Transcranial stimulation of the frontal lobes increases propensity of mind-wandering without changing meta-awareness.

Mind-wandering is omnipresent in our lives. The benefits of mind-wandering are not yet clear, but given how much time we spend mind-wandering, this mental function is likely to be important. Accordingly, it is essential to understand the neural and cognitive mechanisms of mind-wandering. In a recent study by the leading author of the present paper it was demonstrated that by applying transcranial direct current stimulation (tDCS) of the frontal lobes, but not sham or occipital cortex stimulation, it was possible to increase propensity of mind-wandering. The goal of the present study has been to replicate these previous findings and to extend them by examining whether changes in mind-wandering as a result of stimulation are associated with a change of meta-awareness of the attentional focus. By using a larger sample size and by conducting the experiment in a different country and language, we fully replicated the key original findings by showing that stimulation of the prefrontal cortex increased the level of mind-wandering. We also show that stimulation had no major effect on the level of meta-awareness of the attentional focus. Taken together, our results indicate that mind-wandering - probably the most internal and self-related mental function - can be modulated externally, that at least in some cases mind-wandering might not be regulated by meta-awareness, and that the frontal lobes might play a causal role in mind-wandering.