Far from making you smarter electrical stimulation of the brain's cells while solving challenging tasks can lead to mental overload warn researchers. The researchers wanted to test whether a treatment that sends a very weak electrical current through the skull to the outer layers of the brain so-called transcranial direct current stimulation (tDCS) can actually make us smarter. The tasks for the participants were divided into three levels -- simple medium and difficult. The researchers found no effect of stimulation when participants performed the simple and medium tasks yet they found a large negative effect on the most difficult tasks.
