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For many years now “Lie Detection Tests” have been in use though without full authenticity.The parameters that were used were physiological reactions such as heart rate, blood pressure, pupil dilation and skin sweat response to direct questions, such as “did you kill your wife?”
With advances inbrain scanning technologies and better understanding of the working of the brain, we are much closer to establishing if a person is lying or speaking the truth.The recent Neuroscience News edition of 06 August 2017 talks about the latest research in this area where a new technique may become almost be acceptable by courts as providing evidence of lying.
In this technique, electrical signals within the brain are scanned through the scalp by electroencephalography (EEG). These signals indicate brain responses known as the P300 signals to questions or visual stimuli. Theseresponse signals are assessed for signs that the individual recognises certain pieces of information or not. The process includes asking some questions that are neutral in content and are used as controls, while other questions probe for knowledge or awareness of facts related to the offence.
The P300 response typically occurs very fast within 300 to 800 milliseconds after the question or other stimulus. This fast response by brain indicates awareness or otherwise of the event and is compared to what the subject claims. If there is a discrepancy, it is clear that he is lying or concealing the fact. If the questions can be made sufficiently narrow to focus on knowledge that only the perpetrator of the crime could possess, then the test can accurately reveal if the subject is concealing knowledge of critical information.
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WE SHOULD NOT FORGET THAT PEOPLE MAY KNOWINGLY CONCEAL KNOWLEDGE OF FACTS RELEVANT TO A CRIME FOR ALL SORTS OF REASONS, SUCH AS PROTECTING OTHER PEOPLE OR HIDING ILLICIT RELATIONSHIPS.
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These reasons for hiding knowledge may have nothing to do with the crime. You could have knowledge relevant to a crime but be totally innocent of that crime. We need to look at the test as revealing knowledge or lack of knowledge of an event and not necessarily of guilt.
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