Transcranial Direct Current Stimulation Of The Medial Frontal Cortex Modulates Choice-Induced Preference Changes

Cognitive dissonance arises as a reaction to conflict appearing in choices between two equally attractive options. It leads to changes in the desirability of these options. The chosen option becomes more desirable whereas the rejected option is devalued. Despite cognitive dissonance being largely used by social psychologists to explain social conformity and preference re-evaluation, little is known about the neural mechanisms of such choice-induced preference changes. In this study, we modulated the activity of the posterior medial frontal cortex (pMFC), which has been found to be involved in cognitive dissonance in neuroimaging studies. We influenced the activity of the pMFC before individual choices using both cathodal and anodal transcranial Direct Current Stimulation (tDCS) during a revised version of Brehm's free-choice paradigm. Our results showed that cathodal tDCS over the pMFC significantly decreased the typical choice-induced preference change relative to a sham stimulation. On the contrary, no significant effect of anodal tDCS was observed. Our findings of the influence cathodal tDCS on preference re-evaluation highlight the central contribution of the pMFC in cognitive dissonance and provide evidence that pMFC plays a key role in the implementation of subsequent post-decision preference change.