Fmri Lie Ddetection

Topics: Functional magnetic resonance imaging, Magnetic resonance imaging, Brain Pages: 8 (2510 words) Published: March 1, 2013
Deception is employed by human beings primitively. It is a form protective mechanism that would enhance self or group interest or survival. Intentional deception is a commonly observed phenomenon in the real world. However, falsification is widely considered as negative by violation of expectation for society.

Deception includes several types of communications or omissions that serve to distort or omit the complete truth. There are various form of deception which includes lies, equivocations, concealments, exaggerations and understatements. The intention of deception differentiates between deception and an honest mistake.

Detection of deception is crucial in the modern legal systems as an assessment of the reliability of the participants in the process: accusers and witnesses, victims and suspects. In addition, a high reliable lie detection instrument could enhance national security investigation against the ever-increasing global terrorism threat. In private sector; identifying fraud is also of critical importance in the corporate world and in the insurance industry. Literature review

Studies have been made on deception detection using blood oxygenation level dependent (BOLD) fMRI technology. The task paradigms varies from forced-choice lies (Andrew Kozel et al., 2009); feigning memory impairment (Lee et al., 2002); and several variations of the Guilty Knowledge Test, including lying about having a playing card to mock crime modelling closer to real world application (Langleben et al., 2002). Some of the studies offer extra bonus monetary incentives to those who can successfully pass the test, in order to increase the emotional salience of the lying task.

Different experimental paradigms have been conducted, resulting differential patterns of blood flow in various brain regions reported. The most positive and consistence result are activation of certain prefrontal and anterior cingulate cortex regions are greater in the lie conditions relatively to the truth conditions. The studies hypothesized that these regions are activated when the subject is inhibiting the truth.

Most of these studies reported only the results of analyses of pooled data from a group of willing subjects. However, the method must be able to apply to individual for application in real situation. The BOLD fMRI techniques still have advantages over conventional polygraph methodology. For example, an innocent subject who suffered nervousness would not create a false result as it would by polygraph. Background

Objective methods for determining truthfulness have been sought for decades. Currently, the most widely used is a multichannel physiological recording also known as polygraph. However, the effectiveness of polygraph in detection is limited by the reliance on peripheral manifestations of anxiety which includes skin conductance, heart rate, and respiration. Shrewd liars could still fake testing behaviour paradigms once they understand and familiar with the design of the measure. Estimate accuracy range from a high of 95% to low 50% (Simpson, J. R., 2008).

Other measures of deception study, has seen using of scalp-recorded event-related potentials (ERPs) measured by electroencephalography (EEG) tools. ERPs can provide high time-based resolution which reflects the neuronal activity associated with a sensory, motor, or cognitive event. It is believed that the amplitude and latency of the P-300 wave of ERP have been associated with deception (Langleben, et al., 2002). Hence, by comparing the P-300 behaviour in various conditions, it could suggest that the cognitive differences between lying and truth telling could be associated with changes in brain activity. However, this method is inadequate because their source in the brain cannot be uniquely localized. Unlike polygraph and EEG, accuracy would be increased by applying Functional Magnetic Resonance Imaging (fMRI). It is suggested that it is impossible to fake cerebral...
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