Moral judgments can be manipulated using magnetic waves. How MIT scientists discovered a way to change people's sense of right and wrong

A person's sense of right and wrong may depend partly on how the brain interprets another person's intentions. In a surprising experiment, scientists at the Massachusetts Institute of Technology (MIT) found that applying magnetic pulses to a specific brain region could temporarily change how people judged morally questionable actions. Participants became more likely to consider harmful behaviour acceptable when the intended harm did not actually occur.

The findings, published in the journal Proceedings of the National Academy of Sciences (PNAS) in March 2010, offered evidence that moral judgments are linked to specific brain processes. Researchers disrupted activity in a region above and behind the right ear, and found that this affected the extent to which participants took into account another person's intentions when deciding whether an action was right or wrong.

How magnetic pulses altered moral judgments

MIT researchers used a non-invasive technique known as transcranial magnetic stimulation (TMS). It works by putting a magnetic field on the scalp, which induces weak electrical currents that briefly disrupt the normal activity of nearby brain cells.


The experiment looked at a part of the brain known as the right temporoparietal junction (RTPJ), which helps us understand what other people are thinking, believing and intending.

The research team was led by neuroscientist Rebecca Saxe and the study’s lead author was Liane Young. To test whether interfering with this region would impact moral decision-making, they ran two experiments with 20 participants.

In one experiment, volunteers had 25 minutes of magnetic stimulation and then read stories about morally questionable actions. In another, researchers applied magnetic pulses lasting 500 milliseconds while participants were making their judgments.

Participants rated the actions on a scale of one to seven, ranging from absolutely forbidden to absolutely permissible.

Why intentions mattered less after brain stimulation

One scenario involved a man who allowed his girlfriend to cross a bridge that he knew was unsafe. She managed to cross it without getting hurt.

Under normal circumstances, people would think of the man’s intention to cause potential harm, despite the result being harmless. But participants with disrupted RTPJ activity were more likely to judge his actions as morally acceptable because nobody got hurt.

In another case a girl made a tea for another girl with powder from a container marked toxic. The powder was actually sugar so the other girl was not hurt.

When the researchers disrupted activity in the targeted brain region, participants were more likely to judge the girl’s actions as acceptable, taking the outcome into greater consideration than what she thought she was doing.

Basically, participants were more likely to see attempts that failed to cause harm as morally permissible. It didn't turn their moral beliefs completely upside down but it did change how they weighed intentions against consequences.

What the experiment reveals about human brain

The results revealed the role of a psychological ability known as theory of mind. It refers to the capacity to understand that other people have their own thoughts, beliefs and intentions, which may differ from reality.

Researchers suggested that the RTPJ helps people use this information when judging another person's behaviour.

But morality isn't just the job of one brain area. People’s judgments are motivated by emotions, personal experience, desires and ideas about fairness and responsibility.

A 2014 study in Frontiers Neurosciences took an even deeper look at this complexity. The researchers studied the effects of TMS on two brain regions: the right dorsolateral prefrontal cortex (DLPFC) and the right TPJ. They found that damage to these areas affected different types of moral decisions . This shows that emotional responses and reasoning are both involved in moral judgments .

The 2010 experiment did not show that scientists could permanently change someone’s values or personality. Instead, it showed that a temporary disruption of one specific brain process could affect how people judged another person’s behavior.