WHEN making moral judgements, we rely on our ability to make inferences about the beliefs and intentions of others. With this so-called “theory of mind”, we can meaningfully interpret their behaviour, and decide whether it is right or wrong. The legal system also places great emphasis on one’s intentions: a “guilty act” only produces criminal liability when it is proven to have been performed in combination with a “guilty mind”, and this, too, depends on the ability to make reasoned moral judgements.

MIT researchers now show that this moral compass can be very easily skewed. In a new study published in the Proceedings of the National Academy of Sciences, they report that magnetic pulses which disrupt activity in a specific region of the brain’s right hemisphere can interfere with the ability to make certain types of moral judgements, so that hypothetical situations involving attempted harm are perceived to be less morally forbidden and more permissable.

Liane Lee Young of MIT’s Department of Brain and Cognitive Science and her colleagues asked participants to make moral judgements about different variations of a number of scenarios. One of these involves Grace and her friend having a cup of coffee during a tour of a chemical plant. In one version of it, she puts what she rightly believes to be sugar into her friend’s drink; in another, she puts what she believes to be poison, but what is actually sugar, into the drink; in the third variation, Grace puts poison into the cup, thinking it is sugar, and her friend dies; and in the final variation, she knowingly puts poison into the drink.

These scenarios differ in the beliefs underlying Grace’s actions and in their outcome. Most of us would agree that she acts “wrongly” by poisoning her friend in the fourth variation of the scenario. She was also wrong in the second, because although the outcome was neutral, she attempted to cause harm to her friend. On the other hand, most would agree that she was not wrong in the unfortunate scenario in which she unwittingly poisoned her friend. Although her act was guilty, her mind was not – it was not her intention to kill.

The researchers used an experimental technique called transcranial magnetic stimulation (TMS) to disrupt activity in the right temporoparietal junction (RTPJ), a region of the brain located just behind the ear which has previously been implicated in understanding the behaviour of others. In the “offline” condition, the participants received low frequency (1 Hz) magnetic pulses to the RTPJ or to a nearby control region for 25 minutes before reading the moral scenarios and making judgements about them. In the “online” condition, higher frequency bursts lasting half a second were applied while the participants read and judged the scenarios.

In both experiments, TMS applied to the RTPJ but not to the control brain region was found to impair the participants’ ability to make sound moral judgements in some cases but not in others. Judgements of scenarios involving intentional harm or no harm were unaffected, but the scenarios in which one character attempted unsuccessfully to harm another were judged to be more morally permissible. In other words, disrupting RTPJ activity significantly reduced the influence of belief on the participants’ judgements, so that they relied purely on the outcome of the scenarios, rather than on the intentions or motives of the character.

The authors conclude that the RTPJ is specifically required for attributing beliefs to others, or is part of a network containing a number of brain regions which are jointly necessary for belief attribution. The RTPJ appears to be strongly connected to other brain regions implicated in various aspects of social cognition, including attributing mental mental states to others. More evidence comes from another study by the same researchers published in the journal Neuron last week, which shows that moral judgements are also impaired in patients with damage to the ventromedial prefrontal cortex. Alternatively, perturbing RTPJ activity may have disturbed other cognitive functions, such as attention – it lies near a network known to be involved in attentional switching, but is anatomically distinct from it.  

Whether or not these findings extend to real world judgements remains to be seen. They may, however, have implications for autistics, who are thought to be incapable of inferring the mental states of others. Young and her colleagues hypothesize that autistic children and adults will exhibit deficits in the types of moral judgements used in this study, and are now testing this prediction. Interestingly, children up to the age of 6 years rely mainly on the outcomes of actions to make moral judgements, and tend to judge those who hurt somebody accidentally as being naughtier than someone who attempts to harm another but fails. This may be related to the late maturation of the RTPJ, and is another topic worthy of further investigation.

Young, L., et al. (2010). Disruption of the right temporoparietal junction with transcranial magnetic stimulation reduces the role of beliefs in moral judgments. Proc. Nat. Acad. Sci. DOI: 10.1073/pnas.0914826107.

Saxe, R. & Kanwisher, N. (2003). People thinking about thinking people: The role of the temporo-parietal junction in “theory of mind”. NeuroImage 19: 1835-1842. [PDF]

Baron-Cohen, S., et al (1985). Does the autistic child have a “theory of mind”? Cognition 21: 37-46. [PDF]


  1. #1 Nils Ross
    March 30, 2010

    As with the VMPC case, I have to ask whether the authors considered the possibility that it’s the ability to assess intent which is being affected, rather than the ability to make moral judgements about that intent?

  2. #2 Kameron Harris
    March 30, 2010

    “… but the scenarios in which one character attempted unsuccessfully to harm another were judged to be morally permissible.”

    I would say more morally permissible. The researchers see a statistically significant rise on their scale, but it doesn’t make it into the “permissible” region.

  3. #3 Mo
    March 31, 2010

    Kameron: Yes, that’s what I meant, as you can see from the second paragraph. Thanks.

  4. #4 Cat
    March 31, 2010

    Is your 7th paragraph deliberately full of errors as some sort of comedic reference to ‘attentional switching’?

    ” The authors conclude that the RTPJ is specifically required for attributing beliefs to others, or is part of a network containing a number of brain regions (surely you need the word ‘which’ here?) are jointly necessary for belief attribution.”

    ” Social cogntition? ” Is ‘cogntition’ a real word?

    And finally – “…which shows that moral judgements are also impaired patients with damage to the ventromedial prefrontal cortex.” Moral judgements are impaired patients? Are they really? What on earth are you trying to say here?

    Other than that I rather enjoyed your article, thank you.

  5. #5 Mo
    March 31, 2010

    No, Cat, they weren’t deliberate, so thanks for pointing them out.

  6. #6 Briana
    April 1, 2010

    Thanks for posting this (man I hope you know Cat personally because they seem to like ripping on you). This is an interesting topic… I wonder if there is any way magnetic pulses could naturally disrupt the brain in those areas due to some type of modern technology?

  7. #7 Mo
    April 2, 2010

    TMS is used to direct magnetic pulses very precisely at specified regions of the brain, so it’s unlikely that fields generated by devices could have such a specific effect. Having said that, some researchers argue that magnetic fields can induce paranormal phenomena by their effect on the brain, but the jury’s still out on that.

    I don’t know Cat, but I’m sure she’s lovely in person. If she wants to proof-read every post I write and point out typos etc., that’s fine with me.

  8. #8 Ruth Ferez
    April 12, 2010

    The brain is not the whole human being, the will is.

  9. #9 Anne
    April 13, 2010

    Great post.

    “Whether or not these findings extend to real world judgements remains to be seen.”

    Can you elaborate on what you meant by this? I am trying to figure out what implications these types of findings have for some of our criminal law concepts. I can see how these findings help elucidate the processes involved in belief attribution, but that’s about it. Perhaps I am being short-sighted?

  10. #10 Mo
    April 13, 2010

    Thanks, Anne. The moral scenarios were hypothetical, and we might act differently if faced with a similar but real situation. Experimental conditions are necessarily highly contrived and limited, and we shouldn’t assume that what happens under those conditions will also happen in the real world, where there are many more factors at play.

  11. #11 Houdini NFO
    April 22, 2010

    Interesting article in two ways: First, it confirms that the brain was designed with moral compass. Note that moral decisions were not improved by these magnetic pulses, but interfered with. Second, the location of this moral judgment center was behind the ears. Headphones and cell phone devices are placed next to our ears. Is technology affecting our moral compass as a society? Interesting question to study.

  12. #12 RV
    April 24, 2010

    Houdini NFO, how did you determine that the brain was designed with a moral compass?

  13. #13 MikeAlx
    April 27, 2010

    “children up to the age of 6 years rely mainly on the outcomes of actions to make moral judgements … This may be related to the late maturation of the RTPJ, and is another topic worthy of further investigation.”

    Interesting. Whilst many studies suggest a lack of theory of mind in the first three of four years, I believe there is now evidence that a basic T.O.M. is there almost from the start in non-autistic babies. Apparently, eye-motion studies of quite young babies watching a video of the Sally & Anne scenario (acted out) suggest that they seem to ‘expect’ correctly – not only do they look at the location where Sally believes the object to be, they oscillate between that and Sally’s face, as if anticipating her surprise.

  14. #14 Aaden
    June 26, 2010


    “Cognition” may be found in many elementary psychology books!

    “Patients” should have “in” in front!

    Hope this helps! Hang in there and keep asking questions! Asking the right qestions is the key to research innovation! Bad Freudian answers may be popular for many years and impede progress!