Limitations and future directions
Our study has some limitations. Firstly, it is still unclear whether the effects we observed in the current experiment can be extended to situations in which consequences are not merely monetary and much more serious. Intentions in our study are limited to the financial fairness dimension. Our experimental design does not speak to more evil motives, such as to harm, to sabotage, and to kill. Secondly, it is possible that other brain regions apart from the rTPJ may also be modulated indirectly by tDCS. Future studies may directly measure the neural activity at the whole brain level after tDCS. Lastly, our findings need to be treated with caution and wait for further replications. Future studies may further investigate the dose effect of tDCS and the effects of other tDCS protocol parameters.