Brain Stimulation Can Change How You Punish Someone

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Justine Alford

Guest Author

2437 Brain Stimulation Can Change How You Punish Someone

The home of an elderly, widowed lady living in your neighborhood gets broken into at night by a man holding a knife. He steals her jewelry, raids her purse but leaves her unharmed. How should this man be punished? Does this decision change after you hear that he has a child with leukemia and couldn’t afford the medical bills, and so did this out of desperation?

Both of these moral decisions – determining blameworthiness and dishing out fair punishment – are the foundations of the enforcement of social norms, the behaviors society has deemed acceptable. But how do we make such judgments? According to new research, assessments of guilt and punishment actually take place in distinct areas of the brain. And though they’re connected, amazingly scientists have found they can experimentally alter one while leaving the other undisturbed.


The study’s focus was a brain region called the dorsolateral prefrontal cortex (DPFC), which has repeatedly been implicated in norm-enforcement and judgment based on norms. We know that this area is involved in the integration of information from other parts of the brain, and that this basic function likely underlies more complex behaviors and tasks, such as decision making. But how it contributes to our decisions regarding someone’s guilt and the price they should pay for an action has been hazy.

To find out more, researchers from Harvard and Vanderbilt universities rounded up 66 volunteers, male and female, and presented them with a series of hypothetical situations in which a crime had been committed, which ranged in severity from theft to murder. The likelihood that the prime suspect had done the deed also varied in the different scenarios, and some involved certain extenuating circumstances.

Participants then had to decide whether the accused was guilty, and how they should pay for their crime. At the same time, half the participants had the activity in their DPFC’s messed with using a "brain-buzzing" technique called repetitive transcranial magnetic stimulation (rTMS), whereas the others were given fake stimulation, although they didn’t know that. The results, published in Neuron, are fascinating.

As expected, the degree of harm caused and culpability were big predictors of the punishment they dished out. But what as interesting was that members in the group receiving the real rTMS were more lenient than those in the placebo group, especially concerning the less severe crimes, despite the fact that ratings of blameworthiness were seemingly unaffected.


By scanning their brains during the task, they found that the DPFC lit up during punishment decisions, but less so while determining blameworthiness. Additionally, analyses indicated that the reduced punishments observed in those receiving rTMS were likely due to an interference with the integration of signals coming from areas concerned with harm and culpability assessment.

According to the researchers, this suggests the presence of a neural dissociation between judgments of blameworthiness and decisions regarding punishment. Furthermore, determining appropriate punishment requires striking a balance between information regarding harm and culpability. 

Looking forward, lead researcher René Marois tells IFLScience it would be interesting to see how this decision making system is affected when the level of intent is varied. "It's not like the intent to commit a crime is all or none," says Marois. "Someone can do it purposefully, knowingly, recklessly, or negligibly. Or the act could have happened blamelessly.

"We're interested in not only varying the amount of harm, but also understanding the different degrees of mental state, because we know that also influences decision making."


Marois also explains that while we know there are individual differences in terms of how much someone will punish for a given crime, at the moment it is unclear why this is, but it's something his team is exploring.


  • tag
  • decision-making,

  • social norms,

  • morals,

  • blame,

  • punishment,

  • guilt