From dress codes to anti-incest laws, all human societies have social norms that specify how people should behave in various situations. Scientists have now shown that a zap of electricity to the brain can influence whether or not people choose to comply with these standards.
“The complexity of human interactions is so great, so independent, that our society would not function without standards,” said researcher Christian Ruff, professor of economics at the University of Zurich, Switzerland. “Even though humans know very much follow standards well, we are always tempted to break them. We need threats of punishment to be followed up properly, âRuff told LiveScience.
A previous study using functional magnetic resonance imaging showed that the right lateral prefrontal cortex (rLPFC) is activated when people follow social norms to avoid being punished. Ruff and his colleagues wondered if boosting this area could make people more or less susceptible to the threat of punishment. [The 10 Most Destructive Human Behaviors]
The researchers recruited Swiss students, who interacted with each other via a computer game with real monetary consequences.
During the experiment, the researchers applied small electric shocks called transcranial direct current stimulation to the rLPFC region of some of the participants’ brains. By varying the direction of the electric current, researchers could increase or decrease brain activity in this region. Some participants did not receive brain zaps and therefore served as a control group.
The students were matched and one student was given a sum of money, which she could choose how to share with another student. If the recipient felt the split was unfair, she could âpunishâ the student donor by withdrawing some of the donor’s money and investing it.
Students who started with money voluntarily chose to give only 10-20% on average. When the recipient punished them by withdrawing the remaining funds, the student donors paid 40-50% in subsequent rounds, which is closer to the standard of fairness in Western cultures of a 50-50 split, a Ruff said.
Brain stimulation had very different effects depending on whether students voluntarily followed the standard as opposed to when threatened with punishment.
When the threat of punishment was present, brain stimulation caused students to give more money, while shrinking brain stimulation caused them to give less money. In contrast, when the donation was voluntary, increasing and decreasing brain stimulation had the opposite effect, forcing students to donate less or more money, respectively.
Ruff and his colleagues also asked students to play gambling with computers rather than with other students. In this case, the stimulation of rLPFC had much weaker effects.
The results, detailed today (October 3) in the journal Science, suggest that rLPFC does not simply function as a switch that forces people to conform to social norms. Rather, this area of ââthe brain uses the social context to determine whether or not to conform to standards.
âHere, brain stimulation in the same region has opposite effects on cooperative behavior that depend entirely on context,â said neuroscientist Joshua Buckholtz of Harvard University, who was not involved in the study. Buckholtz suggested that the context of having a threat of punishment or not could change the connectivity between rLPFC and other areas of the brain.
The idea that the brain could be manipulated to make people more conformable to social norms has far-reaching implications for the legal system. âIf we know about this mechanism, we could think of ways to influence it to help people who are struggling to follow the standards,â Ruff said. But it’s not as simple as just zapping a criminal’s brain into complying with the law.
“There is a big difference between an acute change in the lab and a long-term change in the way people represent and process social norms in nature,” Buckholtz said.