Archive for February, 2007

Feb 28 2007

Plastic Brains

Published by under Neuroscience

Recently I was chatting with my sister-in-law, who is a psychiatric APRN, about how plastic the brain is when my 7-year-old daughter, who had been listening in, asked incredulously, “Our brains are made of plastic?” I had to explain to her that I didn’t mean that plastic, but rather that our brains can change and adapt with use.

It is a very fortunate property of vertebrate brains that they can “rewire” themselves to some degree based upon need and use – a property known as plasticity. The brain can remember and learn stuff, so it’s not surprising that it changes with use. That is the essence of learning. But plasticity is different than just memory. If refers to the rewiring of the structure of the brain for a new type of use, not just forming memories in established brain tissue.
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Feb 27 2007

Correlation and Causation Does Aspirin Cause High Blood Pressure?

Yesterday I wrote about the problem of using data mining to find chance correlations that are not “real.” I mentioned, but did not discuss further, the other problem with correlation data – the assumption of causation from correlation. By minor coincidence today many news outlets are reporting on a newly published study that correlates hypertension (high blood pressure) in men with use of aspirin, acetaminophen, and ibuprofen – common pain killers. But what does this correlation mean?

The assumption of causation from correlation is a common logical fallacy – A correlates with B therefore A causes B. A might cause B, but it is also possible that B causes A or that a third factor, C, causes both A and B. So how do we know what the real causal relationship is? The definitive way is to do a randomized controlled prospective study – which means randomly creating A and then observing to see if B follows. This type of protocol controls for B causing A or some other factor C causing both. But there are other ways of inferring causation, even to a high degree of confidence, without such a prospective study. First, you can consider mechanism and plausibility – does it make sense that A could cause B or B could cause A? Second you can look at multiple correlations that would be predicted from one causal relationship. For example, if A causes B then as A increases B should also increase, and if A goes away then B should diminish or disappear. You can also look at known (C) factors to see if they also correlate with A and B.
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Feb 26 2007

Data Mining – Adventures in Pattern Recognition

Correlations everywhere, now I must stop to think.

Science is often tricky business, requiring both detailed knowledge and sophisticated understanding. Pseudoscientists often earn the label of “pseudo” because they just don’t get the details right – often persistently in one direction with profound implications to their conclusions. To be a good scholar in any field, and in science in particular, it is a prerequisite to have at least a basic understanding of logic – of how to think. This includes knowledge of the common pitfalls of human thinking and how to avoid them. (Logic, as the name of my blog implies, is a theme I will return to frequently.)

The problem of data mining is both common and often subtle and missed. It is rooted in both the nature of human brain function and a common logical fallacy. The former is that of pattern recognition and the latter the fallacy of confusing correlation with causation.
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Feb 23 2007

Chimps with Spears

Published by under General Science

There is something endlessly fascinating about chimpanzees – all primates, really, but chimps especially. The most often cited reason is the fact that they are so eerily similar to humans, and I think this obvious speculation is probably correct. Humans have a well-documented obsession with humans, and chimps are almost human.

Historically we have tried to erect barriers between our lofty selves and mere animals, but they have been systematically smashed by scientific investigation – mostly of our closest cousins, the chimps. Chimpanzees can recognize themselves in mirrors, they can anticipate and plan for the future, they can mourn the death of loved-ones, and they can use tools. It has previously been observed that they can fashion sticks for later use as tools, for fishing termites out of mounds, for example.
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Feb 22 2007

Science and Supernaturalism

Published by under Logic/Philosophy

In response to yesterday’s post essentially on the methodological naturalism underpinning science, A. N. Mouse wrote: “Supernaturalism may not be falsifiable, but non-supernaturalism is. All the supernaturalists have to show is one bona fide verifiable miracle (like levitating Richard Dawkins on stage, surrounded by a choir of angels and flying pigs) and the entire materialistic underpinning of science will be blown out of the water.”

This is actually a good segue into part two of this discussion – can materialism/naturalism be falsified? I argue that it cannot be. Arthur C. Clarke wrote, “Any sufficiently advanced technology is indistinguishable from magic.” This is the essence of why it is not possible to falsify naturalism. If, as Mouse suggest, Dawkins were levitated on stage, how could we know that the feat was not accomplished using advanced technology. The question also reminds me of a quote from Dr. McCoy on the classic Star Trek series, who once joked, “Once, just once, I’d like to be able to land someplace and say ‘Behold, I am the Archangel Gabriel.’”
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Feb 21 2007

Buckley on Darwin

Published by under Creationism/ID

For science to function optimally it must be free from ideology. Ideology constrains our thinking. It forces us to cogitate backwards – to start with an ideologically desired conclusion and then cherry pick evidence, contort logic, and choose emphasis that appears to support that conclusion. This pathological process is the essence of pseudoscience, and of course my perpetually favorite example of this is creationism.

William F. Buckley Jr., a conservative columnist and thinker, has aligned himself (as has, unfortunately, a significant portion of the political right) with creationist ideology. Now we expect from political commentators, especially those who have staked out an ideological turf, like conservatism in the case of Buckley, that they will marshal what arguments they can to defend their turf. We don’t expect objectivity, we expect advocacy. It’s bad enough when ideological advocacy becomes excessively rigid in the world of politics, but when such intellectual habits and methods are applied to essentially scientific questions, we have a real problem.

Buckley, an undeniably articulate, educated, and thoughtful intellect, flounders when he attempts to defend creationist ideology on the scientific question of evolution – as he did in a recent editorial.
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Feb 20 2007

Eyes and Personality

Several readers have sent me this article on the discovery of a link between personality and the iris of the eye. The study raises several interesting concepts in biology.

The study basically shows a link between certain specific characteristics visible in the iris (the colored part of the eye) and personality. To quote the article:

“The researchers looked at crypts (pits) and contraction furrows (lines curving around the outer edge of the iris), which are formed when pupils dilate.
It was found that those with more crypts were likely to be tender, warm and trusting, while those with more furrows were more likely to be neurotic, impulsive and give in to cravings.”

The study is accepted for publication but not yet in print. To put the study in context in terms of its utility as scientific evidence, the study has found a correlation between two biological factors. Such evidence does not demonstrate cause and effect. Also, since correlations can be found randomly they are often not considered confirmed until they are replicated by later studies. Also, to be useful scientifically they must lead to a causal hypothesis that leads to predictions that can be tested. In other words – what does the correlation mean and how can we test it?
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Feb 15 2007

A Visit to Kennedy Space Center

Published by under General Science

On my weekly podcast we have discussed several times the question of how much emphasis NASA specifically, and human exploration of space in general, should place on manned space flight vs robotic exploration. Bob Park makes an excellent practical argument for putting our resources into robotic exploration – it is more safe and cost effective, and future generations will be increasingly comfortable with a “virtual” presence in space.

Phil Plait, James Randi, and others (myself included) have taken the position that while all of Park’s claims are true, putting people in space has a romantic appeal that robots and probes simply cannot capture. Since space exploration requires publics support, and public support is driven largely by the vision of people in space, this will always be an important component of any space program. Also, it just seems like it is our destiny as a race to move off of our home planet and out into the universe. Stephen Hawking has recently argued that it is in fact necessary for our survival as a race.
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Feb 14 2007

Suffer the Little Children

Isabelle Prichard is a 13 year old girl, and recently her doctors found a mass in her brain that they believe is cancer. They recommend immediate surgical removal. Her parents, however, do not believe their daughter’s doctors. Rather they have placed their trust in Russian self-proclaimed psychic healer Nicholai Levashov who believes the mass represents new brain tissue growth. So the mass will remain untreated.

This story raises many issues, and strong emotions on all sides. But first let me give the back story that led Isabelle ‘s parents to their extraordinary conclusion. Isabelle (according to press reports) was born with a severe form of brain cancer called glioblastoma multiforme (GBM). She had four surgeries to remove the tumor; the first three times it grew back, the fourth time she had a sustained remission (until now, apparently). This outcome is on the good end of the spectrum for GBM but not unheard of.
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Feb 12 2007

I Think therefore I See

I’m vacationing in Florida, which happens to be a great place for birding, so I took my daughter to a local nature preserve this morning. I took up birding as a hobby only recently and it provided for me a concrete example of how our mental model of the universe shapes what we see. For 38 years I saw the world through the eyes of a non-birder, and in the last four years my eyes have been opened to a far more detailed and complex avian landscape (skyscape?).

I have always enjoyed nature, so I was familiar with the birds common to Connecticut where I live. I could recognize crows, doves, blue jays and cardinals. I noticed hawks in the sky, and awaited the robins of spring. There were little black birds and little brown birds and then the more exotic birds I would see in pet stores and on TV. It was a very small feathered universe.

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