Anodal transcranial direct current stimulation over the right dorsolateral prefrontal cortex: Less risk taking or more reflective? A tDCS study based on a Bayesian-updating task

To identify the causal role of the DLPFC in decision making, we used transcranial direct current stimulation (tDCS) to investigate the contribution of DLPFC to performance in an incentivized decision task where optimal decisions require Bayesian updating of beliefs. In this task, an impulsive reinforcement-based heuristic can either conflict or be aligned with Bayesian updating. Previous research showed that in case of conflict individuals rely on the faulty heuristic, hence committing many decision errors. Based on the involvement of the DLPFC in inhibitory control we hypothesized that tDCS of the DLPFC would influence individual’s use of the reinforcement heuristic in case of conflict. 364 participants (158 in the original study; 206 in the replication study) received the anodal or cathodal tDCS stimulation to the right, left DLPFC or sham. While we observed improved decision making in first-draw decisions following anodal stimulation to the right DLPFC, our study did not find evidence indicating that tDCS stimulation over the DLPFC affected inhibition of reinforcement.