Brain and politics 2.0: Respuesta aclaratoria de Marco Iacoboni en referencia a su op-ed en el New York Times ("Your brain on politics" 2007)

Some time ago we published an op-ed in the New York Times (?Your brain on politics,? November 11, 2007). The op-ed generated many comments, in some cases these comments fit well Daniel Goleman?s expression ?amygdala hi-jack? (when emotions take over rational and fair thinking) because they contained contradictory statements that can?t possibly go together. For instance, a very short letter to the New York Times, signed by 17 cognitive neuroscientists, says in its penultimate paragraph that our op-ed does not provide ?sufficient detail? to ?evaluate the conclusions.? Amazingly, the last sentence of this short letter says that we ?draw unfounded conclusions? in our op-ed. These contradictory statements have been already noted by Adam Kolber in his Neuro-ethics blog.


Contradictory statements were also made in a Nature editorial that lamented the ?absurdity? of our interpretations and then concluded with ?And does anyone need a $3-million scanner to conclude that Hillary needs to work on her support from swing voters?? Did we say absurdities or make trivial statements? It can?t be simultaneously both.


I tend to respond to what is worth responding, and frankly those contradictions didn?t inspire a response. A recent article by Michael Shermer on SciAm.com - quoting extensively Russ Poldrack, one of the 17 scientists that signed the letter to the New York Times - made me change my mind. Shermer?s article associates our New York Times op-ed with the concept of brain modularity. (It also associates the op-ed with pseudoscience, phrenology, and even astrology, comments that while are not worth responding, are worth citing here to give you a sense of how our op-ed still stirs quite a bit of emotions.) It is amusing to see my name associated with brain modularity. I support the concept of modularity in the brain as Sam Harris and Richard Dawkins support religious beliefs or the Christian evangelic right supports stem cell research, abortion, and gay marriage. There is nothing in the New York Times op-ed ?This Is Your Brain on Politics,? that advocates modularity. It is quite surprising to see how Shermer embraces Poldrack?s gross distortions of the assumptions behind the New York Times op-ed. As a publisher of Skeptic, shouldn?t Shermer have a more skeptical attitude?


It is unlikely that there are module a la Fodor in the brain. Indeed, not even Fodor probably believes it anymore. However, there is a large peer-reviewed scientific literature that associates mental states with brain structures. It is possible to use such literature to interpret brain activity as ?probabilistic marker of mental states.? For instance, there are more than 1,000 peer-reviewed published papers that associate the amygdala with anxiety. There are also some papers that associate the amygdala with happiness. How many? Less than 100 (I did this survey about six months ago, this is why I am giving approximate numbers.) It is irrational to assume that activity in the amygdala can be associated with anxiety or happiness with equal probability.


Shermer?s article also quotes Poldrack?s criticism on the practice of ?reversing the causal inference,? which is the basis of interpreting brain activity as ?probabilistic marker of mental states.? Shermer (and the signatories of the letter to the New York Times) fail to say that ?reversing the causal inference? is a common practice in neuroimaging. The beautiful study on the neuroanatomy of belief recently published by Sam Harris and colleagues takes the activity in the insula while reading statements that subjects did not believe as suggesting that disbelief invokes disgust. There is nothing in Sam Harris? study that tells us that subjects were truly disgusted. A recent brain imaging study by John Cacioppo on social isolation interprets activity in the striatum as representing reward processing. There is nothing in Cacioppo?s design that can demonstrate that the activity in the striatum truly represents processing of reward. Ironically, Cacioppo also co-signed Poldrack-led letter to the Times quoted by Shermer. I could probably find examples of ?reversing the causal inference? for all the signatories of that letter. Indeed, I would argue that even Poldrack himself exploits some level of reverse inference in his own studies. In a recent paper led by Adam Aron (he also signed the letter to the New York Times) on response inhibition, Aron and colleagues interpret activity in pre-SMA (a frontal lobe area) as reflecting a ?conflict/detection resolution role.? While this interpretation is very reasonable, it would be much less reasonable if the brain activity was located in primary visual cortex. Aron and Poldrack would have not interpreted activity in primary visual cortex during a response inhibition paradigm as reflecting a ?conflict/detection resolution role? of the primary visual cortex. Anatomical location of brain activity matters, because there is not a single study that can reveal the absolute truth. Incidentally, this notion applies to all science, not just brain imaging. Science is about reproducibility of results. The results from individual experiments must always be compared to a larger corpus of data. A propos, as Francis Crick once said, ?Any theory that can account for all of the facts is wrong, because some of the facts are always wrong.? If we take this approach, we must also conclude that it is highly unlikely that more than 1,000 scientific papers are wrong (amygdala and anxiety), but it is definitely not inconceivable that less than 100 papers are wrong.


Our New York Times op-ed applied this rational probabilistic logic to brain responses in voters watching candidates. By doing so, it also provided a splendid example of how one can do civic education by using scientific constructs and rational thinking for issues that matter to people. Sadly, science has still a marginal role in our public discourse and this is in part due to an ?ivory tower? attitude of many scientists that are afraid of mixing the ?pure science? of the lab with real life issues. The by-product of this attitude is a society in which basic concepts that emerged from science - for instance, evolution - are challenged by adopting the irrational position that the evolutionary framework ?can?t explain all data.?


I would argue that all neuro-something disciplines (neuro-economics, neuro-ethics, neuro-politics and so on) should rely heavily on the very same assumptions we adopted in our op-ed. This is necessary, if one wants to combine the tools developed and the knowledge acquired by neuroscientists to address issues that are important to our society.


Marco Iacoboni, MD PhD
Author, Mirroring People


Director, Transcranial Magnetic Stimulation Lab
Ahmanson-Lovelace Brain Mapping Center
David Geffen School of Medicine at UCLA