Since time immemorial efforts have been made to devise methods of detecting falsehoods. For the sake of justice and security it is essential that one identifies liars. Personally I have been fascinated with the field of forensic psychology and understand the potential benefits of knowing how to detect a liar. Visualizing how the brain lies using functional MRI is a huge step in this direction. Studies have identified several brain regions that are activated when people lie as compared to when they are not lying. The current paper will look into neural substrates that underlie human deceptive behavior.
Prefrontal Cortex and prefrontal white matter
There is a huge body of research available to validate the role of prefrontal cortex in lying. Functional magnetic resonance imaging (fMRI) studies on neural correlates of deception have shown that the prefrontal cortex and the anterior cingulate cortex (ACC) were more strongly activated during lying than during telling the truth (Lee et al. 2002; Ganis et al. 2003). It has been suggested that frontal cortex plays a significant role in lying as it aids in planning. Self-control and attention (Bhattacherjee.,2017).
Functional magnetic resonance imaging(fMRI) studies on deception revealed that the prefrontal cortex and the anterior cingulate cortex(ACC) were activated more than during telling the truth (Ganis et al. 2003). The study further demonstrated that the aPFC had an active role to play in lies that were well rehearsed and built around a coherent story than in lies which were spontaneous and noncoherent. On the other hand, ACC was more active when the lying was spontaneous and not -memorized.
Another study that examined white matter volumes in four prefrontal sub regions using structural magnetic resonance imaging on 44 individuals out of which 10 were pathological liars, 14 antisocial controls, and 20 normal controls. Results revealed that liars had a relatively widespread increase in white matter in orbitofrontal, middle and inferior, but not superior, frontal gyri compared with antisocial and normal controls. Which reflects that an increase in white matter may predispose some individuals to pathological lying. (Yang, et al, 2007). A study which had more realistic lying tasks found prefrontal activation which was focused more in ventrolateral and orbitofrontal cortex as compared to superior frontal cortices (Spence et al, 2004). There is also evidence that over a period of time a lying pattern desensitizes our brains to the associated negative emotions and enhances a behavior of stating bigger lies (Garrett, Lazzaro, Ariely,& Sharot .,2016) .
Personality and Intelligence in Lying
Tendency to lie is something which is engrained in our personalities. We all have an attitude towards lying which manifests in different situations. Research has shown that personality disorders like OCD, Antisocial, histrionic, borderline and narcissistic are associated with lying ( Ford, King & Hollender., 1988).Pathological liers have shown structural changes in pre frontal cortex (Yang .,2005
)A case study showed that prefrontal impairment affects executive functions and Theory of Mind which predisposes an individual to pathological lying (Poletti, Borelli & Bonuccelli .,2011). A study conducted on 38 undergraduate subjects indicated that subjects with high energy and outgoing nature were more successful deceivers as compared to subjects who were apprehensive (,Riggio, R. E., Salinas, C., & Tucker, 1988) There is evidence to show that intelligence plays a role in lying where intelligent extraverts have a tendency to lie (Sarzyńska et al.,2017) and lateral prefrontal cortex is a global hub that furthers control processes which are essential for human intelligence(.Cole, Yarkoni, Repovš, Anticevic, & Braver, 2012). Individuals suffering from Parkinosns have personality traits such as industriousness, seriousness and inflexibility which are usually associated with honesty. Now has evidence which demonstrates that this honesty has neurobiological basis especially prefrontal hypometabolism.
Physiological and Chemical basis in lying
Lying leads to brain arousal level because of a catecholamine response that is triggered by the Autonomic Nervous System. The same system is also responsible for various other physiological changes like voice modulation, skin conductance changes etc. The most sensitive measure in laboratory studies of the detection of deception has been electrodermal activity (e.g., Orne, Thackray, andPaskewitz, 1972). Neuroendocrine hormone, testosterone, appears to been seen to be associated with behaviors which are involved in lying (Carney & Mason.,2010) .Research shows that testosterone increases ones tolerance for risk [Coates & Herbert.,2008] and an insensitivity to punishment [Dabbs Jr, J. M., Carr, T. S., Frady, R. L., & Riad.,1995] acts which can encourage dishonest acts.Cortisol has also been found to be linked with lying Cohen, S., Doyle, W. J., Turner, R. B., Alper, C. M., & Skoner, .,2003().