People’s moral judgment can be altered by disrupting part of the brain, a study published Monday in the Proceedings of the National Academy of Sciences shows.
Researchers at the Massachusetts Institute of Technology (MIT) disrupted activity in the right temporo-parietal junction, or TPJ, which is above and behind the right ear and is usually highly active when we think about what we believe the outcome of a particular act will be.
The researchers disrupted the TPJ by inducing a current in the brain using a magnetic field applied to the scalp and got study participants to read a series of scenarios posing moral conundrums.
In one scenario, a person called Grace and her friend are taking a tour of a chemical plant when Grace stops at the coffee machine.
Grace’s friend asks her to get her a coffee with sugar.
A container by the coffee machine is marked ‘toxic’ but contains plain old sugar — but Grace doesn’t know that.
She believes the white powder in the container is toxic but puts it in her friend’s coffee anyway. Her friend is unharmed because the substance was sugar.
Participants in the study were asked to judge on a scale of one to seven, with one being “absolutely forbidden” and seven “absolutely permissible,” if they thought what Grace and other protagonists in other scenarios did was morally acceptable.
Two experiments were conducted: during one, participants were asked to judge the scenarios’ characters after having magnetic pulses sent to their TPJs for 25 minutes, and in the other they passed judgment while undergoing very short bursts of magnetic interference.
In both experiments, disrupting normal neural activity in the right TPJ switched off the part of people’s moral judgment mechanism that looks at the protagonists’ beliefs.
When the right TPJ was disrupted, participants were more likely to judge as morally permissible failed attempts to harm another person than were control participants whose right TPJs were not tinkered with.
“When activity in the right TPJ is disrupted, participants’ moral judgments shift toward a ‘no harm, no foul’ mentality,” even though the participants should have given characters like Grace a mark in the forbidden range because they believed their actions would cause harm, the study says.