Despite decision-making has been extensively studied in Parkinson’s Disease (PD), much less is known about moral decision-making in PD. Two studies (Abe et al., 2009; Mameli et al., 2013) found a behavioral pattern of “hyper-honesty” in PD patients but the employed behavioral paradigms were not ecologically-valid (patients were instructed when to lie and when to tell the truth), were not “social” (lies and truths were not directed toward another individual) and the medical status of the patients (on versus off dopaminergic medication) was often mixed. Recent research also pointed out a role of Sense of Agency (SoA, the feeling that we are in control of our actions and of their consequences in the external world; Haggard et al., 2002) in moral responsibility for action. In particular, stronger intentional binding - a compression in time perception between voluntary actions and their effects that is considered an implicit marker of SoA - was reported for actions that produce morally relevant outcomes (Moretto et al., 2011). Importantly, increased intentional binding was found in PD patients in on vs. off medication, suggesting that dopamine might increase SoA (Moore et al., 2010). This project aims at investigating spontaneous deception in a social context in PD patients in order (i) to verify the presence of the “hyper-honesty” effect and (ii) to clarify the role of dopamine in modulating moral decision-making and SoA. For testing moral decision-making, we will employ the Temptation to Lie Card Game (Panasiti et al., 2011, 2014, 2016; Azevedo et al., 2017), a behavioral paradigm that proved effective for testing spontaneous deception (participants are free to decide whether to lie or tell the truth to the opponent player during a card game). Interestingly, this paradigm induces a moral conflict between the temptation to lie in order to get an economic reward and the desire to tell the truth, following the norms of moral conduct. For testing SoA, we will employ a novel behavioral paradigm in which multiple action features (movement congruency, goal attainment and timing of the action) are manipulated (Villa et al., 2018). Participants perform simple goal-directed action - pressing a button of a color of their choice (blue or yellow) by lifting or lowering the index - while viewing an avatar’s hand performing their same action or a different one in a mixed-reality scenario. The virtual action can be simultaneous or delayed, and participants provide synchrony judgments between their action and the observed one as a measure of SoA (Weiss et al, 2014). PD patients will perform both tasks twice (counterbalanced order): on- and off- dopaminergic medication. We expect that: (i) the frequency of self-gain lie decisions will be smaller in PD patients than in healthy control participants, (ii) the frequency of self-gain lie decisions will be lower in PD patients on-medication than in PD patients off-medication, and (iii) synchrony judgments will be higher (enhanced SoA) in PD patients on-medication with respect to PD patients off-medication. This project will help to clarify how dopaminergic treatment influences moral decision-making and SoA.
Does dopamine shape moral decision-making by inducing a change in sense of agency? An investigation of the “hyper-honesty” phenomenon in Parkinson’s Disease / Ponsi, Giorgia; Villa, Riccardo; Schepisi, Michael; Panasiti, MARIA SERENA. - (2018). (Intervento presentato al convegno São Paulo School of Advanced Science on Social and Affective Neuroscience, tenutosi a San Paolo; Brazil).