It's hard to imagine anyone, no matter how brilliant, who doesn't yearn to be even smarter. Thanks to recent advances in neural science, that wish may come true. Researchers are finding ways to rev up the human brain like never before. There would be just one question: Do we really want to inhabit that world?

It may be too late to ask. Modern society has already embraced the basic idea of fine-tuning our intellects via artificial procedures—what might be termed “cosmetic” neurology. Schoolchildren take Adderall, Concerta and other attention-focusing medications. Parents and teachers rely on antidepressants and antianxiety drugs. And self-help books offer the latest advances in neuroscience to help ordinary people think faster and sharper.

Add to those advances another cognitive-enhancement method: transcranial direct-current stimulation (tDCS). With this technique, electrodes applied to the scalp deliver minuscule amperages of current to the brain. This trickle of electricity seems to cause incremental adjustments in the electrical potentials of membranes in the neurons closest to the electrodes, increasing or decreasing their likelihood of firing. And that, in turn, induces measurable changes in memory, language, mood, motor function, attention and other cognitive domains.

Investigators still aren't sure whether tDCS can cause long-term neural changes. Although most tests show only transient effects, there is limited evidence that repeated applications might have more persistent results. The procedure is not approved by the U.S. Food and Drug Administration, and the consensus among experts is that it should be performed only under qualified supervision. Nevertheless, if used properly, it is safe, portable, easy to implement and inexpensive.

The idea is so straightforward that some do-it-yourselfers have built their own devices for home use, ignoring cautionary disclaimers. Even though such a freewheeling approach won't appeal to everyone, electronic brain stimulation has a chance of catching on. In a recent online survey, 87 percent of respondents told us they would undergo tDCS if it could enhance their performance at school or work.

Should we welcome this opportunity to become smarter, faster, more attentive versions of ourselves? Although a few neuroscientists have unreservedly endorsed general use of this hot-wired thinking cap, others (including us) are not so sure. Safety is a paramount concern with any biomedical device. And what about distributive justice? If tDCS becomes widely available, will the wealthy use it to compound their privileged status?

Other issues are more perplexing. Brain-manipulating technologies such as tDCS might conceivably allow users to rewire the neural machinery that underlies critical aspects of an individual's cognitive experience and selfdom. Extending this thought to its logical conclusion, one could ask whether users might ultimately find ways to transform themselves. Beyond that, would it be acceptable to impose such changes on others—students, say, or workers, or soldiers—for the sake of strengthening certain skills? And what of society itself? If individuals build moral fiber by struggling against their own limitations, would something vital be lost if every challenging cognitive task or emotionally difficult moment could be eased with the press of a button?

We doubt that these extremes will come to pass. Still, they are worth examining when contemplating decisions that could have inadvertent outcomes. Any brain-enhancing techniques will have to be evaluated case by case, as society comes to a fuller understanding of their trade-offs. If such procedures become widely available, scientists and practitioners will bear the responsibility of teaching the public to use the technology safely and appropriately. Until then, we can only say that tDCS and similar tools are cause for excitement—and for caution.