Guy Kahane’s Posts

The Stuff Dreams Are Made Of

Studies of the content of dreams confirm what most of us already suspect: dreams are more likely to be nasty than pleasant, or as the researchers put it, “negative dream contents are more frequent than corresponding positive dream contents”. A recent study reports that threatening experiences are more frequent and intense in dreams than in real life. All this is in line with the entertaining (and not implausible) ‘threat simulation theory’ of dreams, according to which the evolutionary function of dreams is to simulate threats so that our ancestors could spend their nights rehearsing attacks by enemies and predators.

So dreams have a serious negative bias. All of this might have been extremely useful back then. But an unwelcome consequence is that we spend a large portion of our life in pointless misery. Clinical depression is often understood as a disposition to obsessively accentuate the negative. It seems all of us are clinically depressed during certain hours of the night. Think of a human life and how many hours of sleep it contains. Of these, many are spent dreaming. And most of these dreams are unpleasant in different ways. If we add all this up, dreaming makes our lives significantly worse, on balance. Shouldn’t we do something about this?

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Peering into the mind and ‘new threats to privacy’

In recent studies, neuroscientists have been able to use brain imaging to reliably predict inner states such as lying or intention. In a groundbreaking study published in a recent issue of Nature (and briefly summarised here, here and here), Kay and his colleagues used functional magnetic resonance imaging (fMRI) to make predictions about what subjects were seeing. Using a complex mathematical model based on decades of research into the human visual cortex, measured brain activity to estimate which grayscale natural image the subject was seeing at a given point in time. This goes beyond prior attempts at ‘brain reading’ in that the analysis did not merely use simple artificial stimuli or generic statistical signal-processing methods to identify neural patterns but employed data about the early stages of visual processing to develop a model that was then able to accurately predict which of a large number of novel and complex natural images was seen by the subject.

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Restoring Sensation to Amputees’ Lost Limbs

Scientists at the Rehabilitation Institute of Chicago and Northwestern University made two amputees ‘feel’ their lost arms by rerouting to their chest the key nerves that transfer sensations from hand to brain. After several months, stimulation to the area of the nerves would produce rich sensations experienced as if occurring in the missing limbs. Interestingly, the patients could still distinguish between sensory stimulation of chest nerves and that of the rerouted arm nerves.

For a summary, see Yahoo News

For the original paper, see PNAS paper

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Imaging the Political Brain

In an interesting study published in the Journal of Cognitive Neuroscience in 2006 but widely circulated earlier, Drew Westen and his colleagues at Emory University used fMRI to image the brains of committed Democrats and Republicans before the 2004 Presidential election. Although the subject matter was topical, the aim of the study was not to contribute to the political debate but to shed light on the neural processes involved in emotion-driven motivated reasoning. But an opinion piece published about a week ago in the New York Times goes quite a bit further. Authored by a group of neuroscientists, the piece reported the results of brain imaging scans of 20 registered voters who were showed still photos and video excerpt from speeches of the leading Democratic and Republican candidates for the upcoming presidential election. The piece included amusing remarks such as

Emotions about Hillary Clinton are mixed. Voters who rated Mrs. Clinton unfavorably on their questionnaire appeared not entirely comfortable with their assessment. When viewing images of her, these voters exhibited significant activity in the anterior cingulate cortex, an emotional center of the brain that is aroused when a person feels compelled to act in two different ways but must choose one. It looked as if they were battling unacknowledged impulses to like Mrs. Clinton.

Neuroscientists have now started playing political pundits and, as some might put it, are risking confusing solid science with something worryingly close to astrology. The confident, chatty interpretations given by the authors to activation in various areas of the brain in response to the image of a politician go well beyond anything backed by serious science. To be sure, there is plenty of evidence that the anterior cingulate cortex has a role to play in certain emotions, and in some forms of decision-making, but it’s a very big jump to conclude that the subjects in the study were ‘battling unacknowledged impulses’. It is a VERY big jump to suggest, on the basis of such responses from some of the twenty (presumably) Californian voters, that this is what American voters feel.


Such uses (or abuses) of science raise many ethical issues. Let me just draw attention to a few. The first of course has to do with the relation between science and the popular media. Should neuroscientists write such opinion pieces? It would be fat better if they didn’t. But whether we like it or not, we are likely to see more of such neuropunditry. Like many cultural-technological innovations, what is a curiosity today might be an obvious fact of life tomorrow.


The first thing to point out is that such an opinion piece, although written by scientists, is nothing like a peer-reviewed article in a major scientific journal. We are given interpretation but no data and little information about the methodology. We cannot say if the methodology is sound or rule out various forms of bias. The problem is, however, that such neuropunditry isn’t really compatible with the existing peer-review process. It needs to come out fairly quickly to be really relevant commentary on ongoing political events. The peer-review process is too cautious and slow. But perhaps a similar kind of scientific ‘quality control’ could be developed to serve a parallel role.


Another issue is that it not yet clear that using fMRI technology in this way can really teach us anything about the psychology of voters that we couldn’t learn using the traditional methods of questionnaires and polling. The public should be made aware of the limits to what brain imaging can tell us. Nevertheless, fMRI offers, at least in potential, a uniquely direct access to unconscious processes the subject may not even be aware of—as well as a way of spotting all too real responses some subjects do not acknowledge. Indeed it is possible that even some the loose empirical speculations in the New York Times piece do identify something real about the psychologies of many American voters. In any case brain imaging and our ability to interpret its findings is advancing fast—we will certainly know much more about the neuroscience of emotion or political judgment in four years—so it is also, finally, worth asking what good it would do to have such insight into the hidden psychology of voters. Unsurprisingly, the answer seems to be that very little. Perhaps brain imaging can reveal to us that some voters have mixed feelings about Senator Clinton, but it tells us little or nothing about their reasons for that, let alone whether these are good reasons. Brain imaging studies of emotional bias such as that mentioned above, could in principle be used to seek ways of increasing rationality in politics but, like what I called ‘neuropunditry’, are far more likely to be used in the service of psychological manipulation.





1. Drew Westen, Pavel S. Blagov, Keith Harenski, Clint Kilts and Stephan Hamann  Neural Bases of Motivated Reasoning: An fMRI Study of Emotional Constraints on Partisan Political Judgment in the 2004 U.S. Presidential Election   Journal of Cognitive Neuroscience. 2006;18:1947-1958


2. ‘This is Your Brain On Politics’ , New York Times, 11 November 2007