Modulation of income redistribution decisions by anodal tDCS over the medial prefrontal cortex

One cause of the persistence of income inequality may be rooted in people's resistance to change the existing income distribution. Prior studies have shown that the medial prefrontal cortex (mPFC) may be associated with the decision making that influences income distribution. However, it is unclear whether the mPFC is involved in income redistribution tasks when third-party decision makers are unaffected by the outcome of the decision. In this study, we elucidate the neural mechanism underlying the tolerance of income inequality and the decision making that is related to income redistribution. By applying the transcranial direct current stimulation (tDCS) over the mPFC, we investigate whether the change in the activation of the mPFC can influence a subject's inclination to expropriate a rich person's endowment and transfer it to a poor person. The main finding is that the anodal stimulation significantly reduced the subject's inclination to redistribute wealth from the rich to the poor, and lowered the rate of accepting options for redistribution. However, the willingness of income redistribution did not change following the cathodal stimulation compared with the sham condition. The effect of the anodal stimulation was constant across three types of initial inequality. The stimulation effect is likely caused by the subject's enhanced loss aversion or desire to reinforce social hierarchies.