Weekend Post - You can't trust your eyes. Or your brain.

You can’t trust your eyes. In fact you can’t trust any of your senses. Or even your brain.

One of the most interesting areas of scientific investigation is the study of perception. I remember that as a teenager I became moderately obsessed by visual illusions and wondering how my brain could so easily be fooled.

The image here is a good example. Which of the two horizontal lines is longest? The surprising answer, even when you know it’s true, is that both horizontal lines are exactly the same length. But that’s not what your brain tells you. Your brain demonstrates quite how easily it can be fooled when it fails to correctly interpret this sort of illusion.

There are hundreds of similar examples of such illusions, some much more complicated than this one. They all exploit the sort of perceptual mechanisms that evolved over millions of years that might have been useful in the jungle or savannah where our species originated but aren’t useful any longer in the world of newspapers, smartphones and the Internet.

The great realization is that illusions like the “Müller-Lyer illusion” shown above are just the tip of the iceberg. It’s not just our vision that can be deceived, it’s our entire brain. That’s when an illusion transforms itself into that much more dangerous animal, a delusion.

One of the most common delusions we can all easily experience is called “confirmation bias”. The Skeptic’s Dictionary describes this as “a type of selective thinking whereby one tends to notice and to look for what confirms one's beliefs, and to ignore, not look for, or undervalue the relevance of what contradicts one's beliefs.” More simply, it’s the mistake of noticing and remembering things that confirm our prejudices and ignoring, or simply not seeing the things that contradict them.

I had a conversation with someone not too long ago who suggested that religious believers are more charitable than non-believers. He seemed genuinely surprised when I pointed out that perhaps the two most charitable people in the world, Bill Gates and Warren Buffett both describe themselves as agnostics. He admitted that he knew this but had “conveniently” forgotten it. I think it’s plausible that this was because these facts didn’t fit in with his worldview. Similarly, it’s easy enough for those of us who describe ourselves as atheists to forget that the vast majority of Catholic priests, for instance, are decent people and not child abusers. We remember what we find convenient to remember, not what’s inconvenient. That’s a delusion.

Another example is homeopathy. Every piece of scientific research into homeopathy has confirmed what common sense suggests. It’s nonsense and has no effect. However there are vast numbers of people who swear by it based on anecdotes like “I had a cold, took a homeopathic remedy and within about a week I was better!”

Of course they were better. That’s how colds work, they go away after about a week or 10 days all by themselves whether you take a bogus remedy or not. People forget that but remember the time that they took the useless homeopathic remedy. Believers in so-called complimentary therapies remember the times that the delusional beliefs were falsely “confirmed”.

We also make the common mistake of assuming that correlation implies causation. Because two things happen at the same time or in parallel we assume that they must be connected and one must cause the other. A good example is the observation that increases in medical knowledge in the last century have coincided with a dramatic increase in the number of deaths from cancer. Does this mean that better medicine causes cancer? Of course not, all that’s happening is that the greater lifespan brought about by better medicine has caused people to live longer and older people are much more likely to die of cancer. Cancer is an old person’s disease. Now that we’re much less likely to die from smallpox, typhoid or violence we’re dying of different things instead.

In the same way, the assumption that more and more older people are dying of cancer is somehow caused by the new presence of cellphone masts is another delusion. There is no evidence that cellphone “radiation” causes cancer. In fact the evidence suggests that it doesn’t but it’s extremely human to notice that your aged relative died shortly after the local mast was erected and that one must have caused the other. Tragically your aged relative was going to die anyway.

The good news is that simply knowing about human psychology goes a long way towards combatting these delusions. The better we understand how our brains work (and sometimes fail) the better we can avoid dangerous delusions.

Weekend Post - Radiation

“Radiation”

It’s a horrible word, isn’t it? It conjures up images of the burnt victims of Hiroshima, their skin peeling, waiting for radiation sickness to kill them. More recently the nuclear disasters at Chernobyl and Fukushima in Japan brought back those images. But how dangerous were these disasters? How many people actually died as a result of both these accidents?

This is where things get difficult. It’s impossible to say with certainty with any cancer victim that a particular thing caused their cancer. However you can look at the number of deaths that’s more than might be expected. In the initial explosion at Chernobyl 25 years ago, 57 people were killed but subsequently the only noticeable effect has been a dramatic increase in the numbers of children with thyroid cancer. The good news is that thyroid cancer is easily and successfully treatable and so far only 15 people have died from thyroid cancer in the area. While that’s 15 tragic deaths too many it’s not much more than would be expected anyway. Similarly there appears to have been no increase in birth defects or other cancers. Nobody is going to say that the radiation leak was a good thing but the effect is much, much lower than everyone feared.

Regarding Fukushima it’s really too early to say but the initial number of deaths was minimal and those few deaths were nothing to do with radiation. It’s impossible to predict future deaths but the news is not nearly as bad as was suggested by the press at the time.

On the subject of the danger of nuclear power production you also have to consider the dangers of other ways of producing power. According to the American Cancer Society between 50,000 and 100,000 Americans might die each year from the pollution caused by conventional, mainly coal-based, power stations. That’s a risk we should all be worrying about.

But what about other types of radiation? Are they dangerous? Well, that depends. “Radiation” covers a number of things. Ask a scientist and you’ll discover that radiation is divided into two main categories: ionizing and non-ionizing. Ionizing radiation has enough energy to ionize, or break down atoms. It’s ionizing radiation that causes radiation burns by breaking down the atoms in skin cells. Ionizing radiation can also break down the atoms in DNA that might result in cancer. It’s this type of radiation that is often released by radioactive sources like those found in nuclear power stations. However, as we’ve found from the experience at Chernobyl the risk isn’t nearly as high as we all fear.

The other type of radiation, the non-ionizing type, typically has much less energy, not enough to actually damage any atoms it might meet. That doesn’t mean that it can’t cause damage but the types you and I are likely to encounter are almost all perfectly safe because the energy levels and frequencies are so incredibly low.

The best example of non-ionizing radiation is the one we see every day, just by opening our eyes. Visible light is all around us all the time, even at night, it’s what we use to see things. Visible light is not ionizing. It doesn’t have enough energy to break atoms. A common misunderstanding is about sunburn which people often believe is caused by the light of the sun. In fact it’s the ultra-violet light from the sun that is ionizing, that causes the burns.

What about the most controversial of all the non-ionizing radiations: the radio waves that are used to transmit cellphone calls? Let’s start with a simple fact. The radio waves used by cellphones and cellphone masts use a frequency that is 10 million times lower than the level required to ionize. Unless radiation can ionize atoms it simply can’t cause cancer. This isn’t an assumption, it’s just physics. The radio waves used by your cellphone are as safe as the radio waves used by your chosen radio station.

But what about that World Health Organization report that was published earlier this year that everyone read, the one that said there WAS a risk from cellphones and that they might cause cancer? Unfortunately their report was selectively quoted. They reported just one study that suggested such a link but the papers neglected to report the vast number of other studies that showed there was no relationship between cellphone use and cancers of the brain or central nervous system. Perhaps the most telling fact is that the global levels of such cancers hasn’t changed a bit since the world started using cellphones. In fact the only widely accepted risk from cellphone use is falling in a fountain while texting. Do a search on YouTube for “fountain texting” and see if you can stop laughing.

The lesson is not to believe what you read in newspapers. Do some research, be skeptical and just because someone says it, that doesn’t mean it’s true. And yes, that DOES go for me as well.

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Sources:

My initial source for this was an excellent episode entitled of the Skeptoid podcast by Brian Dunning called "Rethinking Nuclear Power" [transcript here]. It was there that I found the report from the American Cancer Society which suggests the number of deaths from fossil-fuel energy production.

For a general overview of radiation see the Wikipedia page on radiation, in particular the distinction between ionizing and non-ionizing radiation.

The WHO report on cell phone radiation effects is here and includes the following paragraph:

"A large number of studies have been performed over the last two decades to assess whether mobile phones pose a potential health risk. To date, no adverse health effects have been established as being caused by mobile phone use."

There's also a good summary of the facts on the Cancer Research UK site here. Read carefully the section on Category 2B risks (which currently includes cellphones). They describe this group as:

"a bit of a catch-all category, and includes everything from carpentry to chloroform."

For a good overview see the always useful Skeptics Dictionary. In particular see the page on electro-magnetic fields and radiation here and comments on the WHO story here.

Regarding the coverage of the cell phone mast in Mochudi that was destroyed by an outbreak of mass hysteria see the Mmegi story here. See also the appearance of the charlatan called Barrie Trower here. Barrie Trower is not all that he seems.

To see what can happen when you text while walking click here but remember that if you laugh at someone else's misfortune you're a bad person.

Corrections:

In the printed version of this article I referred to the American Cancer "Association", not Society.