Week 7 - Deception Flashcards
What are the 3 key components in deception?
- intent
- no forewarning
- success is not relevant
What are the 3 types of deception?
- falsifications
- distortions/exaggerations
- omissions
What are 3 ways to (try to) catch a liar?
- physiological/formal techniques
- nonverbal/body language cues (believed and actual)
- verbal cues (content of the lie, active interviewing)
Who invented the polygraph?
invented by William Marston
What does the polygraph measure?
- heart rate
- blood pressure
- breathing (rate and depth)
- galvanic skin response
The polygraph detects physiological changes. This assumes that reactions are linked to:
lying
Expected changes in polygraphs include:
- increased skin conductance
- increased blood pressure
- decreased respiratory activity
- decreased blood flow to fingers
What are common emotional responses to lying?
guilt, fear, excitement.
In polygraphs, we look for behaviours linked to:
change in emotion
What is the control (comparison) questions technique? We are comparing responses for:
- neutral questions (establish baseline)
- relevant questions
- control questions
Does lying trigger a behaviour?
No - but it might trigger an underlying emotional process, which we will see in a polygraph.
What are some problems with the control question technique?
- assumes control (more reaction ) > relevant for innocent suspect
- assumes relevant (more reaction to these) > control for guilty suspect
- role of examiner (can’t scare suspect too much or too little)
- ethical question of deceiving suspects
What is the guilty knowledge test?
- questions re details that only guilty P would know
- several plausible alternatives for each question
- suspect gives same response to each
- if guilty, larger reaction to correct (recognised) alternative
What is one advantage to the guilty knowledge test, over the control question test?
better ethics than the control question technique.
The polygraph can be administered to a suspect using the control question technique. At the end, the police might say it looks bad at the end, even if they’re innocent they might confess. What is the main problem with this?
Even if the polygraph shows they’re innocent, they cannot use it in court. “They deceived me into confessing”, doesn’t cut it.
The guilty knowledge test is based on ___ not ____
recognition response, emotion
Responses in the guilty knowledge test are triggered by:
Personally relevant stimuli (e.g., hearing own name).
What happens in the guilty knowledge polygraph test when personally relevant stimuli is triggered?
increase EDA, decreased heart rate
The guilty knowledge test is limited to cases where:
- guilty suspect has the relevant knowledge
- innocent suspect doesn’t
Claims of polygraph accuracy is up to:
But these are:
99%, dodgy stats (if 1 person is lying out of 100, you still got it 99% accuracy).
Control question technique (when it makes a mistake) tends to:
Classify an innocent person as guilty. (prone to false positives)
The guilty knowledge technique (when it makes a mistake) tends to:
Classify a person as innocent when they’re not. (prone to false negatives)
What are the methodological issues with polygraph studies in the lab?
stakes may not be high enough
What are the methodological issues with polygraph studies in field studies?
No way of knowing if really guilty
