Thesis title: The Truth Behind Lies: A Behavioural and Brain Imaging Investigation into the Role of Social, Emotional, and Interoceptive Factors in Dishonest Behaviour
The phenomenon of deception has been extensively studied, but some factors that influence its prevalence and underlie its neural activity have yet to be explored. This PhD thesis aims to address this gap in the literature by examining the effect of various factors on deceptive behaviour and exploring the neural mechanisms behind such behaviour. Study 1 investigated the brain regions involved in deceitful decision-making when there is a risk of getting caught (reputation risk). It found that the anterior insula and cingulate cortex were more active and had higher functional connectivity when making self-gain dishonest choices under risk, which suggests the need for increased cognitive control due to internal conflict between moral values. In individuals with a more self-centred moral code, these regions were less needed for making dishonest choices but more when making honest ones in a social context. Study 2 looked at how emotions (anger, gratitude, and happiness) affect deceptive behaviour and found that emotions have an impact on deceit depending on whether they make individuals self-focused or other-focused. Anger led to more self-gain lies, happiness led to fewer self-gain lies, and gratitude led to the lowest rate of self-gain lies. Study 3 investigated the connection between interoception and deception, using a Multi-level Kernel Density meta-Analysis (MKDA), and found that regions involved in interoception are part of the network implicated in deceitful decision-making. It proposes that interoception may contribute to deceptive behaviour by processing interoceptive inputs during dishonesty and comparing them to prior beliefs. Interoceptive manipulation tasks (e.g., restrictive breathing, balloon distension) showed increased involvement of high-level regions to control conflicting sensory information, while non-manipulation interoception tasks (e.g., heartbeat detection, breath detection) showed bilateral anterior insula processing incoming signals without conflict. Study 4 is a research proposal to compare interoceptive measures in the cardioceptive and respiroceptive domains and evaluate the relationship of these measures and deception by examining the impact of stronger resting-state connectivity between the anterior insula and salience network on interoception accuracy and deception.