Despite the many studies investigating dishonest behaviour, the ecological validity in moral decision-making research is lacking. Many studies used paradigms of instructed lying and as a result the lying observed in these studies is different from more spontaneous forms of lying as it does not involve the voluntary intention to lie. Additionally, participants are not as motivated to behave dishonestly in instructed lying experiments as compared to real-world situations, in which dishonesty is more of an impulsive act and context-dependent (Giorgio Ganis & Keenan, 2009). In the absence of voluntary intention and motivation the complex executive functions associated with dishonesty might not be fully investigated (Sip, Roepstorff, McGregor, & Frith, 2008). Subsequently, studies using instructed lying paradigms did examine the deception-related cognitive conflict; inhibiting the truth to produce lies, but not the moral one; choosing self-interest and thereby sacrificing honesty (Panasiti et al., 2014). As a result, studies started to compare different types of lies and found that the neural regions and processes involved depend on the type of lie. Regions such as the ACC, the precentral gyrus, and the cuneus seem to be involved in spontaneous lies. By contrast, memorized-scenario lies recruit only the right anterior middle frontal gyrus (Giorgi Ganis et al., 2003).
Similarly, Yin, et al. (2016) found that in addition to shared patterns with instructed lying, there are some activation patterns sensitive to spontaneous deception. In this respect, simulated dishonesty in laboratory experiments cannot be considered as being the same as dishonesty in real-world situations. In this respect, more recent studies created new paradigms to study the neural mechanisms of dishonesty in a more natural way. In these new paradigms, participants are tempted to behave dishonestly in return for monetary rewards (N. Abe & Greene, 2014; Baumgartner et al., 2009, 2013; Bhatt, Lohrenz, Camerer, & Montague, 2010; Greene & Paxton, 2009; Sip et al., 2010, 2012; D. Sun, Lee, & Chan, 2015; Volz, Vogeley, Tittgemeyer, von Cramon, & Sutter, 2015). The advantage of these paradigms is that participants themselves decided whether to behave unethically or not, which also captures the moral conflict.
However, the findings from these studies are mixed and further research is needed. Simultaneously, when reviewing moral decision-making research an important distinction should be made between deception and cheating behaviour. Deceptive behaviour requires a direct interaction partner and occurs in a social setting (Zuckerman, Depaulo, & Rosenthal, 1981). It also requires a considered decision to deceive the interaction partner. On the contrary, cheating behaviour does not require a direct interaction partner and is, therefore, less interactive and less social. Since there is a difference between the concepts of deception and cheating behaviour, the underlying neural mechanisms involved may also be different. So far, most neuroimaging research focused on deception and almost no research has been done on cheating behaviour. This is surprising, because the most costly forms of dishonest behaviour, such as tax avoidance, are labelled as cheating rather than deception. Since the constructs of deception and cheating share neural processes deception research may be used for insights on cheating, however, the less interactive form of dishonest behaviour should be investigated more extensively.