies’. Creates a distinction between episodic experience and general knowledge
• Lies are often ‘embedded’ in the truth: Mixes external and autobiographical sources.

Question 5

Theoretical Perspective 1: Multi-Factor Model (Zuckerman, DePaulo, & Rosenthal, 1981):

Answer 5

Emotional reactions - lies are associated with guilt, fear & delight
Cognitive effort – lying requires extra mental effort
Arousal – Lying causes arousal and anxiety
Emotion influences behaviour

Question 6

Theoretical Perspective 2: Interpersonal/Behavioural Control Deception Theory (Buller & Burgoon, 1996; Burgoon et al., 1999)

Answer 6

During a face-to-face encounter, liars must accomplish numerous communication tasks simultaneously
Liars realise that observers pay attention, and so attempt to control their behaviour.
Try to behave in a manner that makes them appear credible

Question 7

Theoretical Perspective 3: Cognitive Load/Effort

Answer 7

Lying requires extra mental effort
- Make up the story  creativity
- Monitor their story to ensure it is plausible (Vrij, 2008)
- Adhere to everything the observer knows or might find out
- Remember earlier statements - consistency
- Avoid slips of the tongue  Automatic activation of the truth – lying is deliberate – Gilbert (1991)
Lying is associated with increased brain activity in the higher areas of the brain (Spence et al., 2004)

Question 8

Complex Relationship

Answer 8

Liars show emotion and cognitive load:
Emotional arousal increases eye blinks BUT cognitive load decreases eye blinks
Emotional arousal predicts an increase in certain body movements BUT cognitive load predicts a decrease as a result of neglecting body language
Emotions and cognitive load are not exclusively experienced by deceivers - truth tellers may display nonverbal behaviours typically associated with deceptive accounts
Behavioural control – subjective: depends upon personal what a senders believes to be a ‘credible’ non verbal display.

Question 9

Orienting Reflex Approach - Guilty knowledge test (GKT)

Answer 9

Mainly used in Japan & Israel
Based on the orienting reflex (Pavlov, 1927)
Occurs when someone is presented with a personally significant stimulus
Asked several questions concerning crime – told to answer ‘NO’
- compares physiological responses to multiple-choice type questions about the crime, one choice of which contains information about crime

If the offender is familiar with the info in one of the Qs
An orienting reflex occurs (Sokolov, 1963)
Decline in heart rate
Change in P300 brainwaves
Increased electrodermal activity

Question 10

Discriminating ‘real lies’

Answer 10

The Directed Lie Test (DLT).

compares physiological responses when the subject is told to lie deliberately to when they tell the truth. 


Question 11

Problems with the polygraph

Answer 11

Increased physiological rates and intensity caused by:
Factors other than fear of being caught lying
Faking to increase response to neutral qs
Evidence of lying in response to relevant questions:
Interpretation, up to the discretion of the examiner
Not a totally blind procedure (examiner knows event details/evidence)

Question 12

PNS: Pupil dilation

Answer 12

Webb et al (2010: Legal & Criminological Psych)
“Innocent participants showed larger increases in pupil diameter in response to probable-lie questions than to relevant questions. Guilty participants did not show differential responding to the question types.”

Cook et al (2012: JEP: Applied)
“Guilty participants had increased pupil responses to statements answered deceptively; however, they spent less time fixating on, reading, and rereading those statements than statements answered truthfully.”