The researchers used a technique called transcranial magnetic stimulation (TMS, see picture). In short, it consists of placing magnets near the participant’s head and applying a magnetic field targeted at a specific brain region. The current generated by the magnetic field can pass through the skull and disrupts the targeted brain region. The whole thing is non-invasive and not painful.
Using this technique, the researchers disrupted a region called the right temporoparietal junction while participants were making moral judgments on scenarios like this one:
“Grace and her friend are taking a tour of a chemical plant. When Grace goes over to the coffee machine to pour some coffee, the friend asks for some sugar in hers.”
There are then four potential outcomes, which participants rated on a scale ranging from permissible to forbidden:
- Grace thinks the powder is sugar, and it is sugar, so everyone stays alive and happy.
- Grace thinks the powder is sugar, but it’s actually toxic, and the friend dies.
- Grace thinks the powder is toxic, but it’s just sugar, so Grace’s evil plan is thwarted and the friend lives.
- Grace thinks the powder is toxic, and it is toxic, and the friend dies.
Anyway, the researchers found that participants who underwent the procedure made similar moral judgments as control participants in all the situations but one: the instance where Grace thinks the powder is toxic but it’s not (#3 above). In this case, participants who had a part of their brain disrupted by TMS thought Grace’s actions were significantly more permissible than control participants. One might say their moral judgment was altered. In fact, almost every single news story that reported on this article suggested that the interpretation of these results meant that TMS to the right temporoparietal junction of the brain leads to altered moral judgments. So that must be where morality resides!
Interestingly, even the researchers do not claim this. In the article, they write: “TMS did not disrupt participant’s ability to make any moral judgement.” Remember, the TMS subjects rated 3 out of 4 outcomes the same as control participants. That means their moral compass is intact. It is also important to note that in the case where TMS participants thought Grace’s actions were more permissible than the control participants, this difference was only of about 15%. So what’s going on? Well, one can judge the morality of an action based on a number of criteria. The easiest criterion is outcome: did the friend live or die? Children under 6 (before the “age of reason”) mostly use this criterion to decide if actions are good or bad. But another criterion (among many others) is intent. Did Grace mean to poison her friend or not? In the situation 3, Grace meant to poison her friend, so if you were to judge morality on intent, it would be forbidden. But the friend lived, so if you judge morality on outcome, it would be permissible. What the authors suggest is that disrupting the right temporoparietal junction reduces how much one cares about intent. Which is different than “reduces one’s morality”.
Of course, like any good study, other interpretations cannot be ruled out. For example, TMS may interfere with other cognitive functions that have nothing to do with morality. Overall, the finding is interesting, but as always, more work needs to be done to get a better grasp of the inner workings of our morality.
Reference: Disruption of the right temporoparietal junction with transcanial magnetic stimulation reduces the role of beliefs in moral judgements. (2010) Young, L. et al. Proc Natl Acad Sci USA Mar 29 [Epub ahead of print].