right Oateral Prefrontal Cortex. Source: Science magazine

Hopefully, most of us (some politicians notwithstanding) adhere to a set of norms of fairness that are the connective tissue of our society. These norms are not necessarily thesame for every society. Some “primitive” small tribes subsisting on gathering plants and the occasional kill will share everything not just with the immediate family but with the whole tribe. When suggested to them by researchers that they provide for themselves or their immediate family -it was literally beyond their comprehension. In larger tribes such  egalitarianism is not practical and the immediate family becomes paramount. But the common thread that runs through all cultures, societies, and the individuals which they comprise is a sense of fairness that is acceptable to their respective cohorts. Is it altruism, or is it fear of retribution?

Brain-scanning studies by several groups had suggested that the right lateral prefrontal cortex (rLPFC) is involved in following social norms and in the urge to punish violators, This brain area is located behind the right edge of your eye. But “involved” still doesn’t tell us what exactly is happening in this area: is it the cause of a fair behavior?,  is it ancillary, or even just correlates with fair behavior, while the main action takes place elsewhere in brain?

A fascinating paper has just been published in Science Online by a group at the University of Zurich in Switzerland, with accompanying commentary by Elizabeth Culotta, a science writer for the magazine. The researchers had 63 female undergraduates (to maximize uniformity of the sample) play a money game typical in behavioral economics research. The researchers crafted their game to expose the workings of a norm in which the participants were encouraged to share equally, or close to it.. In a baseline round, Player B has no way to sanction Player A for defying the norm; the latter therefore typically gives away only a little money. In the so-called punishment round, Player A faces a threat from Player B, who can expend her own funds to cause Player A’s money to vanish. People typically share much more, 40% to 50%, in this case.

But the researchers didn’t stop there. They applied transcranial direct current stimulation (tDCS) to the rLPFC, making neurons in that area more or less excitable, depending on the current applied to it. And the result? During the baseline round, participants with a positively charged electrode—which boosted rLPFC activity—selfishly kept even more money to themselves than when the current was off, thus violating the norm. But once they faced a risk of punishment, the norm was reinforced, and they shared even more than they had during the sham trial. The women playing under a negatively charged electrode, which decreased activity in this brain region, made opposite choices, giving away more money in the baseline round but changing their behavior much less when facing possible punishment.

So the rLPFC, the area that was associated with fair behavior isn’t really that liberal. It is more crafty than fair. When stimulated it actually promote self-serving, unfair behavior. It was the risk of punishment that restored return to social norms of fairness. So it seems that this area is involved in weighing the pros and cons of acting fairly, and acts accordingly. When no adverse consequences to selfish behavior are present -it “allows” bad behavior; when such behavior is likely to be punished  -it restores adherence to the social norm. In other words, it chooses whether to comply. What about the brain centers that are involved in understanding a norm? The experiment suggest that they deployed elsewhere in the brain.

Although manipulating their rLPFC apparently affected their decisions, the participants were unaware of this. Their conscious evaluations of the game, measured through questions such as how much anger Player B might feel at a certain response, remained the same as during sham stimulation. Which leads us to the conclusion that fair behavior, the glue of our sociality, is not driven solely by altruistic impulses, but by fear of punishment as well. And it is hard-wired in the brain. Food for thought when we considering a myriad of public policy issues.

But the implication of this research may be even more profound. Just consider the Manchurian Candidate. Who needs primitive methods such as brainwashing? a positive or negative transcranial direct current directed to the right brain area can alter our behavior, without us even being aware of it. This is not the stuff of science fiction anymore; it’s real, and it is here. On the other hand, wouldn’t it be nice if our representatives in DC got a dose of negatively charged DC to their heads to make them more fair, or at least fear punishment for behavior that does not conform with our social norms? One can only dream.






Dov Michaeli, MD, PhD
Dov Michaeli, MD, PhD loves to write about the brain and human behavior as well as translate complicated basic science concepts into entertainment for the rest of us. He was a professor at the University of California San Francisco before leaving to enter the world of biotech. He served as the Chief Medical Officer of biotech companies, including Aphton Corporation. He also founded and served as the CEO of Madah Medica, an early stage biotech company developing products to improve post-surgical pain control. He is now retired and enjoys working out, following the stock market, travelling the world, and, of course, writing for TDWI.


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