Understanding the neural basis of deception versus truth-telling

• Main Author: Leow, Dayton Wei Yang
• Other Authors: Annabel Chen Shen-Hsing
• Format: Thesis-Doctor of Philosophy
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Social sciences::Psychology
• Online Access: https://hdl.handle.net/10356/161752
• Institution: Nanyang Technological University

An accurate and reliable means of deception detection is of paramount concern to the law enforcement and national security agencies. Traditionally, behavioural and physiological cues have been used to detect deceptive responses. However, many of these measures commonly associated with deception reflect anxiety and fear, rather than deception per se. In recent years, researchers and practitioners have turned to neuroimaging techniques to examine the mental processes underlying deception for greater precision. Converging neuroimaging evidence has revealed functional involvement of the prefrontal cortex (PFC), anterior cingulate cortex (ACC), insula, and possibly subcortical regions during deception. The activation of these brain regions suggests the involvement of a myriad of mental processes, namely executive function, cognitive control, conflict monitoring, and emotions processing, when individuals lie. However, majority of these neuroimaging findings and interpretations are derived from studies that are experimentally contrived and have limited internal and ecological validities. This may have contributed to the contradictory/unexpected findings reported by past studies. Although, there have been abundant studies on deception, the neural underpinnings and mental processes related to truth-telling remain elusively unknown. Therefore, it is clear that an ecologically and internally valid test and neuroimaging investigations into real-world spontaneous deception and truth-telling are much needed to advance this field of research. To address the abovementioned research gaps, this thesis endeavours to uncover the neural basis underlying the mental processes of deception and truth-telling with two studies. In Study 1, a meta-analysis of past neuroimaging findings was first conducted, using the activation likelihood estimation (ALE) method, to distill the neural substrates of deception versus truth-telling that would be consistently observed across past studies. The deception versus truth-telling ALE map revealed particularly the PFC subregions, inferior parietal lobule, supramarginal gyrus, insula and caudate to be significantly activated. On the other hand, only the insula was significantly activated for the truth-telling versus deception ALE map. These findings offered insights to the potential mental processes involved that are specific to deception and truth-telling. Results from this present meta-analysis provided the brain regions of interest that are specific to general deception and truth-telling, and served as a guide for the subsequent empirical study (Study 2). Study 2 examined the neural correlates of high versus low stakes deception and truth-telling pertaining to a mock crime scenario resembling real-world setting. Participants performed a mock crime prior to undergoing a fMRI task that is sensitive to detect spontaneous deception and truth-telling. Functional scans of 50 participants (28 in the high stakes condition and 22 in the low stakes condition) were analyzed for (a) whole brain functional activation and (b) functional connectivity among the brain regions of interest. Significant activation particularly in the dorsolateral, ventrolateral and medial PFC, cingulate, insula and dorsal striatum for real-world spontaneous deception contrast was revealed. Real-world spontaneous truth-telling contrast showed increased activation in the prefrontal cortices, posterior cingulate and parahippocampus. Functional connectivity results uncovered a network connectivity among bilateral medial PFC, left ACC, and right orbitofrontal cortex, which supports a cingulo-prefrontal network as a viable neural network for real-world spontaneous deception contrast. Considering the above findings, it is plausible that two mental processes are potentially critical for prevaricators to lie spontaneously and successfully, namely (a) response/performance monitoring and regulation, and/or (b) emotion processing and regulation. This thesis has provided a comprehensive examination on the neural underpinnings of the mental processes specific to deception and truth-telling under an ecological mock crime environment. Notably, the functional involvement of PFC subregions and ACC, and their functional connectivity, suggests the involvement of response manipulation and emotion regulation to be vital for successful spontaneous deception that is analogous to the real-world. The present findings with maximal ecological and internal validities under a contrived situation helped to extend the current theoretical knowledge of spontaneous deception and truth-telling in real-world context. It can also potentially guide future tool construction that would complement existing lie detection methods for a triangulated credibility assessment.