Honesty is a fundamental moral value that is ranked highly across cultures (Engelmann & Fehr, 2016), yet, people lie for many different reasons and quite often for self-serving goals (Yin & Weber, 2018). Dishonesty is an essentially social act with poorly understood neurobiological correlates (Sip et al, 2012; Langleben et al, 2005). Our study will explore the brain regions responsible for successfully executing a lie and will look at how the risk of losing our social status modulates this activation. For this, we will use the Temptation to Lie Card Game (TLCG adapted from Panasiti et al. (2011)). There will be three main conditions: 1. participants have the choice to lie or not and anonymity is assured, 2. they have the choice and there is a 75% risk that the opponent finds out about the choice and 3. the participant is instructed to lie or tell the truth. A 3T Siemens fMRI scanner will be used for neuroimaging. First-level analyses will be done by using a general linear model with each condition as a regressor and trial number and reaction times as parametric modulators. At second-level analyses, a flexible factorial model will be used. Behaviourally, we expect more lying when anonymity is assured, slower response times for lie-decisions versus truth-decisions and we expect that over time lying becomes easier ('Slippery slope') in both spontaneous conditions. We expect activation, especially in the frontal regions. When reputation is at risk, we expect more activation in the ACC. Moreover, we expect that individuals who are more dishonest have decreased ACC activation and that over time ACC activation diminishes in all individuals.
Numerous previous fMRI studies have found regions in the brain that correspond with lying versus truth-telling. In those studies, the paradigm was to instruct participants to lie. In day-to-day life, however, people lie more often in a spontaneous manner. Only very few have explored the difference in voluntary lies and instructed lies. They found very different regions responsible for these two types of lies. That is why our study will include both spontaneous lying (participants get to choose between lying or telling the truth) and instructed lying (they will be instructed to lie or tell the truth).
Merely one behavioural study (Panasiti et al. 2011 ) found how our social reputation plays an important role in our decision to lie. However, to date, there is a lack of imaging studies exploring the neural correlates of this factor. With the use of functional magnetic resonance imaging, we can have the best spacial representations of where these lying processes take place in the brain, which neural networks are used, how brain activity is influenced by the different conditions, how this is modulated by time and how this activity differs between more honest and more dishonest individuals. More specifically, we will use relatively new analysis techniques with SPM12 in Matlab, under which parametric modulations of time and reaction times, different general linear models, ROI analyses and functional connectivity.