Michael Buice on the dress

Read former LBM fellow Michael Buice’s explanation of the dress colour illusion.

Huffington Post: …In the case of the dress, one’s assumptions about lighting have a strong impact on the perceived color. In particular, your perception will be affected by whether your visual system sees the dress as being in bright light or in shadow. Comic book coloristNathan Fairbairn put together the following in order to illustrate these two different potential hypotheses about light and color in the picture.


So what happens if we try to remove contextual information? It so happens that these average colors are close to being inverses of one another. Inverting them gives us:


Inverting the colors in the original photo should approximately “swap” the two colors on the dress, as well as remove contextual information (or perhaps render it nonsensical). The color inverted dress looks like:


I see white-and-gold here, and I saw white-and-gold in the original. My wife is a die hard Black-and-bluer, and she sees the inverted dress as light-blue-and-gold. Notice that the image now has artifacts that look (to me anyway) like damage in an old photograph. This is a sample size of one, so I’m curious to know if this inversion changes the perceptions of any other black-and-bluers out there.

We know that training can alter the “light-from-above” prior, and it seems plausible that people’s differing perceptions of the photo are due to their different experience, and in particular their experience with light, shading, material, and overexposed photographs.

Our brains have to make guesses, but they don’t always make the same guesses, even though we live in the same world. One of the hardest inference problems our brains have to solve is figuring out how everyone else sees the world. Perhaps with some very hard work, I can be a Black-and-bluer, too.

Michael Buice is a scientist at the Allen Institute for Brain Science. His research interests are in identifying and understanding the mechanisms and principles that the nervous system uses to perform the inferences which allow us to perceive the world.


News as entertainment

This is an obvious observation but it struck me one day while watching the evening national news on multiple channels that the only thing that can differentiate between different programs cannot be news because true news is reported by everyone by definition. Half of all the news programs are identical and the other half covers random human interest stories. Given that the true news will have likely to have taken place earlier in the day, the actual news stories will not be novel. This clearly indicates that the national nightly news is doomed for extinction. Based on the commercials aired during the programs, the average demographic are senior citizens. Once they are gone, so will the nightly news, “and that’s the way it is“.

Is abstract thinking necessary?

Noted social scientist, Andrew Hacker, wrote a provocative opinion piece in the New York Times Sunday arguing that we relax mathematics requirements for higher education. Here are some excerpts from his piece:

New York Times: A TYPICAL American school day finds some six million high school students and two million college freshmen struggling with algebra. In both high school and college, all too many students are expected to fail. Why do we subject American students to this ordeal? I’ve found myself moving toward the strong view that we shouldn’t.

…There are many defenses of algebra and the virtue of learning it. Most of them sound reasonable on first hearing; many of them I once accepted. But the more I examine them, the clearer it seems that they are largely or wholly wrong — unsupported by research or evidence, or based on wishful logic. (I’m not talking about quantitative skills, critical for informed citizenship and personal finance, but a very different ballgame.)

…The toll mathematics takes begins early. To our nation’s shame, one in four ninth graders fail to finish high school. In South Carolina, 34 percent fell away in 2008-9, according to national data released last year; for Nevada, it was 45 percent. Most of the educators I’ve talked with cite algebra as the major academic reason.

The expected reaction from some of my colleagues was understandably negative. After all, we live in a world that is becoming more complex requiring more mathematical skills not less. Mathematics is as essential to one’s education as reading. In the past, I too would have whole heartedly agreed. However, over the past few years I have started think otherwise. Just to clarify, Hacker does not (nor I) believe that critical thinking is unimportant. He argues forcefully that all citizens should have a fundamental grounding in the concepts of arithmetic, statistics and quantitative reasoning. I have even posted before (see here)  that I thought mathematics should be part of the accepted canon of what an educated citizen should know and I’m not backing away from that belief. Hacker thinks we should be taught a “citizen’s statistics” course. My suggested course was:  “Science and mathematics survival tools for the modern world.”  The question is whether or not we should expect all students to master the abstract reasoning skills necessary for algebra.

I’ll probably catch a lot of flack for saying this but from my professional and personal experience, I believe that there is a significant fraction of the population that is either unable or unwilling to think abstractly.  I also don’t think we can separate lack of desire from lack of ability. The willingness to learn something may be just as “innate” as the ability to do something. I think everyone can agree that on the abstract thinking scale almost everyone can learn to add and subtract but only a select few can understand cohomology theory.  In our current system, we put high school algebra as the minimum threshold, but is this a reasonable place to draw the line? What we need to know  is the distribution of people’s maximum capacity for abstract thinking. The current model requires that  the distribution be  almost zero left of algebra with a fat tail on the right. But what if the actual distribution is broad with a peak somewhere near calculus?  In this case, there would be a large fraction of the population to the left of algebra. This is pure speculation but there could even be a neurophysiological basis to abstract thinking in terms of the fraction of neural connections within higher cortical areas versus connections between cortical and sensory areas. There could be a trade-off between abstract thinking and sensory processing. This need not even be purely genetic. As I posted before, not all the neural connections can be set by the genome so most are either random or arise through plasticity.

To me, the most important issue that Hacker brings up is not whether or not we should make everyone learn algebra but what should we do about the people who don’t and as a result are denied the opportunity to attend college and secure a financially stable life. Should we devote our resources to try to teach it to them better or should we develop alternative ways for these people to be productive in our society? I really think we should re-evaluate the goal that everyone goes to college. In fact, given the exorbitant cost and the rise of online education, the trend away from traditional college may have already begun. We should put more emphasis on apprenticeship programs and community colleges. Given the rapid rate of change in the job market, education and training should be thought of as a continual process instead of the current model of four years and out. I do believe that a functional democracy requires an educated citizenry. However, college attendance has been steadily increasing the past few decades but one would be hard pressed to argue that democracy has concomitantly improved. A new model may be in order.

The rise and fall of Jonah Lehrer

Jonah Lehrer , staff writer for the New Yorker and a best selling science author, resigned in disgrace today.  He admitted to fabricating quotes from Bob Dylan in his most recent book:

New York Times: An article in Tablet magazine revealed that in his best-selling book, “Imagine: How Creativity Works,” Mr. Lehrer had fabricated quotes from Bob Dylan, one of the most closely studied musicians alive. Only last month, Mr. Lehrer had publicly apologized for taking some of his previous work from The Wall Street Journal, Wired and other publications and recycling it in blog posts for The New Yorker, acts of recycling that his editor called “a mistake.”

…Mr. Lehrer might have kept his job at The New Yorker if not for the Tablet article, by Michael C. Moynihan, a journalist who is something of an authority on Mr. Dylan.

Reading “Imagine,” Mr. Moynihan was stopped by a quote cited by Mr. Lehrer in the first chapter. “It’s a hard thing to describe,” Mr. Dylan said. “It’s just this sense that you got something to say.”

Lehrer was a regular on Radiolab and he seemed to always really know his science. I have linked to his articles in the past (see here). His publisher is withdrawing his book and giving refunds to anyone returning it. I haven’t read the book, but from the excerpts and his interviews on it, I think the science is probably accurate. I don’t really know what he was thinking but my guess was that he was just trying to spice up the book and imagined a quote that Dylan might say. The fabricated quote above is pretty innocuous. He probably didn’t think anyone would notice. Maybe he felt pressure to write a best seller. Maybe he was overconfident. In any case, he definitely shouldn’t have done it. It is unfortunate because he was a gifted writer and boon to neuroscience and science in general.

The calorie debate

The day after I appeared on the radio show The Takeaway, Scientific American editor Michael Moyer came on to criticize me.  I welcome the debate and my response is below.

Here is a link to The Takeaway’s series on obesity, which has his audio file.  Moyer also writes in his blog:

Unfortunately Chow’s outsider’s perspective on the obesity crisis isn’t really an outsider’s perspective at all: it is the physicist’s perspective. Physicists have a long history of marching into other sciences with grand plans of stripping complex phenomena down to the essentials with the hope of uncovering simple fundamental laws. Occasionally this works. More often, they tend to overlook the very biochemistry at the heart of the process in question.

Chow’s conclusion is not just obvious—it’s a tautology. Because for Chow, a calorie is just a unit of energy. Eat more calories than you burn, and the energy must go somewhere. That somewhere is fat cells. The conclusion is built into the assumptions.

But perhaps a calorie is not just a calorie. Perhaps, as some prominent researchers argue, the body processes calories from sugar in a fundamentally unique and harmful way. According to this hypothesis, we’re not getting fat because we’re eating more. We’re getting fat because of what we’re eating more of. The biochemistry that explains why this would happen is complex—certainly difficult to include in a computer model—but that doesn’t make it wrong.

Ultimately experiments will decide if this hypothesis is true, or if it is not true, or if it is true but just one part of a nuanced understanding of obesity that includes biochemistry, microbiology, neurobiology, politics, economics and much more. The obesity crisis isn’t rocket science. It’s complicated.

Moyer’s criticism of me is ironic in two ways. The first is with regards to his claim that biology is not like physics. I fully agree and have posted on this very topic here. Additionally, while I have been frustrated in the past trying to get biologists to pay attention to my work, this is the one area where I am not a complete outsider and have access to and input from some of the very best clinicians, experimentalists, and public health scientists in the field.

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On the radio

I was a guest on two radio shows this morning.  At 7:45 this morning I was on The Takeaway, a nationally syndicated show on NPR (audio file available on website) and then at 10:30 I was on the Kathleen Dunn Show on Wisconsin Public Radio (audio file available here.  I am on halfway into the show). You can hear clearly that I’m not anywhere near as eloquent as Arif and Sebastian.

New York Times Interview

My conversation with Claudia Dreifus of the New Times can be found here.  I have to commend Claudia for putting in a great deal of effort on this piece. I never realized that they were so much work.  The published interview is a very condensed version of our many conversations.  Claudia did her very best to make sure everything was accurate but some nuance had to be sacrificed for space.  For example, I was engaged but not yet married when I moved to NIH.  Also, I want to point out that I did know that a calorie was a unit of energy but I had no idea that the food Calorie is really a kilocalorie nor how many Calories are contained in common food items.

One of the things that got cut from the story was that I heard about the job at NIDDK from John Rinzel.  The Laboratory of Biological Modeling that I’m now part of, used to be called the Mathematical Research Branch and John was its chief for twenty years. Wilfrid Rall was the chief before John. A brief history of the lab can be found here. One could argue that this was where computational neuroscience was established. Bard Ermentrout is among the many computational neuroscientists that passed through the lab. The branch actually predates the NIDDK and was put there for administrative reasons even though it focused on neuroscience.  However, near the end of John’s tenure as chief, the institute had less enthusiasm for the lab and resources were reduced.  John ended up leaving for NYU. Marvin Gershengorn came in as the new scientific director in the early 2000’s and he wanted to rebuild the lab. I have no doubt that I got the job because of the input Marvin received from John. Although Marvin was interested in obesity, he didn’t compel me to work on the topic.  He was very good about giving me and the lab freedom to work on anything interesting. Right now there are four PIs in the lab – Artie Sherman, Kevin Hall, Vipul Periwal and myself, and we work on a variety of biological topics although mostly with some connection to diabetes and metabolism. One thing that worried me about the piece, aside from a backlash from the food industry, was that it would pigeonhole me as an obesity researcher. I’m still very much interested in many topics including neuroscience, genetics and gene induction.

The last thing that doesn’t really make it through is that our argument for excess food causing the obesity epidemic is not just based on correlations between the increase in food supply and average body weight.  What we did was to take the actual USDA reported food availability per person, feed it to our calibrated model and showed that it more than explained the weight increase.  It may be that other factors liked decreases in physical activity are involved but they are not necessary to explain the obesity epidemic.  Those that doubt it was caused by excess food must show that all of it was thrown away.  We are already arguing that most of it was wasted.  Finally, I don’t really know how to stem the obesity epidemic.  I’m not sure that making food more expensive through taxation is the correct solution since it would cause hardship for low-income people.  I do think that curtailing food marketing to children would help but I’m not hopeful that it would ever happen.


Correction: Jun 7, 2012.  Will Rall was a member of the MRB but was never the chief.

Friends on Quirks and Quarks

Two of my old colleagues were interviewed on the CBC radio science show Quirks and Quarks recently.  This is the show I used to listen to in my youth in Canada. In March, astrophysicist Arif Babul, a classmate at the University of Toronto, talked about recent work he had done on abnormal clumping of dark matter in a collision site between clusters of galaxies. Here is the link.  Neuroscientist  Sebastian Seung, whom I’ve known since graduate school, talked about his recent book Connectome. Link here.  I was impressed by how well both were able to explain their work in clear and simple terms.  Their use of metaphors was particularly good.   I think these are two very good examples of how to talk about science to the general public.

New paper in The Lancet

The Lancet has just published a series of articles on obesity.  They can be found here.  I am an author on the third paper, which covers the work Kevin Hall and I have been working on for the past seven years.  There was a press conference in London yesterday that Kevin attended and there is a symposium today.  The announcement has since been picked up in the popular press.  Here are some samples:  Science Daily, Mirror, The Australian, and The Chart at CNN.



Coffee and your health

A recently published paper in the Journal of the National Cancer Institute reports that heavy coffee consumption can reduce the risk of prostate cancer.  This story made the rounds in the popular press as would be expected.  The paper is based on a longitudinal study of 47,911 health professionals.  What they found was that men who consumed more than six cups of coffee per day lowered their risk of developing prostate cancer by 18%.  While this sounds impressive, one must weigh this with the fact that the probability of getting prostate cancer was around 10% over the 20 years of the study.  So this means that six cups of coffee per day or more lowered the risk from  10% to 8%.  A reduction yes, but probably not enough to start drinking massive amounts of coffee for this purpose alone.  Stated in another way, the risk was reduced from  529 cancers per 100 000 person-years to 425 cancers.  Now, the study also found that the reduction in risk for severe prostate cancer was around fifty percent.  However, the risk of getting lethal prostate cancer is also lower so the risk drops from 79 cancers per 100 000 person-years to 34.

Now the problem with these epidemiological studies is that there are so many confounders, and although the authors were extremely careful in trying to account for them,  they are still dealing with very uncertain data.  Previous studies on the effects of coffee showed no effects on prostate cancer risk.  There is also the problem of multiple comparisons.  I’m sure the authors looked at risks for all sorts of diseases and this one turned out to be statistically significant.  As I posted before (see here and here), many if not most high-profile clinical results turn out to be wrong and for good systematic reasons.  Now, it is biologically plausible that coffee could have some effect in reducing cancer.  It contains lots of bioactive molecules and antioxidants and we should test these directly.  My take is that until there is a solid biophysical explanation for a clinical effect, the jury is always out.

Talk and SIAM news story

I gave a talk on obesity yesterday at Montclair State University.  The talk was mostly the same as the plenary talk I gave at the SIAM Annual and Life Sciences meeting in 2010, which I summarized here.  Science and math writer Barry Cipra also wrote a piece about the talk in SIAM News.   I find it amusing that he called me a mathematical obesity expert.   I presented the “push hypothesis” for the obesity epidemic in more detail here.

The push hypothesis for obesity

My blog post on the summary of my SIAM talk on obesity was picked up by Reddit.com.  There is also a story by mathematics writer Barry Cipra in SIAM news (not yet available online).  I thought I would explicitly clarify the “push” hypothesis here and reiterate that this is my opinion and not NIH policy.  What we had done previously was to derive a model of human metabolism that gives a prediction of how much you would weigh given how much you eat.  The model is fully dynamic and can capture how much you gain or lose weight depending on changes in diet or physical activity.  The parameters in the model have been calibrated with physiological measurements and validated in several independent studies of people undergoing weight change due to diet changes.

We then applied this model to the US population.  We used data from the National Health and Nutrition Examination Survey, which has kept track of the body weights of a representative sample of the US population for the past several decades and food availability data from the USDA.  Since the 1970’s, the average US body weight has increased linearly.  The US food availability per person has also increased linearly.  However, when we used the food availability data in the model, it predicted that the weight gain would grow linearly at a faster rate.  The USDA has used surveys and other investigative techniques to try to account for how much food is wasted.  If we calibrate the wastage to 1970 then we predict that the difference between the amount consumed and the amount available progressively increased from 1970 to 2005.  We interpreted this gap to be a progressive increase of food waste.  An alternative hypothesis would be that everyone burned more energy than the model predicted.

This also makes a prediction for the cause of the obesity epidemic although we didn’t make this the main point of the paper.  In order to gain weight, you have to eat more calories than you burn.  There are three possibilities for how this could happen: 1)  We could decrease energy expenditure by reducing physical activity and thus increase weight even if we ate the same amount of food as before,  2) There could be a pull effect where we became hungrier and start to eat more food, and 3)  There could be a push effect where we eat more food than we would have previously because of increased availability.  Now the data rules out hypothesis 1) since we assumed that physical activity stayed constant and still showed an increasing gap between energy intake and energy expenditure.  If anything, we may be exercising more than expected.  Hypothesis 2) would predict that the gap between intake and expenditure should fall and waste should decrease as we utilize more of the available food.  This then leaves us with hypothesis 3) where we are being supplied more food than we need to maintain our body weight and while we are eating some of this excess food, we are wasting more and more of it as well.

The final question, which is outside my realm of expertise, is why food supply increased. The simple answer is that food policy changed dramatically in the 1970’s. Earl Butz was appointed to be the US Secretary of Agriculture in 1971.  At that time food prices were quite high so he decided to change farm policy and vastly increase the production of corn and soybeans.  As a result, the supply of food increased dramatically and the price of food began to drop.   The story of Butz and the consequences of his policy shift is documented in the film King Corn.

More news stories on food waste