Scientists have found that they can make people selfish and egotistical by turning off a brain region at the flick of a switch
They set out to show that activation of the area of the brain known as the dorsolateral prefrontal cortex (DLPFC) triggers self-control.
The scientists used repetitive transcranial magnetic stimulation on subjects, in which a weak magnetic field was used to temporarily disable the DLPFC.
Then they took part in a bargaining game in which two individuals had to agree on the division of a given amount of money.
One person proposed an offer and the other could either accept or reject it — but rejection meant that neither got any money.
The researchers found that suppressing the right side of the DLPFC made the volunteers more likely to accept unfair offers instead of rejecting them in order to punish the "proposer" for not sharing more equally.
Subjects who had the right DLPFC turned off were far less able to keep their selfish impulses under control, though they still knew what was fair and what was not.
"Our study suggests that right, but not left, DLPFC is involved in overriding selfish impulses while it does not affect subjects' fairness judgements," said Prof Ernst Fehr, an economist.
The insight into the brain circuits that regulate selfish impulses is published today by Prof Fehr and the neuroscientist Prof Daria Knoch, of Zurich University, with Prof Alvaro Pascual-Leone, of Harvard.
Prof Knoch dismissed fears about the unethical use of the method, saying that the effect was of only short duration and required the permission of the person undergoing the stimulation.
Earlier studies using a brain scanner method had suggested that self-control depended on the DLPFC, which is among the last brain areas to mature.
The new research, published in the journal Science, points out that the same part of the brain is not fully developed in young people, which could account for their notoriously selfish behaviour.
Human society depends on fairness, co-operation, politeness, punctuality, and honesty — and on punishing those who violate these norms.
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