PSYC1004 Study Guide - Final Guide: Brodmann Area 10, Cerebral Circulation, Frontal Lobe
The Neuropsychology of Living
The Polygraph (the lie detector test):
• Used extensively in the past.
• Relies on changes in heart rate, skin conductance and blood pressure.
• These physiological markers change in response to stressful events.
• However, the following are also stressful events:
o Worryig aout eig harged with soethig you did’t do.
o Being hooked up to a machine and asked questions by police who think you are a homicidal
maniac.
• Conversely, it is possible to control responses like heart rate and skin conductance, eg: increased pain
will result in the same result, and the subject could be delusional.
• Therefore, polygraph tests are rarely used now.
• However, with the development of modern brain imaging techniques we should be able to observe
consistent neural signatures.
What do we know about the neuropsychology of lying?
• PET and fMRI measure blood flow in the brain.
• When a part of the brain is working in response to some event, blood flow to that part of the brain
increases accordingly.
• Believed to be better than polygraph because the individual can't regulate cerebral blood flow.
• Eg: Langleben et al. (2002) used the Guilty Knowledge Test (GKT) - normal participants were given a card
in an envelope and asked to lie in regards to whether or not they possessed a particular card. The
control condition was responses to questions that required a truthful response.
• Mainly the prefrontal cortex, frontal cortex and anterior cingulate. Areas of the brain known to be
involved in things like: dealing with conflicting information, and inhibiting responses.
• Eg: Kozel et al. (2005) - normal subjects asked to 'steal' a ring or watch and asked to lie about the
'watch' or 'ring' questions. Had an added motivation of getting $50 if they could deceive the
experimenter.
• Analysis: modelling the actual brain activation in one group of subjects and then determining the degree
to which they could predict brain activity in another similar group of subjects.
• Important parts: frontal, prefrontal and cingulate areas again.
• Eg: Abe et al. (2007) - dissociating the frontal activity: the act of lying, and the social/emotional
component to deceive.
• Subjects asked simple questions about their life. Were asked to tell the truth, lie, tell the truth, lie (but in
the last two conditions a confederate 'secretly' asked them to deceive the experimenter).
• The left dorsolateral prefrontal cortex showed a main effect of lie only, whereas the right anterior
prefrontal cortex showed main effects of both lie and dishonesty.
The P300
• An electrical brain signal that occurs as a response to external events (ERP).
• It is a measure of large populations of cells firing.
• Occurs about 300ms after the event.
• Responds to events that have novelty, relevance, salience, and are meaningful.
• Farwell et al. used a version of the GKT - subjects see a scenario then asked questions that are either
relevant, irrelevant, or probes which are information statements that only the subject could know about
the scenario.
• The P300 responds to the probe items.
• The logic here is that a subject under questioning will demonstrate a P300 to items that only they could
know, eg: that a special knife was used in the murder.
• Claims to be able to distinguish FBI agents purely on their P300 response when asked particular
questions pertinent to their training.
What about the criminal brain?
• Recent review of 15 articles over the last 10 years showing disturbing commonalities - decreased or
inappropriate blood flow in the inferior frontal cortex again.
• Subjects incarcerated.
• Various tasks - differences in brain activity reflected the different tasks.
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Document Summary
The polygraph (the lie detector test): used extensively in the past, relies on changes in heart rate, skin conductance and blood pressure, however, the following are also stressful events: These physiological markers change in response to stressful events: worryi(cid:374)g a(cid:271)out (cid:271)ei(cid:374)g (cid:272)harged with so(cid:373)ethi(cid:374)g you did(cid:374)"t do, being hooked up to a machine and asked questions by police who think you are a homicidal maniac. Conversely, it is possible to control responses like heart rate and skin conductance, eg: increased pain will result in the same result, and the subject could be delusional. Therefore, polygraph tests are rarely used now: however, with the development of modern brain imaging techniques we should be able to observe consistent neural signatures. Eg: langleben et al. (2002) used the guilty knowledge test (gkt) - normal participants were given a card in an envelope and asked to lie in regards to whether or not they possessed a particular card.
