Lecture 5 Detecting Deception – Physiological Cues

What are the five main reasons people lie?

To gain personal advantage • To avoid punishment • To makeapositive impression on others • To protect themselves from embarrassment/ disapproval • For the sake of social relationship

What are the types of lies according to Depaulo et al 1996?

Outright lies, exaggerations, subtle lies.

What did DePaulo’s dairy study find?

Found that college student told lied 2 x a day and community members 1 x lie
Frequency depends on personality, gender, situation and the people to whom the lie is told,

What to do note about lying variation?

Looks like the majority of lies come from a smaller percentage of people.
Evd => serota et al (2010) - 60% of participants had not lied in the last 24 hours - but 5% of participants told 50% of lies
Evd => Smith - 23% reported no lies, but 90% of text contained lies.

What did Markowitz et al find about lying in face to face vs. digital communication?

Selfreports - most lies in synchronous communication (F2F, phone and video changes)
Large differences between individuals, average is 1 lie a week.

What are the three broad categories to detecting lies

physiological cues
Behavioural
cognitive .

What is the premise for the polygraph?

As lying is more stressful than telling the truth, therefore, we can detect lying by detecting ‘stress’ in physiological changes e.g skin responses, sweating etc.
Note that polygraph is NOT a lie detector, the same response may not actually indicate a lie could indicate other emotions. E.g shame, anger, fear

Describe a brief history of the polygraph?

Idea was a proposed by criminologist Lombroso in the 1800s, widespread in the U.S, 1 million test, mostly used in workplaces up until bans. Not used in the courts in the Aus, UK or most of the Europe.
U.S use it ‘investigatively’

What are the forms of the polygraph tests?

Original - Relevant-Irrelevant Question test
Modern
The Control Question test
The Guilty Knowledge test.

Describe the Relevant-Irrelevant Question test?

Relies on the idea that the guilty will respond more strongly when lying about the relevant question. PROBLEM - even an innocent person know which are relevant questions and will worry about the important question → leads to a lot of false positive errors.

Describe the Control Question Test?

Includes questions that an innocent and guilty person would both find stressful or embarrassing to answer. This will allow for a better baseline to compare with actual lies. There are five phrases to this test. CQ related to issues involved to the case but not the crime itself
in P1 the formulation of questions are discussed with suspect
In P2 the subject is convinced that the polygraph is able to detect lies
In P3 the questions are asked several times overs
In P4 is interpretation - global - or a numerical scoring approach. (if control q > relative = truth and visa versa.
In P5, tell the suspect that they failed the test.

What are the critiques of the CQT?

formulation of control question can never really be unbias
Scoring is not sufficiently quantified
Ethics - strong elements of deception and infallibility of procedure is assumed.
Assumptions about Why should an innocent person show a stronger response to control? Why should the guilty show a stronger response than relevant?

Describe the Guilty knowledge test?

Aim to test if the suspects possess knowledge that only the guilty would have, based on the idea that recognition of guilty knowledge will result in arousal, compared to that of an innocent person. NO LONGER LOOKING AT THE TRUTH.

Explain Lykken as an example of the Guilty Knowledge test?

Lykken argued that you can use the polygraph test as a way to determine guilt by measuring arousal according to the options presented that only a guilty person should know.
They cite specifically the OJ Simpson case.

What are the limitations and precautions to note about the guilty knowledge test?

Can only be used in cases where details are known to police
Assumes that the perpetrator knows all the details.
Suggest that the examiner should be unaware of the correct answer - as suspects may ‘detect’ the correct answer from the examiner.
Suggests that alternatives must be presented as equally arousing for an innocent person.

What do lab studies say about the CQT and GKT?

CQT - large amount of correctly guilty, but lots of incorrectly guilty
GKT - large amount of correctly guilty, but not a lot of incorrectly guilty.
Note that lab studies are limited by the lack of ecological validity.

What to note about field studies and CQT and GKT?

It is very difficult to have any tests that show what is true or not true due to lack of actual ground truth.

What did Ginton et al (1982) do?

Enlisted 21 officers to take a test, given a cheating opportunity, all were suspected and asked to take a polygraph. CQT was used. Found that with the polygraph 7/13 innocent people were identified. Without the polygraph 11/13 innocent people were correctly identified.

What did the BPS review find?

Found that
CQT - when guilty 80-90% correctly identified. , innocent 50-80% correctly identified.
GKT - when guilty 40-70% correctly identified. , innocent 98% correctly identified.

What did Ginton 2013 do?

Enlisted a pair of participants of which one had to be lying and one had to be telling the truth. Polygraph control question tests are analysed separately and look at how often one is found to lie or both or both truth.
The method found that the CQT has estimates of 83% in accuracy. Still sig critique due to some statistical assumptions

What are some countermeasures to the Polygraph?

Floyd Buzz Fay, was able to train and recruit inmates to pass a CQT. Forcing a stressful response during the control allowed for them to pass the test.

What were the general conclusions off the BPS report?

Accuracy is mixed

Explain the use of the polygraph with sex offenders?

from 2014 to 2022 , the UK has trialled the use of polygraph amongst all serious sex offenders, offenders may be required to be tested every 6 months as part of their conditioning surrounding their response.
Based on 2012 research suggesting that the testing allows for further protection to the community as offenders come to reveal more information around their management.

What does Aldert Vriji say about the use of polygraph amongst sex offenders?

‘Such tests lack support in the scientific polygraph community,’ he said, adding
that he believes it would be better for the police to be trained in techniques that aren’t ‘at theoretical and inaccurate’.